V-f- £9 c», 3 ILLINOIS STATE LIBRARY SPRINGFIELD EDWARD J. HUGHES Secretary of State and State Librarian r*-t Date Due MAR 1 3 /< 4f} JAi\j 2 - 4S , Lrr . rj 7 »A JE.C 4 1 y JBN 1 4 "W APR 3 0 74 H 7as. fni e f Library Bureau Cat. no. 1137 Digitized by the Internet Archive in 2018 with funding from University of Illinois Urbana-Champaign https://archive.org/details/floodcontrolrepoOOilli gf?98%~?'5 STATE OF ILLINOIS LOUIS L. EMMERSON, Governor Department of Purchases and Construction HENRY H. KOHN, Director FLOOD CONTROL REPORT An Engineering Study of the FLOOD SITUATION IN THE STATE OF ILLINOIS Prepared under Direction of THE DIVISION OF WATERWAYS WM. F. MULVIHILL Supervisor Illinois Waterway Construction L. D. CORNISH Chief Engineer JACOB A. HARMAN, L. T. BERTHE, MURRAY BLANCHARD. L. C. CRAIG, Consulting Engineers CHICAGO 220 S. State Street June, 1929 fPrinted by authority of the State of Illinois.] Journal Printing Company, Springfield, Illinois. 19 3 0 LETTER OF TRANSMITTAL. June, 1929. To His Excellency, the Governor, the Director of Purchases and Con¬ struction and the Members of the General Assembly of the State of Illinois. FLOOD CONTROL REPORT. Gentlemen : The State of Illinois is bounded and bisected by mighty rivers, all of which are subject to periodical overflow, and are tributaries of the Mississippi. Flood damages in our State during the past six years have amounted to more than $30,000,000. The city of Beardstown was in¬ undated and Cairo was saved only by the heroism of her citizens and the fact that a crevasse in the levee below the city lowered the Cairo water level at flood crest. The flood of 1926 was in the Fall of the year and destroyed much of the standing crop in the districts submerged. The 1927 flood came in the Spring and prevented any crop that year. The effect was sub¬ stantially that of one continuous flood covering a period of seven or eight months and created a situation which prompted the Fifty-fifth General Assembly to pass an Emergency Flood Relief Act, approved July 7, 1927, with an appropriation of $1,500,000 to furnish emergency relief in submerged areas and for the repair and reinforcement of levees which had been, or were in danger of being, destroyed by flood waters. Another appropriation of $350,000 was made for the protection of the city of Beardstown against flood waters of the Illinois River. At my suggestion the Fifty-fifth General Assembly also included in the Departmental Appropriation Bill the sum of $50,000 “for an en¬ gineering study of the flood situation throughout this State, and for use in conjunction with other states and the Federal government in the development of comprehensive plans for flood prevention and the per¬ manent relief and protection of the people of Illinois from the menace of future devastation by flood waters.” The report submitted herewith has been prepared under the super¬ vision of the writer and Mr. Lorenzo D. Cornish, Chief Engineer of the Division of Waterways. It is divided into two parts, Part I, relating to Flood Control of the Illinois River, which lies wholly within this State, and Part II, deal¬ ing with the Ohio and Mississippi Rivers as flood conditions therein affect the State of Illinois. Respectfully submitted, Wm. F. Mulvihill, Supervisor Illinois Waterway Construction. . ! ' ■ V * TABLE OF CONTENTS Letter of Transmittal by Wm. F. Mulvihill, Supervisor Illinois Waterway Construction. Introduction by Chief Engineer, Division of Waterways. PART I—FLOOD CONTROL—ILLINOIS RIVER. Page. Letter of Transmittal to the Chief Engineer of the Division of Waterways by Jacob A. Harman_19 Findings and Recommendations__ 20 SECTION I—GENERAL DISCUSSION. Introductory_23 Floods of the Illinois River_____23 Watershed Maps_ 24 Historical sketch of Illinois River__25 Description of Illinois Watershed_ 27 The River Bottoms_ 28 Geology_ 29 Waterway Improvement in the Illinois Valley_____32 Sources of Information_ 33 Rivers and Lakes Commission Report 1915_ 34 Levee Districts in the Illinois Valley......35 Aerial Photographs of the 1926 Flood of the Illinois River__46 Profile of Principal Floods_______52 Straightening Tributaries_ 52 Flood Crest Travel_ 52 Levee Districts Flooded_ 52 Diversion of Water from Lake Michigan__52 Effect of Levees on Flood Stages_57 Litigation_ 58 Investment Values_ 58 Rainfall and River Stages_____59 Storm Centers and Rainfall_ 60 Rainfall Maps__ 62 Rainfall Frequency as Related to Floods on Illinois River...62 SECTION II—HYDRAULICS. Introductory__ 63 U. S. Engineers Surveys of 1902-1905___63 Valley Sections and Storage Areas..______ 63 Stage Records_ 65 Discharge_ 73 Present Condition as Leveed________73 List of Discharge Measurements_____74 Current Meter Discharge Measurement Conditions______75 Stage-Discharge Relation...........75 Rating Curves. 76 Stage-Slope-Discharge Relation__ 76 Method of Constructing a Rating Curve_________77 Comparison of Observed and Diagram Discharges_______79 Diagram and Rating Curve Discharges Compared____79 Rating Diagrams.. 79 Discussion of Discharges_ 79 Maximum Stage__________80 6 FLOOD CONTROL REPORT. SECTION III—FLOODS. Page . Discussion of Floods of 1904, 1913, 1922, 1926, 1927_ 80 Distinction between Crest Profile and Profile of Date_ 83 Levee Breaks—1926_________84 Storage and Levee Districts........84 SECTION IV—BACKWATER PROFILE COMPUTATIONS AND COEFFICIENT OF ROUGHNESS “n”. Flow Formulas_ 86 Applications of Flow Formulas_87 Determination of Coefficients_______ 87 Coefficient “n” for Channel-Selected Reaches___ 87 Conclusion on Value of “n” for Manning Formula for Illinois River_97 Comparison of Value of “n” for Manning Formula and Kutter Formula.. 97 Flood Crest Discharge Profiles and Backwater Profiles_____98 Comparison of Discharges Rating Curves and Diagrams—Peoria, Havana, Beardstown, Pearl..104 Maximum Flood Discharges___________105 Flood Flow over Valley Land____107 Cleared Floodways_ 107 Silt Accumulation in the Floodway_______..108 Damages to Flooded Districts_____108 Flood Control Methods_______109 Discharge and Storage Relations____110 Flood Heights Reduced by Set-Back Levees____...Ill Levee Enlargement and Levee Set-Backs___115 Levee Enlargement Specifications.._ 122 Chautauqua District Left Open__ 123 Cities along the Illinois River____-.-123 Valley Districts near Beardstown_124 TABLES. 1. Drainage District Statistical Data, Illinois River Valley..— 38 2. Drainage District Statistical Data, Illinois River Valley_ 40 3. Drainage District Statistical Data, Illinois River Valley_ 42 4. Drainage District Statistical Data, Illinois River Valley- 44 5. Levee Breaks 1922 and 1926_ 53 6. Sanitary District of Chicago Main Channel Mean Monthly and Yearly Discharge.. 57 7. Flood Plane Areas and Increase in Flood Storage 1904-1926_58 8. Summation Statistical-Data Levee Districts Illinois River Valley___59 9. Rises in Feet Produced by one inch of Rainfall__---60 10. Normal Monthly Rainfall, Illinois River Watershed- 61 11. Rainfall at Peoria Flood Period, 1926-1927______- 61 12. Stations and Elevations of Gages, Illinois River-- 65 13. Annual High Water Data and Elevations of Illinois River-- 66 14. Comparison of Simultaneous Discharge Measurements--75 15. Comparison of Simultaneous Discharge Measurements Different Years-75 16. Typical Computation for Grouping Discharge Measurements-- 78 17. Balance Sheet of Flow.,_ 81 18. Storage in Levee Districts 1926- 85 19. Levee Districts Illinois River Valley—Showing Area in Acres of Flood Plane of 1926—Capacity below that Plane in Acre-Feet---85 20. Computed Values of “n” Manning Formula for selected Reaches of Restricted Overflow Illinois River-------88 21. Illinois River Flood Crests 1926—Discharge Rates for Principal Gaging Stations and Reaches from Peoria-Grafton----- 91 22. Computed Profile Flood Crests April, 1926, Peoria-Grafton- 92 23. Illinois River Flood Crest, 1927—Discharge Rates for Principal Gaging Stations and Reaches, LaSalle to Peoria..___-......94 24. Computed Profile Flood Crest April, 1927, LaSalle to Peoria-95 25. Typical Values of Coefficient “n” for Manning Formula and Kutter Formula for Crest Dis¬ charges of Illinois River April, 1926, all Levees Holding.....96 TABLE OF CONTENTS. IV l TABLES—Concluded. Page. 26. Comparison of Observed and Computed Flood Crests April, 1920, April, 1922 and April, 1927_100 27. Backwater Elevations of Illinois River for Crest of Flood Stages Mississippi at Grafton cresting simultaneously with Normal Illinois River Flood Crest____..101 28. Flood Stages with and without Levees Set-back____113 29. Levee Enlargements and Set-backs, cubic yards of Fill Required.. ..116 30. Levee Enlargements and Set-backs, cubic yards of Fill Required_ 118 31. Levee Enlargements and Set-backs, cubic yards of Fill Required_ 119 32. Levee Enlargements and Set-backs, cubic yards of Fill Required_ ..120 33. Resume of Levee Enlargement and, Set-back, Grafton-Peoria____.121 34. Estimated cost for the Enlargement of Levees at the Present Locations and for the Enlarge¬ ment of Levees used with Set-back Levees.......122 FIGURES. Fig. No. Page. 1. Map of Illinois Showing the Watershed of the Illinois River......125 2. Map of Illinois River Watershed_______126 3. Profile of Low Waters and Flood Crests of the Illinois River_____126 4. Map of Illinois River Flood Plane Showing Drainage and Levee Districts Constructed prior to 1904___^___126 5. Map of Illinois River Flood Plane Showing Drainage and Levee Districts Constructed prior to 1913________126 6. Map of Illinois River Flood Plane Showing Drainage and Levee Districts Constructed prior to 1926_______________126 7. Illinois River Watershed-Rainfall Map, Storm of March 11 to April 22, 1927... 127 8. Illinois River Watershed-Rainfall Map, Storm of September 1 to October 5, 1926_ 128 9. Illinois River Watershed-Rainfall Map, Storm of March 10 to April 18, 1922___129 10. Illinois River Watershed-Rainfall Map, Storm of January 1 to January 31, 1916_130 11. Illinois River Watershed-Rainfall Map, Storm of March 12 to March 28, 1913_131 12. Illinois River Watershed-Rainfall Map, Storm of February 25 to April 1, 1904_132 13. Illinois River Watershed-Rainfall Map, Storm of February 21 to March 7, 1900. 133 14. Illinois River Watershed-Rainfall Map, Storm of March 9 to 29, 1898_ 134 15. Illinois River Watershed-Rainfall Map, Storm of January 1 to March 11, 1893_135 16. Illinois River Watershed-Rainfall Map, Storm of April 27 to May 16, 1892_ 136 17. Typical Cross-Section of Illinois River_ 137 18. Storage Diagram, LaSalle to Otter Creek...........138 19. State Hydrographs—Flood of 1926 from Morning Gage Readings___139 20. Stage Hydrographs—Flood of 1927 from Morning Gage Readings.._ .140 21. Stage Hydrographs—Flood of 1926 from all A. M. and P. M. Gage Readings..__141 22. Stage Hydrographs—Flood of 1926 from all A. M. and P. M. Gage Readings_142 23. Comparison of Rating Curves at Peoria as Derived from Measurements made 1900-1904_143 24. Discharge Curves by U. S. Engineers, War Department_ 144 25. Sangamon River Rating Curves—Discharge at Oakford.. ..145 26. Rating Curve of Sangamon River at Chandlerville from Oakford Discharge Measurements_146 27. Discharge Curves by U. S. Geological Survey......147 28. Rating Curves—Discharges at Beardstown, U. S. Geological Survey, U. S. Engineers and Sani¬ tary District of Chicago_____148 29. Discharge Graphs—Flood of 1926________149 30. Discharge Graphs—Flood of 1927_ 150 31. Typical Rating Diagram....151 32. Illinois River Stages, Peoria to Pearl, Referred to Peoria-Pearl Stage, Oct. 5, 1926_152 33. Study of October Flood, 1926, Beardstown to LaGrange.....153 34. Manning’s Formula Diagram______154 35. Typical Discharge Diagrams______155 36. Profile of Observed and Computed Stages—Flood Crests April, 1920, April, 1926, April, 1927_156 37. Backwater Flood Crest Discharge Profiles Illinois River, Grafton to LaSalle_156 38. Comparative Discharges—Rating Curves and Diagrams, Peoria and Havana....157 39. Comparative Discharges—Rating Curves and Diagrams, Beardstown and Pearl...158 40. Illinois River from Beardstown to Montezuma—Suggested Levee Set-backs for Reducing Flood Heights_______159 41. High Water Profiles for Levee Set-backs._______159 42. Profiles of High and Low Waters and Levees, Illinois River.....159 8 FLOOD CONTROL REPORT. AERIAL PHOTOGRAPHS—OCTOBER 14, 1926. Picture No. Page. 1. Looking up the Illinois River just above Pekin..._..46 2. Looking northwest about 4 miles above Havana__ 47 3. Looking northeast of Beardstown_ 48 4. Looking upstream above Beardstown—showing River Channel_ 49 5. Looking upstream with LaGrange Lock at left center__ 50 6. Looking upstream showing Meredosia at the right_ 51 PART II—FLOOD CONTROL—MISSISSIPPI AND OHIO RIVERS. SECTION I—DISCUSSION BY DIVISION OF WATERWAYS. Page. Description___________161 Flood Control along the Mississippi River__ 161 Flood Control along the Ohio River. 162 Floods of the Mississippi and Ohio Rivers_______162 The Flood of 1927__________163 The Flood of 1929_____•____163 Protection from Future Floods of the Mississippi and Ohio Rivers__ 164 Flood Protection of the City of Cairo and Vicinity... 165 History of the City of Cairo________165 Barge Line Terminal___...I......165 Railroad and Industrial Center_________166 History of Levee Building at Cairo.........166 Cost of Levees___________167 Necessity of Additional Protection.......167 Sand Boils and Seepage------168 Slides_____171 Caving Banks_____________172 The Cairo Drainage District_________172 Mounds and Mound City...—...173 The Army Flood Control Plan as Affecting Cairo______173 Flood Control Board's View............174 Protection of Cairo a Vital Matter........175 SECTION II—REPORT OF THE BERTHE ENGINEERING CO. The Problem at Cairo--------175 Flood Menace at Cairo..............175 Measure of Protection Necessary--------175 Demand for Further Study.....—----176 Location and Economic Importance.......176 City of Cairo Valuations.........176 Protective Works and Topography__—---176 Height of Cairo Levees and Comparative Differentials.........—.177 Sand Boils----177 C. E. Smith Report______178 Drainage and Industrial District--------178 Length and Grades of Cairo Levee Systems........178 River Stages and Flood Volumes at Cairo—1882 to 1927 inclusive.....179 Size of Flood to Protect Against............180 Maximum Probable Flood as determined by Mississippi River Commission....180 Maximum Possible Flood as Determined by Weather Bureau......180 Relative Importance of Protection____—......181 Emergency Protection Required at Cairo.....—.....181 Reduction of Differentials by Filling Method, 100% Effective in Every Flood—..182 Hazards Emphasized in C. E. Smith Report------182 Recommendations of C. E. Smith Report Concurred in......183 Filling of Low Areas.......-.183 Summary for City—Filling Required.......---183 Cairo Drainage District—Filling Required.........184 TABLE OF CONTENTS. 9 SECTION II—REPORT OF THE BERTHE ENGINEERING CO—Concluded. Page. Army Plan Fails to Protect Against Greatest Hazard at Cairo____184 Reduction of Flood Levels-----185 Effect of Windstorms on Free-Board Required on Earthen Levees_185 Minimum Reduction in Flood Plane required to make Cairo Levee Grades Adequate...185 Permanent Protection_______186 Can Levee Grades be Raised at Cairo_________186 Not Prohibitive in Cost_________186 Three Foot Raise in Levee Grade Practicable.......187 Economical and Advantageous to Cairo......187 Authority of Governmental Agencies to Reduce Differential by Filling___187 Will Reduce Pumping Costs at Cairo---187 Additional Drainage Requirements_____188 Ohio Water Front Treatment_____188 Problems at Mounds and Mound City, 1927 Flood and Present Conditions....189 Flexibility of Plan_____189 Non-Interference with Highway Surfacing and R. R. Tracks______189 Cache Flood way Preserved........._..190 Protective Works within Scope of Main River Improvements___190 Present Protective Works at Mound City........190 Encroachment of Manufacturing Plants upon Levee__.___190 Riverside Enlargement Possible North from Railroad Avenue____191 Landside Enlargement necessary South of Railroad Avenue___191 River Bank Scour.........191 Probable Cost_____192 Levee Mileage in this Protective Unit________192 Advisable Additional Levee___,__193 Mississippi River Levees West of Cache River____193 Within Jurisdiction of Mississippi River Flood Control Plan.........194 Conclusions and Recommendations____194 SECTION III—COMMENTS AND CONCLUSIONS OF THE DIVISION OF WATERWAYS. The Greatest Possible Flood_____195 Frequency of the Greatest Possible Flood________196 City vs. Country Areas—Flood Protection_____196 Protection from the Greatest Possible Flood a Necessity of the Present..__197 The Bird’s Point—New Madrid Floodway_____197 Freeboard Necessary in Earth Levee Construction.......197 Necessity of Protecting Areas North of the Cairo Drainage District____198 Filling of Low Areas of Cairo and Cairo Drainage District.._____198 Raising and Strengthening Levees....199 The Concrete Sea Wall______201 Flood Protection Provided by the Flood Control Act of 1928___201 Estimate of Cost of Recommended Additional Flood Protection_201 Conclusions—Recommended Additional Flood Protection for Cairo, Mound City and Mounds_202 SECTION IV—THE MISSISSIPPI RIVER FLOOD CONTROL ACT. Text of Mississippi River Flood Control Act._______202 FIGURES. Fig. No. Page. 43. Map of Mississippi River Flood Plain between Cairo and Rock Island—Showing Drainage and Levee Districts__ 208 44. Profile of Low Water and Flood Crests between the Ohio River and the Wisconsin State Line_208 45. Map of Cairo. Illinois and Vicinity..........208 46. Map of Cairo, Illinois, Showing Area Proposed to be Filled____.208 47. Map Showing Location Flood Control Works, Mounds, Mound City, Cairo and Adjacent Terri¬ tory.... ..208 48. Map Indicating Possible Alternative Location Mississippi River Levee above Cache River Levce208 10 FLOOD CONTROL REPORT. ILLUSTRATIONS. Picture No. Page. 7. South Quincy Drainage and Levee District near Quincy, III., Break in Levee April 24, 1929.163 8. South Quincy Drainage and Levee District. View of Break about 24 hours after Preceding Picture was Taken_ 164 9. Degognia Drainage and Levee District High Water of 1927. Sand Bagging Levee During a Storm_ 165 10. Cairo Drainage District, Mississippi River Levee During High Water of 1927. Inner Slope of Levee Sand Bagged to Prevent Slides___169 11. Cairo Drainage District, Ohio River Levee During High Water of 1927. Sand Boil Area “welled up” with Sand Bags. 170 12. Cairo, Illinois, High Water of 1927. A Typical Sand Boil__171 13. Cairo, Illinois, Seawall Built by the State of Illinois in 1915..200 TABLE OF CONTENTS. 11 APPENDIX “A.” RAINFALL STUDIES. Page. Introduction________..____211 Analysis of 1926-1927 Flood Period_____212 Analysis of the Flood of April, 1922_215 Analysis of the Flood of January, 1916_ 217 Analysis of the Flood of March and April, 1913_ 218 Analysis of the Flood of March and April, 1904_ 220 Analysis of the Flood of March, 1900_ 222 Analysis of the Flood of March and April, 1898__..____223 Analysis of Floods of March and May, 1893---224 Analysis of Floods of May and June, 1892---.--225 Comparison of Flood Stages_226 Relation between Rainfall and Rise of River_____227 TABLES. A-l. Rainfall Stations and Their Weights....229 A-2. Weighted Average 10-day Precipitation on Illinois River Watershed—Aug., 1926- June, 1927.. 234 A-3. Weighted Average 10-day Precipitation on Illinois River Watershed—Oct., 1921- April, 1922_ 234 A-4. Weighted Average 10-day Precipitation on Illinois River Watershed—Dec., 1915- Feb., 1916. 236 A-5. Weighted Average 10-day Precipitation on Illinois River Watershed—Jan., 1913- Apr., 1913_ 239 A-6. Weighted Average 10-day Precipitation on Illinois River Watershed—Jan., 1904 April, 1904_ .....242 A-7. Weighted Average 10-day Precipitation on Illinois River Watershed—Jan., 1900- May, 1900_ 245 A-8. Weighted Average 10-day Precipitation on Illinois River Watershed—Jan., 1898- June, 1898_ 248 A-9. Weighted Average 10-day Precipitation on Illinois River Watershed—Jan., 1893- July, 1893_ 251 A-10. Weighted Average 10-day Precipitation on Illinois River Watershed—Mar., 1892- Aug., 1892_254 A-ll. Total Normal and Monthly Precipitation Northern District, Central District, and Combined Northern and Central Districts_257 A-12. Rainfall and River State Relation by Individual Storm Periods—1926-1927..261 A-13. Rainfall and River Stage Relation by Individual Storm Periods—1921-1922_263 A-14. Rainfall and River State Relation by Individual Storm Periods—1915-1916... 264 A-15. Rainfall and River Stage Relation by Individual Storm Periods—1913_ 265 A-16. Rainfall and River State Relation by Individual Storm Periods—1904_ 266 A-17. Rainfall and River Stage Relation by Individual Storm Periods—1900. ..267 A-18. Rainfall and River Stage Relation by Individual Storm Periods—1898_ 268 A-19. Rainfall and River Stage Relation by Individual Storm Periods—1893_269 A-20. Rainfall and River Stage Relation by Individual Storm Periods—1892. 270 A-21. Maximum Stages Reached in 10 Flood Periods. (In Text)_227 A-22. Rises in Feet Produced by one inch of Rainfall. (In Text)_228 PLATES. A-l, A-2. Rainfall and River Stages, 1892_272 A-3. Rainfall and River Stages, 1893_ ..274 A-4, A-5, A-6. Rainfall and River Stages, 1898_ 275 A-7, A-9. Rainfall and River Stages, 1900- 278 A-10, A-12. Rainfall and River Stages, 1904.._ 281 A-13, A-15. Rainfall and River Stages, 1913. 284 A-16, A-21. Rainfall and River Stages, 1915-1916- 287 A-22, A-28. Rainfall and River Stages, 1921-1922. 293 A-29, A-36. Rainfall and River Stages, 1926-1927. 300 12 FLOOD CONTROL REPORT. APPENDIX “B.” B-l. B-2. B-3. B-4. B-5. B-6. B-7. B-8. B-9. B-10. B-ll. B-12. B-13. TABLES. Page. Names of Reaches for Storage and Back Water Computations_308 Illinois River Cross Section Data___309 Storage above Bank Full Stage.....'_325 Discharge Measurements of Illinois River at Divine, Morris, Ottawa, LaSalle, Depue, Chillicothe, Peoria, Havana, Beardstown, Pearl, Hardin and Reich’s Ferry330 Flow Conditions during Discharge Measurements, Sanitary District of Chicago_342 Rating Diagram Discharge at Peoria._ 343 Rating Diagram Discharge at Havana__ 346 Rating Diagram Discharge at Beardstown_ ..347 Rating Diagram Discharge at Pearl_ 349 Rating Diagram Discharge at Hardin..... 350 Illinois River Discharge from Diagram, U. S. Engineers, U. S. Geological Survey— Peoria_ 352 Illinois River Discharge from Diagram, U. S. Engineers, U. S. Geological Survey— Havana__ 353 Illinois River Discharge from Diagram, U. S. Engineers, U. S. Geological Survey —Beardstown... 354 PLATES. B-l, B-10. Storage Diagrams by Reaches_ B-ll, B-48. Stage Hydrographs, 1890-1927 inclusive. 355 365 FLOOD CONTROL REPORT. 13 FLOOD CONTROL REPORT. An Engineering Study of the Flood Situation in the State of Illinois. INTRODUCTION By Lorenzo D. Cornish, Chief Engineer Division of Waterways. The Fifty-fifth General Assembly of the State of Illinois at its regular biennial session, as a part of House Bill No. 753, which is en¬ titled : “An Act to provide for the ordinary and contingent expenses of certain departments of the State government, until the expiration of the first quarter after the adjournment of the next regular session of the General Assembly,” appropriated the sum of $50,000.00 “for an engineering study of the flood situation throughout this State, and for use in conjunction with other states and the Federal government, in the development of comprehensive plans for flood prevention and the permanent relief and protection of the people of Illinois from the menace of future devastation by flood waters.” With this purpose in mind, as clearly expressed in the Act quoted above, the Division of Waterways has prepared this report, selecting for special study two of the flood control problems that it regards as of greatest importance to the welfare of the State,—that of the Flood Con¬ trol of the Illinois River and that of the Mississippi River as affecting the city of Cairo and vicinity. DISASTROUS FLOODS. Disastrous floods have occurred during recent years, not only in the Illinois River but in other rivers of this State. The Illinois River, on account of its relatively greater importance, has received more notice than many smaller streams which have also been flooded. Memorable floods have occurred in the Illinois River in 1844, 1904, 1913, 1922, 1926 and 1927. These floods have reached successively higher stages, not because the run-off or discharge of the river has in¬ creased since the first recorded flood of 1844, but because landowners since 1900, under provisions of State laws, have been allowed to build levees and to encroach upon the natural flood plane of the river. Drain¬ age and levee districts have been organized under the laws of the State to reclaim bottom lands. Each district that has built a levee has shut off a portion of the natural flood flow channel, thus adding to the flood heights and increasing the flood hazard of all the other districts. 14 FLOOD CONTROL REPORT. The flood of 1922 broke the levees of over half of the levee districts along the river, overflowed large areas of rich agricultural land and the cities of Beardstown, Meredosia, Valley City, Naples and Browning, caus¬ ing great damage to property and business. In 1926, and again in 1927, the disaster of 1922 was repeated, with still higher flood stages. The breaking of the levees during these floods, by providing additional flow area and storage space, decreased or checked the flood which would have reached a higher stage had the levee held and confined the waters. After the flood of 1922, Mr. M. G. Barnes, then Chief Engineer of the Division of Waterways, made a detailed study and special report on the effect of the levees on the flood stages of the Illinois River, stating very clearly that the levees must be of much greater height, or greater width of floodway provided by setting back portions of the levees, or flood-crest storage provided in some of the districts in order to avoid greater flood disasters. Along the Mississippi River, on the western boundary of the State, we have some 600,000 acres of bottom lands of which 85 per cent have been reclaimed by Drainage and Levee Districts. Floods have occurred in the Mississippi River in various years which have broken levees, flooded agricultural land and endangered the lives of city populations. During the spring of 1927 the cities of Cairo, Mounds and Mound City, in the southern part of Illinois, having a combined population of 20,000, experienced a severe Mississippi flood that for a time threatened to break all levees and drive the inhabitants from their homes. In addition to the the Illinois River there are within the State some 24 other rivers of varying degrees of importance which are subject to floods. Nearly all of these rivers have rich bottom lands, capable of growing large crops of wheat and corn and other products when fully protected from overflow. Only a portion of this area may be considered to have adequate protection at the present time. In some of these flooded areas are located cities where lack of proper sanitary conditions, during flood periods, endangers the health of the inhabitants. STUDIES AND REPORTS. From time to time the Division of Waterways, as well as its pre¬ decessor, the Rivers and Lakes Commission, has made studies and reports covering the flood control of various rivers in Illinois. The State Geological Survey of Illinois has also made several reports. These re¬ ports have included the Illinois River, Bay Creek and Cache River, the Saline, the Pecatonica, the Spoon, the Kaskaskia, the Embarrass, the Little Wabash and the Skillet Fork Rivers. A report on the Illinois River and its bottom lands, prepared by Alvord & Burdick, Consulting Engineers, under the direction of the former Rivers and Lakes Commission, was published in 1915. This report contains an analysis of the previous floods and estimates of the probable flood heights, with the levees which were then constructed and under construction completed. Also an estimate as to the probable flood height if all the land available for agricultural purposes in the lower Illinois valley should be levied and protected from overflow. The con¬ clusions and recommendations in this report were accepted by the FLOOD CONTROL REPORT. 15 Division of Waterways until the floods of 1926 and 1927 had disclosed the necessity of a new investigation to determine flood heights as affected by the more recent construction of levees. In the Third Annual Report of the Division of Waterways (1920) are published reports, covering flood control of Bay Creek, the Cache River and the Saline River, by W. G. Potter, Drainage Engineer of the Division of Waterways. The flood control of the Pecatonica River is covered by two reports, one by the Rivers and Lakes Commission in Bulletin No. 18 published in 1916, and one by W. G. Potter, Drainage Engineer, in the seventh annual report of the Division of Waterways (1924). In 1912 the Rivers and Lakes Commission published a report by Jacob A. Harman, Consulting Engineer, on the Reclamation of Lands Subject to Overflow in the Kaskaskia Valley. In 1911 the Rivers and Lakes Com¬ mission published a report made by C. G. Elliott, Chief of Drainage In¬ vestigation, H. S. Department of Agriculture, on The Prevention of Overflow of the Little Wabash and Skillet Fork Rivers. The Reclama¬ tion of Lands Subject to Overflow in the Embarrass River Valley, is covered by a report of Jacob A. Harman, Consulting Engineer, published in 1913 by the State Geological Survey of Illinois. The State Geological Survey published another report by Jacob A. Harman in 1916 on the Reclamation of Lands Subject to Overflow in the Spoon River Valley. Based on the value of protection to navigation the United States Army Engineers have made surveys of various rivers in Illinois and some of these surveys are in progress at the present time. The purpose of the reports published by various State agencies has been to provide studies and preliminary plans, which could be utilized by the local interests affected for the saving of human life and preventing the loss of crops and live stock, the damaging of roads, bridges and other structures, amounting to millions of dollars annually. On some of the rivers of the State flood control projects have been constructed in the upper portion of the valleys, only, thereby increasing the maximum flood discharge lower down. Studies should be made of these streams and surveys made from the mouth upward and a com¬ prehensive flood control plan developed for each. STATE APPROPRIATIONS FOR FLOOD RELIEF. From time to time the General Assembly of the State of Illinois has recognized the public benefit which will result from flood control and protection by appropriating State funds for this purpose. Between 1913 and 1915, $384,000 was appropriated for building flood protection works to protect the cities of Cairo, Mound City and Shawneetown on the Ohio River. In 1913, $3,000 was appropriated to rebuild the levee protecting the village of Naples and in 1925, $10,000 was appropriated to raise and strengthen this levee. The Fifty-third General Assembly of the State of Illinois, in 1923, made an appropriation for construction of levees around the city of Beardstown. The Division of Waterways prepared plans for this work, which are shown in its report for the fiscal year ended June 30, 1924. The cooperation of the city of Beardstown in this protection work was not obtained, however, until after the floods of 1926 and 1927. The Legislature of 1927 reappropriated $350,000 and, 16 FLOOD CONTROL REPORT. with funds contributed by the railroads, the protection works have now been built. The recurrence, in 1926 and 1927, of floods having greater height and greater destruction, so soon after the flood of 1922, caused the Leg¬ islature of 1927 to make an appropriation of $1,500,000. “for the purpose of furnishing all necessary and proper emergency relief in areas which have been inundated and damaged by flood waters and for making temporary repairs to, or furnishing tem¬ porary reinforcements for levees which are in danger of being damaged by the flood waters of the last several months, and to re¬ claim or restore inundated and overflowed lands.” Under this appropriation contracts were let and the levees in the Illinois Eiver valley and along the Mississippi in the southern part of this State were restored. Some of this work is still in progress. COMPREHENSIVE FLOOD CONTROL PLANS NEEDED. From the engineering standpoint, as well as from the standpoint of economy, in order wisely to spend appropriations made for flood control, comprehensive plans should be provided and a definite construction policy adopted. Heretofore studies have been made of flood control problems affecting various rivers of the State in response to local demand or as appropriations became available. Appropriations which have been made heretofore, although not a part of a general flood control scheme, as a rule, have been wisely spent and have not been wasted. But there has been no general scheme, based upon sound engineering data, providing that appropriations should go where the need was greatest and that flood control work might bear its proper relation to other construction. Interrelated with the problem of flood control we have that of pro¬ tecting navigation, and also the problems of sanitation as affecting cities and of transportation over bridges and concrete highways. The interrela¬ tion of these various problems, which affect the welfare of the whole state, requires the adoption of a State-wide, comprehensive plans for their solution. COOPERATION OF STATE AND FEDERAL AGENCIES. Section six of the Mississippi Eiver Flood Control Act, passed by Congress of the United States and approved May 15, 1928, provides that flood control works may be constructed by the Mississippi Eiver Commission on the tributaries as far as the Mississippi Eiver backwater influences their stages, provided, however, that the State or local com¬ munities must pay one-third of the cost and also furnish the right-of-way without expense. The Mississippi Eiver Commission has assumed jurisdiction over the Illinois Eiver for flood control work from the mouth to the upstream city limits of Beardstown. The back-water of the Mississippi during ex¬ treme floods influences the stage of the Illinois Eiver, however, as far as Peoria and there is a possibility that the Mississippi Eiver Commission may extend its jurisdiction to the latter city. The people of Illinois are, therefore, deeply interested in the provisions of this Act, as applied to the flood control of the Illinois Eiver and other tributaries of the Mis- FLOOD CONTROL EErORT. 17 sissippi, and the State should, it seems to me, prepare complete and com¬ prehensive plans in order that it may be in position to take advantage of any scheme of cooperation which may develop. For full text of the Mississippi Eiver Flood Control Act see Section IV, of Part II hereof. ILLINOIS RIVER FLOOD CONTROL. Illinois Eiver Flood Control has been selected for detailed inves¬ tigation and report, because this river, the largest of the State, draining some 28,000 square miles of watershed and having along its lower 226 miles over 400,000 acres of bottom land subject to overflow by floods, presents a problem the solution of which more vitally affects the welfare of the State than does that of any other river lying within its borders. The Illinois Eiver extends southwesterly across the northern and central portion of the State, a distance of 275 miles. In this distance eight railroads cross the river by means of bridges and approaches that are subject to damage during flood periods. There are also nine highway bridges, constructed or proposed, which form important links in the hard roads system of the State. Approaches to these highway bridges are in every case except one through bottom lands protected from over¬ flow by levees. There are also important secondary roads leading to ferries located behind levees. When levees break, communication is in¬ terrupted and the resulting damage to business and to private individuals can hardly be estimated. The State of Illinois is building, at a cost of $20,000,000, a water¬ way connecting the Chicago Sanitary and Ship Canal at Lockport with the Illinois Eiver at Utica. When “The Illinois Waterway” is com¬ pleted, and the Federal government has finished dredging the Illinois Eiver between Utica and Grafton, a navigable channel at least nine feet in depth will be available for barge traffic between the Great Lakes and the Mississippi Eiver. During the last eight years, under Federal gov¬ ernment supervision, there has been a great increase in barge line traffic on the Mississippi Eiver. During 1928, 546,491 tons of merchandise, grain and ore passed through the barge line terminal at Cairo alone. Similarly the completion of the Illinois Waterway will result in a rapid development of barge line traffic on the Illinois Eiver. The protection of this traffic and the preservation of all navigation during flood periods will be facilitated by the construction of proper flood control works. ' The problem of flood control along the Illinois Eiver is one requir¬ ing considerable study. For this purpose and to get out plans and recommendations with estimates of costs, the Division of Waterways employed Mr. Jacob A. Harman, Consulting Engineer, of Peoria, Illi¬ nois, who has had many years of practical experience in levee building and flood control work and a long acquaintance with the Illinois Eiver. Mr. Murray Blanchard, Hydraulic Engineer for the Division of Water¬ ways, was assigned to assist him in the study of this problem. The report of the Consulting Engineer herewith is approved as a general plan for flood control of the Illinois Eiver and the recommenda¬ tions concurred in. —2 F C 18 FLOOD CONTROL REPORT. FLOOD PROTECTION FOR CAIRO AND VICINITY. Aside from New Orleans, Cairo is the largest city of the Mississippi Valley subject to floods. The protection of Cairo and vicinity from floods of the Mississippi and Ohio Rivers is of great importance, the safety of a large population is involved and the safe-guarding of human life must be the first concern of the State. Under the provisions of the Mississippi River Flood Control Act, before referred to, the Federal government has adopted a plan for con¬ trolling Mississippi River floods. The advisability of making a study and preparing plans and estimates of cost, so as to be in a position to cooperate with the Federal government was an additional reason for in¬ cluding the study of the flood protection of Cairo in this report. Mr. L. T. Berthe of the Berthe Engineering Company of Charleston, Mis¬ souri, was employed to make a study of Mississippi River Flood Control as affecting the city of Cairo. His long experience in dealing with Mississippi River flood problems makes his report worthy of careful con¬ sideration. The essential parts thereof with introduction and conclusions by the Division of Waterways are printed as Part II of this report on flood control in Illinois. ILLINOIS RIVER. 19 PART I—FLOOD CONTROL—ILLINOIS RIVER. Prepared Under the Direction of the Division of Waterways of the Department of Purchases and Construction State of Illinois. Mr. L. D. Cornish, Chief Engineer, Division of Waterways, Chicago, Illinois. Dear Sir: Herewith please find report on the “Flood Control of the Illinois River,” consisting of— 1. The general report of the studies, conclusions and recommenda¬ tions, together with maps, tables and diagrams. 2. Appendix “A”—Tables, diagrams and discussion of rainfall on the Illinois River watershed and the relation of rainfall to the Illinois River stages. 3. Appendix “B”—Tables and diagrams of hydraulic data and computations. In writing this report I have used records of daily river stages of the Illinois River and its tributaries for the year 1905 to 1927, inclusive, as kept by the U. S. Weather Bureau, the Engineers of the U. S. War Department, Sanitary District of Chicago, and others, as compiled and furnished by the engineers of the Sanitary District of Chicago. The search thru the surveys, reports, rainfall and river stage and discharge records has been long and tedious and much labor required for their compilation, reconciliation and adaptation to a study of the flood relations, which were most baffling due especially to the numerous, sudden and violent changes in both the stages and the discharge rates of the Illinois River resulting from the breaking of levees and flooding of many levee districts as each major flood has approached its crest. It has been the purpose to present in this report, for future refer¬ ence, all available records and computed data that have been considered as having a bearing upon the conclusions and recommendations herein. In this work, which has required patient and persistent study, I have been ably assisted by Mr. G. W. Pickels, Professor of Drainage Engineering, TTniversity of Illinois, on the rainfall data; by Mr. Murray Blanchard, Hydraulic Engineer of the Division of Waterways, on the discharges, and by members of my organization in developing methods in the solution of the problems presented. To all of them and to other engineers of the Division of Waterways, to the members of the IT. S. Engineer Corps, the TJ. S. Geological Survey, the Illinois State Geolog¬ ical Survey and to engineers of the Sanitary District of Chicago, who have supplied much valuable data and offered many useful suggestions, I wash to express my thankful appreciation. Respectfully submitted, Jacob A. Harman, Consulting Engineer. Peoria, Illinois, April, 1929. 20 FLOOD CONTROL REPORT. FINDINGS AND RECOMMENDATIONS. The following brief summary gives the principal Findings and Recommendations resulting from the study of the Illinois River Flood Problem as disclosed in this report. FINDINGS. 1. The overflowed area in the Illinois River Valley from Grafton to LaSalle represents a total of about 400,000 acres, of which 200,000 acres are now leveed and about 70,000 acres more might be leveed for agricultural or storage purposes. The remainder of the area is water surface in the river and lakes and the narrow areas of land between the river and the levees, or the foot-hills, and is necessary for flood carrying purposes. 2. From Grafton to Otter Creek, about 13 miles, there are no levees. From Otter Creek to Beardstown about 130,000 acres, or 95 per cent of all the available land has been leveed; from Beardstown to Havana 19,000 acres, or 30 per cent of all the available land has been leveed; from Havana to Peoria 37,000 acres, or 73 per cent of all the available land has been leveed ; from Peoria to LaSalle only 2,600 acres, or 4 per cent of all the available land has been leveed. 3. Flood heights have been increased thruout the entire lower valley of the Illinois River by construction of levees. 4. The water diverted from Lake Michigan thru the Chicago Sani¬ tary and Ship Canal increases all stages of the Illinois River the same as an equal added volume from a tributary stream. 5. The flood heights would be much greater from LaSalle to Beard¬ stown if the remaining available open areas should be leveed. 6. The rainfall producing the flood of October 1926 was the great¬ est of record on the Illinois River Watershed. 7. About one-half of the levee districts have been flooded by break : ing of levees as each major flood has approached crest since the levees were built. 8. A number of districts have been flooded by hill streams over¬ flowing the levees before reaching the river. 9. Back-water computations for the discharge of the flood of October 1926, will all levees holding, show that the flood stages along the Illinois River would have been higher if entering the Mississippi River at the 1844 stages, as follows: At Peoria. 0.46 feet At Copperas Creek. 0.80 feet At Havana. 0.95 feet At Beardstown. 1.10 feet At Meredosia. 1.62 feet At Pearl. 3.36 feet At Kampsville. 4.37 feet At Grafton. 8.40 feet 10. High water stages in the Mississippi River produce a back¬ water effect and increase normal flood crest stages on the Illinois River from Grafton to LaSalle. ILLINOIS LIVER. 21 11. The flood discharges of the Illinois River at Peoria and Beard- stown and the present carrying capacity of the river, with all levees holding, are from 10 per cent to 20 per cent smaller than those used in all previous studies for future flood heights. 12. Additional discharge measurements of the Illinois River at flood stages, with all levees holding, are needed to clear up differences in previous measurements not satisfactorily accounted for. 13. The maximum discharge of the Illinois River that may be expected to occur within a period of 100 years, will not exceed the following: At LaSalle . 75,000 cfs. At Peoria . 79,000 cfs. At Havana . 86,000 cfs. At Beardstown. 130,000 cfs. At Pearl . 135,000 cfs. At Kampsviile . 137,000 cfs. At Grafton . 140,000 cfs. 14. The carrying capacity of the Illinois River, as determined by our investigations, indicate that the maximum rate of discharge of the 1904 flood at Peoria was not more than 75,000 cfs. 15. Flood crest storage in leveed areas has little effect upon the further rise of the river after such areas have been filled. 16. The construction of additional levees that would materially re¬ duce the hoodway area and the valley' storage will further increase the flood stages. 17. The most practicable method now available for adequate flood control is the improvement of the Illinois River levee system by enlarge¬ ment and by setting some of the levees back and widening the floodway. 18. The flood stages of the Illinois River in October 1926, with all levees holding, would have been higher, as follows: At Peoria. 1.33 feet At Copperas Creek. 1.92 feet At Liverpool . 1.93 feet At Havana. 1.77 feet At Beardstown. 1.79 feet At Meredosia. 2.56 feet At Valley City . 2.20 feet At Pearl. 2.89 feet At Kampsviile. 1.97 feet 19. Setting levees back as proposed in this report will reduce the maximum flood stages as follows: At Peoria. 1.72 feet At Copperas Creek. 3.00 feet At Liverpool . 2.86 feet At Havana. 2.14 feet At Beardstown. 2.67 feet At Meredosia. 1.98 feet At Valley City . 1.33 feet At Pearl. 0.00 feet 22 FLOOD CONTEOL EEPOET. 20. The average height of the enlarged levees for a miximum flood is 19.2 feet, and the average height for the enlarged levees, with set-backs as proposed, is 17.7 feet, or an average reduction of all levee heights of 1.5 feet, and reductions at Copperas Creek of 3.0 feet and Beardstown of 2.86 feet. 21. The estimated cost of the enlargement of existing levees to grade, three feet above maximum computed flood stage, is $11,500,000 and the estimated cost of enlargement and set-back levees for the same flood discharge is $11,000,000. The total cost of levees to date has been about $12,000,000, exclusive of interest, maintenance and repairs. 22. The levees at Beardstown and the “seawall” recently built by the Illinois Division of Waterways will protect the city against a flood stage 3.6 feet higher than that of 1926 by using flash boards on the “sea¬ wall” as comtemplated. The flood stage at Beardstown with a discharge 20,000 cfs. greater than that of 1926, entering the Mississippi River at 1844 flood stage, and all levees holding, will be 5.2 feet above that of 1926, or with the levees set back, as proposed, 2.5 feet above that of 1926. 23. The levee height of three feet above the flood profile provides an emergency factor of safety of about 10,000 cfs. in added carrying capacity for each foot of levee above flood stage. 24. Until all levees are enlarged to approximately the grade lines as indicated, the weaker or neglected levees will break with each recur¬ ing major flood, and arrest the rise of the river to the extent of the timely storage thus produced. EECOMMENDATIONS. 1. That the system of levees along the Illinois River be placed under more direct control of the Illinois Division of Waterways, or other designated agency of the State, for administration of the improvements and maintenance of the levees in cooperation with the Levee District Officers and the U. S. Engineer Corps and Mississippi Flood Control Commission. 2. That a program for Flood Control should include setting levees back and using at least one of the present levee districts to reduce flood stages. 3. That permits for levees and other structures that may occupy any portion of the floodway be granted only as the public interest may best be served and the benefits will offset the damages, considering the increase in flood stages that may result. 4. That detail study and consideration be given to the economic value of using some of the levee districts and of enclosing some of the remaining overflowed areas for crest storage to reduce floods in con¬ nection with the use of such areas as permanent game and fish preserves. 5. That especial attention be given to obtaining adequate discharge measurements and gauge readings on the Illinois River and its tribu¬ taries to verify or correct the data and conclusions found in this report. ILLINOIS RIVER. 23 SECTION I—GENEEAL DISCUSSION. INTRODUCTORY. The present investigations and report on flood protection in the lower Illinois Valley is concerned with an investigation of works con¬ structed that affect flood heights and a critical review of all previous reports and available data relating to floods. The particular problems considered may be stated as follows: 1. Determination of the magnitudes of the great floods. 2. Carrying capacity of Illinois Eiver as leveed. 3. The effect on flood heights of levees built and possible additional levees. 4. Methods of handling floods. (1) Eaising levees. (2) Setting levees back. (3) Flood crest storage. (4) Tributary stream storage. 5. Comparative costs. 6. Values created or preserved. FLOODS OF THE ILLINOIS RIVER. There are five (5) especially memorable flood years, viz., 1904 before the levee building era; 1913 when about half of the levee districts were completed, most of them being located below Valley City; 1922 when about 90 per cent of the present leveed area had been enclosed, and nearly one-half of that area was flooded by breaks in levees; 1926, with about 180,000 acres enclosed by levees more than one-half of this leveed area flooded; 1927, with all but three or four of the levees which broke in 1926 remaining open. The great flood of 1844, surpassing all flood heights thruout the entire lower valley before the levees were constructed, was exceeded in height at Beardstown and vicinity in 1922, 1926 and 1927. The flood of 1913 showed a very marked effect of levee building upon the flood stages in the Illinois Valley in the vicinity of Beardstown, as compared with the flood stages above Beardstown. The Eivers and Lakes Commission of Illinois published a report on the Illinois Eiver in 1915, which was prepared by Alvord & Burdick, Consulting Engineers, giving a comprehensive study of the Illinois Eiver flood problem. The Alvord and Burdick report predicted future flood heights, as follows: 1. With a discharge equal to that of 1904 entering the Mississippi Eiver at a flood stage of that year, and with the levees of all districts then organized, completed and holding, the stage at Beardstown would be about 3.7 feet above the observed stage, or a reading on the Beards¬ town gage of 23.7 feet. 2. With a discharge the same as that for 1904, but entering the Mississippi Eiver at a flood stage equal to that of 1844 and the levees of all districts then organized, completed and holding, the flood stage at Beardstown would be about 4.0 feet high than that observed, or a stage of 24.0 feet on the Beardstown gage. 24 FLOOD CONTROL REPORT. 3. With a discharge about 35 per cent greater than that of 190-1 entering the Mississippi River at the flood stage of 1904, and levees of all districts then organized, completed and holding, the stage at Beards¬ town would be about 4.4 feet higher than that observed for the flood of 1904, or 24.4 feet on the Beardstown gage. 4. With a discharge about 35 per cent greater than that of 1904 entering the Mississippi River at the flood stage of 1844, and levees of all districts then organized, completed and holding, the stage at Beards¬ town would be about 6.0 feet above the observed stage of 1904. or about 25.0 feet on the Beardstown gage. The flood of 1922 overflowed 21 or 22 levee districts, inundating about 65,000 acres of leveed land and invading the city of Beardstown, approached the maximum stage predicted in the Rivers and Lakes Com¬ mission Report, but did not produce as great a discharge as in 1904. The Chief Engineer of Division of Waterways made a special report on the flood of 1922, and the engineers of the United States War Department made a special report on the same flood in 1923. The floods of 1926 and 1927 exceeded the flood stages of 1922 and caused much greater damage to levees and land in levee districts and to Beardstown and other cities along the lower Illinois River. Considering somewhat in detail the comparative flood stages at Beardstown, where the greatest increase in stage occurs, we find that the flood of 1926 reached a stage of 26.36 feet on the Beardstown gage, which is 5.35 feet above the flood stage of 1904, and 1.65 feet above the flood stage previously estimated by Alvord and Burdick in their report above noted. The effect of levees is thus very definitely disclosed by the ob¬ served river stages, but a satisfactory comparison of the flood magni¬ tudes requires a detail study of the effects of levees on the carrying and storage capacities of the Illinois River Valley. Before entering into a detailed consideration of the surveys and other data available, it would seem desirable to review, briefly, the his¬ tory of the Illinois Valley and its topography, geology and development. WATERSHED MAPS. The watershed of the Illinois River occupies nearly one-half the area of the State, averaging about 125 miles wide and extending from the west central portion northeasterly across the State into Wisconsin and Indiana and touching the Michigan State line. About two-thirds of the area lies south of the Illinois River and about one-third lies north of the Illinois River. The Illinois River is formed by the junction of the DesPlaines and Kankakee, and the other largest single tributary is the Sangamon River entering the Illinois above Beardstown. The accompanying map, Figure No. 1. shows the State of Illinois and the boundaries of the Illinois River watershed, extending into Wisconsin and Indiana. The accompanying map, Figure No. 2, is a larger scale drawing showing the Illinois River watershed, the principal tributaries and sub-tributaries and the drainage areas of the tributaries. This map is reproduced from the data furnished by Illinois State Geological Sur¬ vey Base Map. ILLINOIS RIVER. 25 HISTORICAL SKETCH OF ILLINOIS RIVER. The Illinois River Valley has been the subject of many surveys, in¬ vestigations and reports, but not until after reclamation of a large part of the overflowed area by leveeing for agricultural purposes did the flood conditions become so pronounced and resulting damages so great as to be of general public interest. The Illinois River watershed extends across the middle western and the northeastern portions of Illinois with head waters of the Fox and DesPlaines in Wisconsin and the Kankakee and Iroquois in Indiana. The natural divide between the Illinois River watershed and Lake Michigan in the vicinity of Willow Springs was a low marshy area, which was overflowed by the DesPlaines flowing both to the Illinois River and thru the Chicago River to Lake Michigan. This divide was about eight feet above the low water level of Lake Michigan (1847) and the shortest portage for the water route be¬ tween the Great Lakes and the Mississippi River. In 1673 Joliet and Marquette, going by way of the Fox-Wisconsin route from Green Bay, discovered the Mississippi River and floated down same to the mouth of the Arkansas River. On their return they were persuaded by the Illinois Indians to take the Illinois River and were the first white men to cross the Chicago Divide in September, 1673. Under date of August 1, 1674, Marquette first proposed a canal across the Chicago Divide, in a letter to his friend, Father Dablon, as follows: “A very important advantage, and one which some, perhaps, will find it hard to credit, is that we could easily go to Florida in boats, and by a very good navigation. There would be but one canal to make—by cut¬ ting one-half of a league of prairie—to pass from the Lake of Illinois (Lake Michigan) into the St. Louis River (DesPlaines River). The route to be taken is this: The bark should be built on Lake Erie, which is near Lake Ontario. It could easily pass from Lake Erie to Lake Huron, from which it would enter the Lake of Illinois. At the extremity of this lake would be the cut or canal of which I have spoken, to have a passage to the St. Louis, which empties into the Mississippi. The bark having entered this river could easily sail to the Gulf of Mexico.” In 1679 LaSalle built a boat on the shores of the Niagara River, which was the first vessel to sail the upper lakes. He landed at the mouth of the St. Joe River and established Fort Miami. He proceeded up the St. Joe River and crossed over to the Kankakee marshes near South Bend, Indiana; thence down the Kankakee River and Illinois River to the Illinois villages, where he arrived January 1, 1680. He established Fort Creve Coeur, on the east side of Lake Peoria, which has recently been identified as located on the high bluffs over the bend of the river, just below the city of Peoria. He returned to Fort Miami, going by way of the DesPlaines River to Joliet, thence overland to Lake Michigan, near the mouth of the Calumet. On January 4, 1682, LaSalle proceeded from a rendezvous which he had established at “Chegaugou” on sleighs to Lake Peoria, where he found open water and launched his boats and proceeded southward by the Illinois and Mississippi Rivers, and arrived at the Gulf of Mexico, 26 FLOOD CONTROL REPORT. April 9, 1682. He returned and established Fort St. Louis at Starved Rock, in December of the same year. The DesPlaines-Chicago route was generally used by the early French explorers in passing from the Great Lakes to the Mississippi River. Description of the condition of the Divide is found in the report dated April 4, 1819, of Messrs. R. Graham and Joseph Phillips, as follows: “The route by Chicago as followed by the French since the discovery of the Illinois, presents at one season of the year an uninterrupted boat communication of six to eight tons burden between the Mississippi and the Michigan Lake; at another season a portage of two miles; at an¬ other, a portage of seven miles from the bend of the Plein (DesPlaines) to the arm of the lake. And at another, a portage fifty miles from the mouth of the Plein to the lake, over which there is a well beaten wagon road. Boats and their loads are hauled by oxen and vehicles kept for that purpose by the French settlers of Chicago.” The importance of the Illinois-Mississippi route as a waterway has been advocated since Marquette’s discovery and emphasized by reports recommending the construction of a ship canal across the Chicago Divide from Lake Michigan to the Illinois River. In 1808 a report on “Means of Internal Communication,” by Albert Gallatin; in 1811 the “Illinois Waterway” was reported to Congress in a bill along with the proposed Erie and other canals. In 1822 the United States granted a right-of-way to the State of Illinois to build the Illinois-Michigan Canal through the public lands. From LaSalle to the mouth, the Illinois River had no rapids and it was necessary to construct a canal from the Chicago River through the valley to LaSalle. The State of Illinois started proceedings for the construc¬ tion of the Illinois-Michigan Canal in 1823 and authorized its construc¬ tion in 1829. The work was begun in 1836 and the canal opened to traffic in 1848. The original plans provided for a lake level canal through the Chicago Divide, but on account of shortage of funds plans were modified and the canal constructed with a summit level eight feet above Lake Michigan (low water of 1847—Chicago Datum) with a feeder through Sag Valley from the Calumet River, supplemented by lift wheels at Bridgeport, when the water supply was deficient. The city of Chicago took its water supply, as now, from Lake Michigan and disposed of its sewage through the Chicago River into the lake. The wheels at bridgeport, which were installed to maintain the water supply in the canal, were operated at times to cleanse the Chicago River, and in 1866-1871, the city of Chicago cut the summit level of the canal to the original plan, and the water of Lake Michigan flowed by gravity through the canal to the Mississippi River. In 1881 the Legislature of Illinois, by joint resolution, required the city of Chicago to erect and maintain pumping works at the entrance of the canal at Bridgeport to cleanse the Chicago River and protect the city water supply. These pumps were put into operation in 1884 and continued until the Chicago Sanitary and Ship Canal was completed in January, 1900. ILLINOIS RIVER. 27 As the population and industries of Chicago continued to grow, the amount of water which could be delivered through the canal from the pumps at Bridgeport was not sufficient to cleanse the Chicago River and to protect the city water supply. The sediment partially filled the canal so the carrying capacity became less as the population and demand for more flow increased. The necessity for a better method for disposal of the Chicago sewage, and one which would not pollute the city water supply, resulted in the passage by the Illinois Legislature of the “Act to create Sanitary Districts and remove obstructions in the DesPlaines and Illinois Rivers,” in force July 1, 1889. Under this Act the Sanitary District of Chicago was established by popular vote at the general election on November 5th of that year. The Sanitary District Act provided that, for the purpose of diluting the sewage from the city of Chicago, so it would not be injurious to the health of the inhabitants of the DesPlaines and Illinois Valleys, there should be drawn from Lake Michigan, through the Chicago River and the canal, or canals, to be constructed, 20,000 cubic feet of water, per minute, for each 100,000 population of the Sanitary District. The Act authorizing the organization of the Sanitary District of Chicago provided that the owners of land in the Illinois Valley might recover damages from the district for overflow, due to the diversion of water from Lake Michigan into the Illinois River. The condition of the bottom lands in the lower river valley, prior to 1900, were described in the early reports on the examination of the Illinois River Valley. Captain Howard Stanbury in 1838 described the valley as from one to five miles wide, deeply overflowed in every freshet, filled with bayous, ponds and swamps, and infested with wild beasts; clothed with dense vegetation, which was “a forbidden wilderness ever incapable of inhabitation by man.” General Wilson in his report of 1867, referring to Stanbury’s statement, says, “it may be true in part, but already cultivation has begun to encroach upon the higher bottom lands.” General Marshall in 1890 described the bottom lands and says— “cultivation has extended over the higher bottoms; in fact, it extends everywhere they can get it in seed before the flood begins.” “At about the 12-foot stage, the sloughs, the ponds, the lakes and the lower part of the bottoms are filled; at a 16-foot stage 80 per cent of all the lands that are ever flooded are already covered.” DESCRIPTION OF ILLINOIS WATERSHED. The physical and geological features of the Illinois and its water¬ shed are set out in the Alvord & Burdick Report to the “Illinois River and Lakes Commission” published in 1914, and with slight modifications is herewith presented: The Illinois River is one of the most unusual streams in the United States. Its past importance as an avenue of water commerce, the pos¬ sibilities of its future in this respect, its fresh water fisheries, its use as Note : Additional historical information and references to the early history of the Chicago Divide, and the Illinois River as a waterway, may be found in the “Illinois Waterway Report” by the Internal Improvement Commission of Illinois, published in 1909. FLOOD CONTROL REPORT. 28 . the main sewer (so to speak) of the second city of the country, and more recently, the agricultural development on its bottom lands through the construction of levees, all have led to perhaps more through studies, with various objects in view than has been received by any other of our rivers. The Illinois River is formed by the junction of the DesPlaines and Kankakee Rivers, 273 miles by river above its mouth at Grafton. It flows nearly west 62 miles to the Great Bend near Hennepin, and thence pursues its course nearly south, 211 miles, to its junction with the Mississippi River. Its watershed, estimated at 27,914 square miles, lies principally within the State. The upper waters of the DesPlaines and Pox Rivers drain 1,080 square miles in Wisconsin, and the head-waters of the Kankakee furnish the outlet for 3,207 square miles in Indiana. The principal tributaries are the Kankakee, 5,146 square miles, the DesPlaines, 1,392 square miles, the Fox 2,700 square miles, and the Vermillion, 1,317 square miles, all joining the upper river above Hen¬ nepin. Below the Great Bend the Illinois receives the Mackinaw, 1,217 square miles, Spoon River, 1,817 square miles, the Sangamon, 5,670 square miles and Crooked Creek, 1385 square miles. The remaining watersheds are small, none exceeding 1,000 square miles. About two- thirds of the tributary watershed lies to the southeast. In the lower 60 miles no important drainage reaches the stream from the west, the dividing line between the Illinois and the Mississippi which here flow in parallel courses, lies not more than ten miles westward. The greater part of the drainage area is a typical Mississippi Valley prairie region. The slopes are flat to the north and east, but become more rolling in the lower half of the watershed. The upper waters of the Fox River serve a poorly drained lake region, largely in Wisconsin, and more than half of the Kankakee water¬ shed comprises the marsh region of northern Indiana, now nearly com¬ pletely drained and reclaimed. The dividing ridge of the basin ranges in elevation from 700 to 1,000 feet above the sea, and the river itself from 499 feet at its head to 412-feet at its mouth. . THE RIVER BOTTOMS. From the head of the river to LaSalle, a distance of 50 miles, the fall of the stream is comparatively rapid, dropping about 53 feet. The stream is flanked on either side by bluffs or sharply rising ground no¬ where more than two miles apart, and narrowing to about one-quarter of a mile near Seneca. The bottom lands are comparatively high, and in general rise toward the base of the bluff. High water is of comparatively short duration, and it does not prove advisable to dike the farm land. Below LaSalle the conditions are quite different. In 223 miles the fall is only 33 feet, and for the first 80 miles only six feet. As in the upper river, the bottoms are flanked by bluffs or hills, but the flood plain is wider, ranging from one and one-half to three miles above Peoria, three to five miles near Havana, and six to seven miles near Beardstown, at the mouth of the Sangamon River. In the lower 60 miles, the bottom lands are generally three to four miles in width. From LaSalle to the Mississippi, the bottom land subject to flood aggregates about 400,000 ILLINOIS RIVER. 29 acres or 620 square miles. The immediate banks of the stream are nearly everywhere higher than the bottoms further inland, gradually falling away to lakes, ponds and marshes near the foot of the bluffs. Some exceptions to this rule are found at the deltas of the larger tribu¬ taries. From LaSalle to Beardstown, the river banks lie generally from seven to twelve feet above low water, averaging about ten feet. Many lakes and sloughs between the river banks and the foothills are con¬ nected with the river at low or medium stages of water and lie at approximately the same elevation as the river, rising and falling with it. The low water connection is always at the foot of the lake. At moderate stages of flood they are connected with the river at their upper ends also. The lakes receive and carry a portion of the flood flow in its passage down the valley and, together with the overflow land, act as storage reservoirs, reducing the maximum flood flow rate. Below Beardstown the immediate banks of the stream are higher, the filling of the bottom lands has progressed further, the lakes are smaller, many of them lying 10 feet or more above low water in the main stream. They are thus only invaded by river stages considerably above normal. The course of the river from the Great Bend to its mouth is un¬ usually direct. The fall is so slight that there is little or no erosion of banks or stream beds and sediment brought down by tributaries is not carried very far. Throughout the greater part of its length, particularly in the lower 60 miles, the stream follows the base of the western hills, with occasional diversions toward the center of the valley where the t/ stream has been pushed outward by the deposit at the mouth of an important tributary. Throughout its course the low water banks of the stream are thickly overgrown with trees and brush, and in the lower reaches of the river particularly, the bottoms are. veritable jungles of trees, shrubs and climbing vines. In its natural state all ground within a few feet of the low water line in river and lakes was thus thickly over-grown. The only open places above Beardstown are lakes, ponds and sloughs and their low lying borders submerged for a large part of the year, dur¬ ing the low water season are covered with swamp grass and rushes. Below Beardstown large areas of prairie occupied the level reaches of overflowed valley between the timbered stretches along the banks of river and lakes. GEOLOGY. The geological history of the Illinois River is instructive. It serves to show the reasons governing the peculiarities of the river bottom topo¬ graphy, indicates tendencies still operative, but somewhat modified, and materially assists in final conclusions as to what future floods may be expected, through comparison with other streams upon which longer record periods are available. It seems to indicate why excessive flood rates of some streams are not applicable to the Illinois. In the ice cap period an estuary of the Gulf of Mexico extended north to the vicinity of Cairo, and glacial lobes converged on the low lying region represented by Illinois and the adjacent margins of border- 30 FLOOD CONTROL REPORT. ing states. The topography relief was built up as far south as 37y 2 degrees (Grand Tower to Shawneetown) and the south estuary filled in as the delta or alluvial region of over 30,000 square miles between Cairo and the Gulf. Water passes were carved across the northern highlands and between the lake region and the Mississippi River, from all of which the flow gravitated toward the region of Illinois. The territory drained by the Illinois is almost entirely within the area of glaciation. From the head-waters to Peoria the glacial debris belongs to the Wisconsin period. From Peoria to the southern line of Pike County, the drift is Illinoisan capped along the valley by loess, a fine grained clay-like formation. From this place southward the drain¬ age area is quite small, especially to the west of the river, which is un¬ glaciated, but the surface is largely covered by loess. To the east there is a moderate amount of drift also capped by loess. The visits of the glaciers have had a very marked effect upon the character of the present streams draining the region of their occupation, and the watershed of the Illinois River is principally characteristic of the glacial epoch. The glacial debris overlying rock, with few exceptions, is from. 20 feet to several hundred feet deep, the greater depth predominating. It is well known that when materials are eroded by flowing water, the heavier particles are dropped first and the lighter materials are carried longer distances. Thus, in the valley of the Mississippi River, the upper portion of its ancient channel is paved with coarse sand and gravel. Further southward in Illinois, Iowa and Missouri, the deposits are finer, coarse gravel being scarce. Sand where found is usually coarse to the northward, and becomes finer to the southward. In the lower river the later deposits are of finely divided clay, and at New Orleans for nearly all the year, the water is charged with clay particles so fine that many weeks of settling are required to deposit them. The water has rid itself of sands and gravel, except in the greatest floods. Similar facts are observable in the territory occupied by the glaciers. The rocks over which they moved were worn, scraped and broken, resulting in debris varying from the largest boulders to finely divided dust. The melting waters took up these materials transported them under and through the ice, and upon emerging, first deposited the boulders, then the gravel, then the coarse sand, then the fine sand, and lastly the more finely divided clay. Likewise where the glaciers rested for long periods, in their recession the melting waters deposited all kinds of debris which were washed over by the melting of the ice further north, and the materials were sorted in the order above described, the coarser materials in the north and the finer materials in the south. This sorting of the glacial debris is the principal cause of marked differences in the flow characteristics of the streams in the northern United States. In the north, in Wisconsin and Michigan, and parts of New York and New England, the sands and gravels predominate. For an explanation of the topography of the present river valley, we are also indebted to the research of the Geologists. The sharp dis¬ tinctions between the physical features above and below the Great Bend near Hennepin are explained by the very different geological history of these two reaches of the stream. The lower Illinois from the bend ILLINOIS RIVER. 31 southward occupies its pre-glacial channel which formed a drainage out¬ let for a very much larger area than now drains through this portion of the river. There is circumstantial evidence that the Rock River, now a tributary of the Mississippi, at one time entered the Illinois near the Great Bend, and was subsequently diverted by glacial action. This enlarged drainage area and the great volumes of water that poured from the glaciers serve to account for the wide and deep river valley that was excavated. In places, the prehistoric stream reached a width not less than 15 miles. The present valley, from the Great Bend east, is of more recent origin and owes its existence to its temporary occupancy by the drainage from the glacial Lake Chicago. As stated by Leverett: “This portion of the Illinois Valley, although of Post-Wisconsin age, has a channel of more than a mile in average width and nearly 100 feet in average depth. Yet at present it is the line of discharge for an area of only 12,000 square miles. This influence of the waters discharged from the Lake Chicago and also from the Lobes north and east of the Kankakee is plainly shown in the great size of this valley.” In the escape of these waters it was necessary to cut through a glacial moraine near Marseilles, which for a considerable time, no doubt, impounded a large lake in that part of the river adjacent to Morris. Be¬ low the Marseilles Moraine, the channel was cut to a depth of 50 to 75 feet, and is still cutting, the river running upon a rock bottom. The great quantities of debris brought down by the glacial floods were deposited in the wide and deep valley of the lower Illinois; also, no doubt the scour from the cutting in the upper Illinois. The recession of the glaciers and the resulting diminished floods, particularly, the new outlet formed for the Great Lakes waters at Niagara, a comparatively recent geological event, greatly diminished the water supply and the filling of the Illinois A'alley was not so far advanced as other streams of the Middle West; it remains today only partially filled, with the thread of the stream running substantially straight in its pre-glacial- channel, flanked by numerous lakes and lagoons which doubtless would have been largely obliterated but for the important changes in water supply heretofore mentioned. The building up of the bottom has continued in recent times and is going on today, but the rate of filling is much diminished by the decreased water supply and consists of the finer silt only, which when the flood invades the bottom lands is quickly dropped in the slackened waters and thus accounts for the height of the banks immediately ad¬ joining the stream and the general slope of the land away from the river bank toward the inland lakes. The filling of the lakes is now very slow as much of the water borne material is dropped immediately out¬ side the thread of the channel. In the upper river, although deposits of considerable magnitude took place in the Morris Basin, the more recent period has been one of cutting only. The deposits brought down by the tributaries were largely cut away in the drainage of the Morris Basin, and on account of the more rapid fall in this part of the river, the cutting continues to a relatively small extent. In the lower river the cutting is absent and 32 FLOOD CONTROL REPORT. the bottoms are building, although slowly, by reason of the diminished water supply. WATERWAY IMPROVEMENT IN THE ILLINOIS VALLEY. The Iilinois-Michigan Canal, opened to traffic in 1848 was soon con¬ sidered inadequate for the rapidly developing commerce. The lower Illinois was found too shallow for the boats that would ply the stream. The State built the dams at Henry (completed 1871) and Copperas Creek (completed 1877), and the Federal government at LaGrange (completed 1899) and Kampsville (completed 1893) after }nars of dis¬ cussion and numerous surveys and reports by the engineers of the U. S. War Department. Water from Lake Michigan to increase the low water flow of the Illinois River for navigation purposes has been con¬ sidered necessary since the opening of the Iilinois-Michigan Canal. A Ship Canal or “Deep Waterway” has been the dream of the Illinois Valley Commercial and Industrial interests for more than half a century. Through waterway conventions and general public demand, a deep waterway via the Illinois and the Mississippi Rivers, has been con¬ tinuously before the Congress of the United States and the Legislature of Illinois. More general studies have been made and detailed informa¬ tion obtained regarding the Illinois River Valley than for any other stream of equal length in the United States. Early surveys were made by the U. S. War Department Engineers on which were based the reports resulting in the construction of the Iili¬ nois-Michigan Canal and the four dams in the lower river. The demand for the “Deep Waterway” through the Illinois River after the construction of the Chicago Sanitary and Ship Canal to a navigable depth of 22 feet, resulted in the “Survey and Report on a 14- foot Waterway from Lockport to St. Louis via the DesPlaines, Illinois and Mississippi Rivers” by the engineers of the U. S. War Department by direction of Congress. The surveys were made in 1902-1904. and report published in 1905 as House Document Ho. 263, Fifty-ninth Con¬ gress, First Session. This report included (1) topographic survey of the overflowed lands of the Illinois River Valley, and maps with contour lines at one- foot intervals; (2) river channel soundings; (3) high water and low water elevations; (4) permanent triangulation stations and bench marks for future surveys; (5) compilation of all available river gage readings along the Illinois River; (6) discharge measurements of the Illinois River at a number of stations where long records of river stages had been kept; (7) established river gages during the progress of the survey at many points intermediate to the gages that had been previously kept;. (8) maps and profiles disclosing the results of the surveys and data col¬ lected, and (9) plans and estimates for a deep waterway. In short, this survey and report is a compilation of all the available survey and hydraulic data and has since been used as the basis for subsequent study and plans. Recently, under direction of Congress, re-surveys of the Illinois River channel have been made by the U. S. War Department Engineers ILLINOIS RIVER. 33 for construction of a nine-foot waterway from Utica to St. Louis, report dated May 11, 1928, House Document Ho. 12, Seventieth Congress, First Session, Committee on Rivers and Harbors. Meanwhile, the State of Illinois is constructing a nine-foot water¬ wayway from Lockport to Utica with mitre-sills 14 feet below water level to be completed and open for traffic in 1931. SOURCES OF INFORMATION. Sources of information referred to or used in these studies include reports of U. S. Weather Bureau, United States Geological Survey, U. S. War Department Engineers and by several Departments of the State of Illinois, among which are the following: 1. Report of the Illinois State Board of Health on the sanitary conditions of the Illinois River with special reference to the effect of the sewage of Chicago, prior to and after the opening of the Sanitary Canal, published 1901. 2. Report of the U. S. War Department Engineers on the 14-foot waterway from Chicago to St. Louis by way of the Illinois River, House Document 263, Fifty-ninth Congress, First Session, 1905. 3. Report of the Internal Improvement Commission of Illinois for a “Waterway from Lockport, Illinois, by way of the DesPlaines and Illinois Rivers,” 1909. 4. Report of the Rivers and Lakes Commission of Illinois giving river discharge measurements, river stages, etc., of the Illinois River and its tributaries and other streams in the State, prior to and includ¬ ing the year 1911, published in 1914. 5. Report of Rivers and Lakes Commission of Illinois, prepared by Alvord & Burdick, on “The Illinois River and its Bottom Lands, with reference to the Conservation of Agriculture and Fisheries and the Con¬ trol of Floods,” 1915. 6. The Illinois State Geological Survey Report on “The Drain¬ age Districts of Illinois,” Bulletin No. 42, published 1921. 7. Report of the Division of Waterways, by M. G. Barnes, Chief Engineer, on “Flood in Illinois in 1922.” 8. Report of the engineers, U. S. War Department, on “Flood Control of Illinois River,” 1924, House Document 276, Sixty-eighth Congress, First Session. 9. Gauge readings and discharge measurements by the engineers of the Sanitary District of Chicago. 10. The U. S. Weather Bureau climatological reports of daily rain¬ falls at the stations where records have been kept in Illinois, Indiana and 'Wisconsin, on and adjacent to the Illinois River watershed, furnish the information on which are based the rainfall studies herein discussed. Since 1908 the United States Geological Survey has been co-oper¬ ating with the State of Illinois in making discharge measurements and keeping gauge records of the Illinois River and its tributaries. This co-operation was begun under the Rivers and Lakes Commission and has been followed by the Division of Waterways since the merging of the work of the Rivers and Lakes Commission with that Division. —3 F C 34 FLOOD CONTROL REPORT. Based on these discharge measurements, the United States Geo¬ logical Survey has prepared rating curves, and from river gauge readings daily discharges have been tabulated for practically all of the gaging stations on the Illinois River and its tributaries since this co-operative work was undertaken. These discharge measurements are published from year to year in the United States Geological Survey Water Supply Papers Series. The Illinois State Geological Survey and the United States Geo¬ logical Survey have been co-operating for a number of years in mapping the State of Illinois. This work has progressed to a point where a large part of the Illinois River watershed has been surveyed and maps made showing drainage and elevations by contours at intervals of ten (10) feet on maps drawn to a scale of about one inch, per mile. These maps show the locations of buildings, roads and other public improvements, and the topographic features essential to the development of preliminary plans for drainage and flood control works. RIVERS AND LAKES COMMISSION REPORT, 1915 (BY ALVORD AND BURDICK.) This report shows that by the year 1914 levees had been built in the Illinois River Valley, reclaiming about 150,000 acres of the overflowed land, and levees were then in process of construction for reclaiming about 20,000 additional acres, or a total of 170,000 acres. The rainfall from 1890 to 1900 was below normal and from 1900 to 1910 was above normal. The greater rainfall and the diversion from Lake Michigan through the Chicago Sanitary and Ship Canal, together with leveeing of nearly 50 per cent of the overflowed lands in the Illinois River Valley caused much higher flood stages and more frequent overflow. The questions to which that report was addressed are as follows: 1. “What future flood rates may reasonably be expected on the Illinois River? 2. “Is the present waterway sufficient to accommodate the future floods ? 3. “What interests are affected by the past and probable future improvements in the valley? How is each interest affected and what is the relative importance of each? 4. “What plan can be followed to correct the deficient waterway and to produce a maximum benefit to the local interests and to the public ?” Among the conclusions and findings we would note particularly, as bearing upon the present flood situation in the Illinois Valley, the following: 1. “Past Floods. —We conclude that the flood of 1904, which at most places upon the river is the greatest flood of recent years, reached the rate of about 80,000 c. f. s. at Peoria and 125,000 c. f. s. at the mouth of the river. These rates are equivalent, respectively, to 5.94 and 4.48 c. f. s. per square mile of drainage area. “At nearly all places upon the river the flood of 1844 reached a greater height than any flood of record before or since. This flood occurred during the maximum flood upon the Mississippi, and the water passed through a river valley entirely unimproved, very likely a veritable ILLINOIS RIVEIL 35 jungle. Under all these circumstances, it is questionable if the flow rates in the 1844 flood very much exceeded those in 1904.” 2. “Present Waterway.— In a state of nature the river in flood occupied its entire valley from hills to hills. For many miles in the lower river this flood plane averaged three miles in width and in the great floods from seven to nine feet in depth. “In the lower one-third of the river, farm land levees have reduced the width of the flood plane by about 80 per cent and have reduced the cross-section of the flowing stream in a great flood to about 25 per cent of the available cross-section of the 1904 flood. “Although a large part of the flood flow has always passed by way of the channel, the velocity being comparatively slow upon the land, it is our conclusion that the farm land levees are a menace to themselves, in that they have so restricted the flood water channel and are lacking in height, generally speaking, to such an extent that they are likely to be overtopped in a great flood. As the protection afforded to different dis¬ tricts is quite variable, it is evident that the lowest levees will suffer first and will tend to protect the higher levees. If all the districts are to be protected, a greater available flood cross-section must be provided which may be accomplished in several ways, or the flood rates must be reduced through storage.” 3. “Interest Affected.— Although many interests are affected to a minor degree, we find that the predominant interests in the river valley are agriculture and fishing. There are other important interests at Peoria and at a few of the other cities bordering the stream. These cities, however, without important exceptions are well above the ordinary floods and the municipalities in general are not greatly concerned with flood abatement.” 4. “Flooded Lands.— We estimate the total water acreage below LaSalle in the flood of 1844 at 397,980 acres. Of this acreage 320,150 acres was flooded land. The first total includes 28,490 acres of river surface and 49,340 acres of lakes adjoining the river, the river and lakes surface being measured at the low water plane in 1901.” 5. “Levee Districts. —Since 1904 the construction of levees for the protection of the bottom lands has proceeded at a rapid rate. At the present time nearly all the bottom land below Beardstown has been reclaimed. The total leveed lands are estimated at 171,725 acres. These lands have been protected from floods at an estimated cost of $5,350,000, or about $30.00 per acre. The estimated full value of these lands is about $19,000,000, an average of about $112.00 per acre. Much of this land is valued at from $125.00 to $150.00 per acre.” LEVEE DISTRICTS IN THE ILLINOIS VALLEY. Considerable areas of the higher lands in the overflowed portion of the Illinois Valley had been cleared and put into cultivation prior to the waterway survey for the 14-foot waterway by the U. S. Engineers in 1902 to 1904. Levees had been constructed in the lower Illinois Valley by three organized drainage districts and by five private owners, as follows: 36 FLOOD CONTROL REPORT. Organized Districts, 1904. Acres. 1. Pekin & LaMarsh District, opposite Pekin. 2,300 2. Lacey (and Langellier) District, opposite Havana. 5,100 3. Coal Creek Drainage District, opposite Beardstown. 6,700 -14,100 Acres Private Levees, 1904. 1. Kaiser or Roberts Ranch, below Pearl...... 3,300 2. Hartwell Ranch, below Pearl. 5,500 3. Reach Ranch, below Pearl. 1,200 4. Spankey, below Kampsville. 900 5. Rosedale, below Hardin. 285 - 11,185 Acres Total . 25,285 Acres The Pekin and LaMarsh District, Lacey District and private levees were all overflowed in 1904, and only the Coal Creek District was pro¬ tected against the 1904 high water. Since 1914 a number of additional levee districts have been organ¬ ized and constructed and there are now remaining six (6) areas along the Illinois River that might be leveed for agricultural purposes or for flood peak storage, located as follows: 1. Meredosia Lake Region, about. 8,000 acres 2. The Delta of the Sangamon River from Bath to Beardstown, about . 40,000 acres 3. Waukanda District, immediately below Liverpool, about. 6,000 acres 4. East side of the river, from Spring Bay to the Sante Fe Railway, opposite Chillicothe, about. 6,000 acres 5. Sparland District, about. 2,500 acres 6. Lake Senachwine Basin, about . 12,000 acres Total . 74,500 acres The Hennepin District on the east side of the river, just below Hennepin, containing about 3,000 acres, is the only effective levee dis¬ trict between Peoria and LaSalle. The levees of the Partridge District, opposite Chillicothe, were destroyed by wave action and the district has been abandoned. The Chautauqua Drainage District, containing about 3,500 acres, just above Havana and opposite Liverpool, was overflowed in 1926 and the levees have not been repaired. This district would add about 3,500 acres to the overflowed area available for flowage and storage if the levees are not restored. The entire area of the lower Illinois Valley subject to overflow, from LaSalle to the mouth, was about 400,000 acres, of which about 70,000 acres was water surfaces in river channel and lakes, the land subject to overflow being about 330,000 acres. The area of levee districts completed, or under construction in 1914, was about 150,000 acres. Shortly thereafter additional levees were com¬ pleted covering about 18,000 acres, or a total of about 168,000 acres. There are now 38 active organized levee districts and three private levees enclosing about 200,000 acres of Illinois River bottom lands leveed. There are also several districts lying near the foot-hills, organ¬ ized to protect the land from overflow of the tributary streams, and to some extent from back-water of the Illinois River. Tables, No. 1 to No. 4, inclusive, are a list of the levee districts giving the name of the district, the county in which the district is located, the area, cost of improvements and other statistical data. From LaSalle to its mouth the flood plane of the Illinois River is from one mile to seven miles wide, generally ranging from two to four miles in width, and is divided by deltas of the tributary streams into four distinct reaches, which are most conveniently designated, as follows: ILLINOIS RIVER. 37 1. From LaSalle to Peoria, containing about 53,000 acres of bot¬ tom land, subject to overflow, in which there is one effective levee dis¬ trict just below Hennepin of 2,610 acres. Levees were constructed to reclaim about 3,000 acres opposite Chillicothe by the Partridge District, but these levees have been destroyed by wave action and the work abandoned. 2. From Peoria to Havana, containing about 51,000 acres of bot¬ tom land, subject to overflow, of which about 37,000 acres is in nine (9) organized levee districts and about 14,000 acres not leveed. 3. From Havana to Beardstown, containing about 63,000 acres of bottom land subject to overflow, including the delta of the Sangamon Kiver, of which about 19,240 acres is in nine (9) organized levee dis¬ tricts and about 43,760 acres not leveed. 4. From Beardstown to Grafton, containing about 166,000 acres of bottom land subject to overflow, of which about 130,000 acres is in nineteen (19) organized levee districts and about 36,000 acres not leveed. Of the 36,000 acres not leveed, 31,000 acres lie between the last levee district and the mouth of the river. It will be noted that 4 per cent of the bottom lands subject to over¬ flow, between LaSalle and Peoria, has been leveed, about 73 per cent between Peoria and Havana has been leveed, about 30 per cent between Havana and Beardstown has been leveed and about 78 per cent between Beardstown and Grafton has been leveed, or 95 per cent of the latter area has been leveed between Beardstown and the lower end of the last levee district. The levees have reduced the space available for flow and for storage, which has the effect of increasing flood stages. TABLE NO. 1—DRAINAGE DISTRICT STATISTICAL DATA, ILLINOIS RIVER VALLEY. 38 FLOOD CONTROL REPORT. 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(B 1 = a <0 oh , CO ^ aM § -* o Z ^ > Fh o 73 © 73 > o u ft Fh o & 00 c © © 73 c o c CO © o 73 CM CM 05 T-H © © c 00 © ^3 © • 73 73 a c$ 00 © © © c © © b£) Fh "2 © T3 c a CO Fh 5 ft © Fh H-5 CO o © © -a Eh w H o IOCDNOOC50*H CO CO CO CO CO ^ ^ TABLE NO. 4—DRAINAGE DISTRICT STATISTICAL DATA, ILLINOIS RIVER VALLEY. 44 FLOOD CONTROL REPORT. 71 gj O cq ^ •gfss ^S| oooooooooo^ O^OiOMOOiOOO 2 p IOCD(NCCN05000COCO O COiCCOCOOqiONiOiOiM^ o o o « o o o 10*000*00*0*0*0 i ' 00 1 *C CO 05 i0500T-HOT-nocqo i 1 Tf i t-h n cq i t-h co co ^h cq *o t-h t-h i i cq o o o o o th !>- o o o o cq cq 05 ^h HHOO Cq o Eh o t- o P fn o a ooooooooooo ooooooooooo MNrt ^ p o - HH 71 -+H GQ o o oooooooooo oooooooooo ocqoooooooo o O !>• O *0 O O O O O O \— r OiOONiOiOOOO»C^ - oo oo 00 Tt'HOO o»o HCOHIN 73 p o -Q o* H 0000*000000 oooooooooo 0*0*000000*00 O O t''» CO *0 *0 O O <0 OO O htt OOt^t^CqOOOOO^H CKN'tCOlMCOONNO 05ooocoooo^05oqoo t-h t-h oo co cq t-h cm cq oooooooooooooo oooooooooooooo oooooooooooooo oooooooooooooo OOOOOC0OOC5OOOCCO oooooooo oooooooo oooooooo oooooooo OOOOOOx^T-H O O O CO O Tf 05 h CO O t-h cO CO O ccdoxcqo^x^oxocqo cq cq t-h co cq *o t-h t-h t-h COrHCqtNOXXrfH cq OOOOC 5 H co co co cq co O *o o o no o o o o o o -p O CO o o co o o o o o o __ 3 o CO *o o co o o o no no o P o Tf CO *0 *o o o o oo CO o H— 1 a o CO cq CO T-H o CO 05 o 71 cq Tf Tf *o o 05 co Tf o Tf 05 cq Tf cq 05 00 05 CO Cq cq 71 cq T-H T-H cq 05 Tf CO T-H cq Tf GQ P oooooooooooooooooooooooo oooooooooooooooooooooooo ooooooocooqooooooooooooooo 0000000»005i00b-000000000000 lOOOOCOCOCOfNCSO^OOOOiCOiOOOOOON TPOOOCOO»005NHCONHICOION(N(NHCO(NCCO ocoNco^iocOTPONiCTHrPGscofNcoo cq Tf cq CO CO cq dHHCqHCOHC^ t'— T-H t-H t-h t-h t-h I>- t-h Ht^ Tf r)1 i>- 3_.s 333 2 O 2 w ~ g o S ftr, <1 .2 O *0 O O O O O 'O'O o o OcOOOOOO ^ o o o P OOOOOOOO 00*00 OCOOOOOOH^OCOO 0*OOOOCOt-h^OC50 o cq o 05 oo co co OrpiOCOOHTji t— T—I 'Tp co co cq Tf O' cq o o o o o o o o o o o o o o o o o o o o O O 05 o o O *0 CO O T-H IONOCOCO oooooooooo oooooooooo cqooooooooo OOOOOOOOOO cqoo*ooooooo COiOXCOiOCOOiC^H cqcqo5cococococqcqoo o o o o o o o o o o o o o o o o o o o o O O O Tf co 05 CO Hp T-H 05 CO Tf CO Tf «rf p P o o o> i a> 3 pj a> '£ a> NON 3 c 3 a) c 3 P-i E—' P-i F—< c 3 3 3 o +-> Tl —hCii'IIIIIIII^^h^iI^h or! p i • ! i » ' i ' » i iOOO) i • O i i I \ \o m \ \ \ i i *-h «-rt i i i 1 ;PQ 3 ! ! ! 1 1 o 1 1 o 1 l L- : \o '■c ; os : : ! : is J 3 3 ' 3 3 ! ! ! 1 1 Pi i | tf 3 c 3 c 3 3 c 3 c 3 i ' i ^ m n co O' (O O r\ r\ /-s J -+a +3 ® -u K/ r\ •« » o • r—I f-l H-5 71 • l-H tp *+-< o o a P £ CQ P .S S'SrgJee ajpu A >» M <3^1 ac^ S 03 3s3 ® s_ 3 oj ® cj o> O o,o 3 o 3 . o c a l* ® ■ > 9 e 3 ffi.li ^ ei ft ■ c 31—3 h Q-p in 3 o 3 cal |8tf 3 « o ° O o ^ oou 0,03 C3 .h'^-^ £ art O o 2 § X Co S3 p §1 o c3 p & o HH • 71 . - .T^'-P r^H O O 2 o p p o I tl 3- 0 ) M TJ p c 3 L- o M o ^ . O o o o d) J-4 *-q' Cl> ® > 5s 3 >1 r* O r-» H -5 ^H r-> . pH T 3 t- a> t-. 3'C Js 3.”3 p< '•s'“ u n u ^ a 2r90 i & j a o ©pH^ao^is oPh^ °-^r3 c S ^ S'eS-SPS o £ Hcqco^kooNxo50' -ooo50^Hcqco’Tfiocot>-coo50T-HC s qco'Tfioco iPHHHrHHHrHHcqcqcDNcqcqcqcqcqcqxcoMcocococo ILLINOIS RIVER o o o o o OCONCOh COO5O5C0IN CO r-4 CM CM r-H O o to o o o o o o o o o o o o o o o O O O CO o O O 05 to to CM Tf CO CO <-h to CM CO CO CM 1—H o o o o o o o o o o o o o o o O O O CO o O 1—i CO OO 05 O to i-H ir^ to CO to CM CO CO o o o o o o o o o o o o o o o O O O -H o O CO 00 00 05 WNrHCMtO to O CO Tf* Tf’ CO CM Tf ^ o o o o o o o o o o o o o o o O O O OO o O OO to 05 o CO CM O O 05 to I I o ' o I to ' to o o (D O 3) (D k 0 0 0 0^ O O d) (D »_ t_ t_ frH oooo^ + 4-73 ' >> s •+3 O P > b rt -3 oS 13 WWWtelz; NOOOiOh CO CO CO Tt< -41 p a p & £ & o o o PPG PPG PPG (DOG t— t— t- P P P +-> 73 73 X) PPG a> p a> Oh Qh Ch XXX PPG. < 4—1 «-l—< o o o -HJ -W p c a PPG o o o S S S Cj Cj cj I I I >OCMN CM CM ’-h 05 05 05 r—H t-H T-H o o rG£lX 2 a; a; -+_> c3 c3 c3 *E *fn ’C Q< 0 0^0 *Jh 'C ‘C - 4— 1 • 4 —' 4 —> CO CO CO qqq 46 FLOOD CONTROL REPORT. AEEIAL PHOTOGRAPHS OF THE 1926 FLOOD OF THE ILLINOIS RIVER. At the height of the flood of 1926, October 14 and 15, the Division of Waterways procured a series of aerial photographs covering the Illi¬ nois from Peoria to Naples. These photographs illustrate more clearly than any other means the extent of the flooded area and the levee dis¬ tricts which were overflowed. Several of the photographs illustrative of the conditions, and which show some of the critical reaches of the Illinois River, are reproduced: Picture No. 1 (Record No. 4791) October 14, 1926, is a view look¬ ing up the Illinois River from a point just above Pekin showing the overflowed valley with Bartonville and Peoria in the distance. The bend of the river at the lower end of the citv of Peoria, and the extent of the overflowed area covered by timber are clearly shown. At the lower left hand corner of the picture is shown the upper end of the levee of the Tuscarora Drainage and Levee District, an extension of the Pekin and LaMarsh levee. PICTURE NO. 1. Looking up the Illinois River just above Pekin. ILLINOIS RIVER. 4 ? Picture No. 2 (Record No. 4709) October 14, 1926, is a view look¬ ing northwest showing the levee at the south end of the Chautauqua Drainage District on the east side of the river, about four miles above Havana, and the Thompson Lake District i* the background on the west side of the river. This view shows the Chautauqua District flooded with the water near the top of the levee and crevasses thru which the water is flowing. This indicates that after the Chautauqua Drainage District levees broke there was a very considerable flow thru the area of the district. PICTURE NO. 2. Looking northwest about 4 miles above Havana. 48 FLOOD CONTROL REPORT Picture No. 3 (Eecord No. 4765) October 14, 1926, is a view look¬ ing northeast with a portion of the city of Bearclstown in the lower right hand corner. The Lost Creek Levee District in the center fore¬ ground and a large area of developed farm lands on the second bottoms north of Beardstown, which are not overflowed until the river passes a stage of 20 feet on the Beardstown gage. PICTURE NO. 3. Looking northeast of Beardstown ILLINOIS RIVER 49 Picture No. 4 (Record No. 4759) October 14, 1926, is a view look¬ ing up-stream showing the river channel, Coal Creek Levee District and the South Beardstown Levee District levees, the open borrow pits along the levees, the heavy fringe of timber between the river channel and the borrow pits, with Beardstown in the upper right hand corner back¬ ground. Attention is directed particularly to the heavy growth of timber along the river bank, which is relied upon by the districts to protect the levees from erosion by wave action. PICTURE NO. 4. : : '■%ywys. Looking Upstream above Beardstown showing River Channel. — 4 ¥ C 50 FLOOD CONTROL REPORT Picture No. 5 (Eecord No. 4754) October 14, 1926, is a view look¬ ing up-stream with the LaGrange Locks and Dam at the left center, showing the overflowed area opposite the locks, with Meredosia Lake Drainage and Levee District in the upper right hand corner and the South Beardstown Drainage and Levee District in the upper left hand corner. This picture also illustrates the extent of growing timber in the unleveed overflowed area. PICTURE NO. 5. Looking Upstream with the La Grange Lock at left center, ILLINOIS RIVER. 51 Picture No. 6 (Record No. 4747) October 14, 1926, a view looking up-stream shows the city of Meredosia at the right, and in the foreground the Wabash Railroad Bridge, the McGee Creek Drainage and Levee Dis¬ trict with the levees broken and district flooded—Meredosia Bay and the overflowed area in the central background, the Meredosia Drainage and Levee District in the right central background, and the South Beardstow'n Drainage and Levee District in the distant background. PICTURE NO. 6. Looking Upstream showing Meredosia at right. 52 FLOOD CONTROL REPORT. PROFILE OF PRINCIPAL FLOODS. Drawing, Figure No. 3, shows the high waters of the Illinois River from Grafton to LaSalle for the 1844, 1904, 1922, 1926 and 1927 high waters, and the low waters of 1901 and 1922. STRAIGHTENING TRIBUTARIES. The flood stages in the Illinois River are also modified by straighten¬ ing the channels of the tributaries, thus hastening the discharge of the flood waters into the Illinois Valley. Between the years 1900 and 1910 the Sangamon River channel was straightened for a distance of about 40 miles, ending at the eastern edge of the Illinois Valley. Considerable stream straightening has been done in numerous other portions of the Illinois River watershed. While the effect of stream straightening is to hasten the delivery thru the straightened portion of the channel, there is no available data by which it can be determined with certainty that the discharges or stages of the Illinois River have been increased because of this work. FLOOD CREST TRAVEL. An examination of the hydrographs of the Illinois River showing the daily stages at Grafton, Pearl, Beardstown, Havana, Peoria, LaSalle and Morris, from 1890 to 1927, inclusive, discloses that the flood waters from the tributaries below the Sangamon are always discharged ahead of the flood crest above Beardstown. The Mississippi River at Grafton frequently reaches crest stage and is falling by the time the Illinois crest reaches Beardstown. LEVEE DISTRICTS FLOODED. In each of the three major floods since 1913, viz., 1922, 1926 and 1927, about one-half of the levee districts were overflowed. In some of these districts the levees were broken at two or more places so the water flowed thru, thus increasing the carrying capacity of the river. All of the districts that were overflowed furnished storage as the river was approaching crest, materially reducing the stage to which the river would otherwise have risen. For the 1926 flood detailed estimates and profiles, appearing later in this report, show the additional rise which would have occurred if the levees had been high enough and had held. Maps have been prepared showing the location of the levee districts in the Illinois Valley as they existed in 1904, Figure No. 4; 1913, Figure No. 5, and 1926, Figure No. 6. On these maps are also shown in colors the dis¬ tricts which were flooded and those which were not flooded. A record of the drainage districts which were flooded in 1922 and 1926, with the dates so far as available, on which the levees broke is given in Table No. 5. DIVERSION OF WATER FROM LAKE MICHIGAN. Water from Lake Michigan has been flowing by gravity thru the Illinois River since 1871 when the summit level of the Illinois-Michigan Canal was lowered by the city of Chicago for sanitary drainage. The outlet for the sewers of Chicago was for the Chicago River which flowed ILLINOIS RIVER. 53 into Lake Michigan, but the current was not sufficient to cleanse the river. The city of Chicago has always taken its water supply from Lake Michigan and the sewage contaminated the water supply. Because of these conditions the current of the Chicago River was reversed so as to flow from Lake Michigan thru the Illinois-Michigan Canal and the DesPlaines River to the Illinois River. This was accomplished by lower¬ ing the summit level of the Illinois-Michigan Canal at the expense of the city of Chicago, which was completed in 1871. Within a few years the sewage increased to such an extent that gravity flow thru the Illinois- Michigan Canal was not enough to cleanse the Chicago River and keep sewage from entering the water supply intakes. In 1881 the Legislature of Illinois required the city of Chicago to erect a pumping plant at the entrance of the canal to the Chicago River at Bridgeport to increase the flow of water from Lake Michigan and cleanse the Chicago River by pumping into the canal. These pumps were put into operation in 1884 and continued until the opening of the Chicago Sanitary and Ship Canal on January 17, 1900. Since that time water has been flowing from Lake Michigan thru the Chicago River, the Chicago Sanitary and Ship Canal and the DesPlaines River into the Illinois. TABLE NO. 5—LEVEE BREAKS—1922. District. Date of break. Station. Length. Atkinson Lake*_ No data... Banner Spl_ - .. Not flooded__ Beardstown City_ 32+00 Big Lake_. _ Not flooded_ Big Prairie_ _ Not flooded_ Big Swan _ Not flooded_ Chambersburg*_ No data... Chautauqua_ 49+16 664' Chautauqua. _ Apr. 7, 1922_ 260+23.5 205' Chautauqua. _ 409+22.5 335' Coal Creek__ Apr. 16, 1922_ N. 94+46.5 535' Cook*__ Apr. (14 or 15) 1922_ Cook*. 13+85.5 53+71.5 127' 250' Coon Run___ Was all flooded in 1922_ Crane Creek_... Apr. 20, 1922_ 197+36.5 597' Dickson*... 76+65 Dickson*_ _ ... Apr. 13, 1922_ 24+37 57' Eagle Run*. _ No data. _ East Liverpool. . . Apr. 3, 1922_ 46+22 230' East Peoria_ Not flooded. Eldred_ Not flooded.. Fairbanks__ . _ Apr. 10, 1922_ 109+33S 362' Hartwell. . _ .. Apr. 19, 1922_ 149+63 230' Hennepin..._ Not flooded__ Hillview . _ Not flooded__ Indian Creek*__ No data.. Kelly Lake__ Apr. 14, 1922_ 182+22 28' Kelly Lake_ __ Apr. 14, 1922. 52+54 232' Kerr.. .. Apr. 14, 1922.. 8+72 36' Kerr. . . Apr. 14, 1922_ 55+57.5 95' Kerr Crane__ Apr. 14, 1922_ 128+80 125' Kerton Valley. Not flooded Keystone S. & W. Co*... Not flooded .. .. Lacey-Langellier_ Liles-Metz*_ Not flooded .. Probably flooded, but no data_ Liverpool_ Apr. 1, 1922_ Levee not to grade No. 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Date repaired. Previous to Oct. 1, 1922. Previous to Mar. 12, 1923. Previous to Mar. 14, 1923 . Previous to Mar. 17, 1923 . 1922. Prior to Nov. 8, 1922. Prior to Nov. 8, 1922. Prior to Nov. 10, 1922. Prior to Nov. 15, 1922. 30, 1922. 'ernporan 1922. Partly filled Oct. 27, 1922. 54 FLOOD CONTROL REPORT TABLE NO. 5—Continued. LEVEE BREAKS—1922. No. 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 District. Date of break. Station. Length. Lost Creek_ Apr. 11, 1922_ East levee flooded around end of levee or through C. B. & Q. R. R. tracks at Beardstown. No data Lynchburg*_ Apr. 13, 1922_ Old Mauvaisterre_ Mauvaisterre_ No data, but was flooded_ Apr. 16, 1922_ Overtopped Naples C ity and le McGee Creek_ Not flooded_ Meredosia Lake_ A. J. Metz*.. Apr. 19, 1922.. Flooded but no d Apr. 16, 1922_ 63+01 efinite information.. 388' Naples City*_ 71+50 Nutwood_ Not flooded_ Partridge*_ . Abandoned__ Pekin and LaMarsh. Robley*... Apr. 12, 1922. Apr. 17, 1922. 13+50 (R. R. tracks) 135+54 V. o o lO Rocky Ford_ Not flooded_ Schaeffer*.. Apr. 11, 1922_ 44+27 flooded_ 38' Schulte*_ No data, but was Apr. 19, 1922. Scott Co_ 435+58 144' Seahorn..__ Not flooded_ South Beardstown.. Spankey_ Not flooded_ Apr. 22, 1922_ 60+32 151' Spring Lake_ Not flooded_ Spring Run*_ No data.. __ Thompson Lake_ Tuscarora*_ _ Apr. 10, 1922_ Built in 1925_ 263+69.5 261' Valley_ Not flooded_ Valley City... Not completed West Matanzas __ Not flooded_ Wilson Ranch*_ Apr. 17, 1922. 34+55.5 vailable.... 164' Wolf Creek*_ No information a No information a Youngs* __ vailable_ Date repaired. vee south of Smith Lake. Partly filled Oct. 12, 1922. Previous to June 27, 1922. Flooded around end. Previous to Aug. 12, 1922. Oct. 4, 1922. Previous to Sept. 7, 1926. Previous to Mar. 8, 1923; levee not to grade. Began filling Aug. 1, 1922; working, Aug. 8, 1922. * Several small districts, nearly all private, have been included in Table No. 5, which were not in¬ cluded in Tables Nos. 1 to 4. TABLE NO. 5—Continued. LEVEE BREAKS—1926. No. 1 2 3 4 5 6 7 8 9 10 11 12 13 District. Date of break. Station. Length. Atkinson Lake* No data. __ Banner Special.._ Previous to Sept. 18, 1926.. 445+26S 112' Banner Special_ Previous to Oct. 18, 1926_ 421+50S 420' Banner Special_ Oct. 6, 1926_ 225+45S 636' Banner Special_ 34+40N 200' Beardstown City_ Sept. 3, 1926_ 32+00 Water ove Big Lake Not flooded_ Big Prairie . Not flooded_ Big Swan Sept. 3, 1926_ Near 100+00E Big Swan Sept. 3| 1926. W17+00 Big Swan Sept. 8, 1926_ 582+50 Big Swan Sept. 8, 1926_ 622+26 to end Chambersburg*.. .. Not known_ 6 breaks between sta- tion 16+45 and 62+82 587' Chautauqua (1) Oct. 9, 1926_ 313+00.7 440' Chautauqua (2). Oct. 9, 1926_ 327+41 182' Chautauqua (3)... . Also broke along north and south levee s in 1926 Coal Creek Not flooded__ Cook*__ Oct. 3, 1926_ 201+50 128' Coon Run_ 103+45 30' Crane Creek Not flooded Dickson*_ Engineer at Cook district thought it br oke about 1 week previous to October 2d. Date repaired. Previous to Feb. 7, 1928. Previous to Feb. 7, 1928. March, 1928. March, 1928. rtopped entire levee. Previous to Oct. 8, 1927. Previous to Oct. 8, 1927. Previous to Oct. 8, 1927. Previous to Oct. 8, 1927. Previous to June 1, 1928. Not filled Mar. 1, 1929. Not filled Aug. 3, 1927. Previous to Sept. 24, 1927. ILLINOIS RIVER. 55 TABLE NO. 5—Continued. LEVEE BREAKS—1926. No. District. Date of break. Station. Length. Date repaired. 14 Eagle Creek*_ No data 15 East Liverpool_ Oct. 5, 1926... 290+30 271' Repaired 1929. 1927. 16 East Peoria_ Not flooded in 19 26; flooded from Farm Creek in 17 Eldred. Not flooded.. 18 Fairbanks.. Oct. (2 or 10), 1926 Sept. 8, 1926_ 529+00 North end 130' Oct. 16, 1926. urricane Creek. 19 Hartwell_ 682—Northeast end— —from H 20 Hennepin.... Not flooded .. .. 21 Hillview__ Sept. 4, 1926 Southeast end Prior to Oct. 13, 1927. Prior to Oct. 13, 1927. Hill view_ Sept. 8’ 1926 70+00 Southeast end Hillview__ Oct. 3, 1926. Prior to Oct. 13, 1927. 22 Indian Creek* . No data, but was Oct. 6, 1926_ flooded_ _ _ 23 Kelly Lake.. 52+00 200' Prior to Jan. 1, 1929. 24 Kerr (1)_ Oct. 5, 1926 115+42 265' Prior to Mar. 1, 1928. Kerr (2).__.. Sept. 15 , 1926 North end by creek 25 Kerr Crane_ Sept. 15, 1926; Oct. 5, 1926 Through Kerr district 26 Kerton Valley_ Oct. 7, 1926_ Levee did not break. Flooded through West Matanzas and damaged. Damage repaired prior to Aug. 1, 1928. 27 Keystone S. & W. Co*_ Not flooded 28 Lacey-Langellier_ Lacey-Langellier Oct. 6, 1926 153' Prior to Sept. 1, 1928. Prior to Sept. 1, 1928. 415' 29 Liles Metz*.. Not known.._ 8 breaks from station 30 Liverpool_ Not flooded 3+39 to 63+00. Total length 636' Prior to Sept. 1, 1928. 31 Lost Creek_ .. Oct. 4, 1926_ At Chandlerville Roa d above 32 Lynchburg_ Oct., 1926 (?) original levee. 25+40 90' Prior to Sept. 1, 1928. Not filled July 29, 1927. Lynchburg_ Oct., 1926 (?)_ 83+79.5 179' 33 Oid Mauvaisterre_ Not known.. _ 7 breaks between sta- 34 Mauvaisterre_ Sept. (8 or 9), 1926 tion 15+07 and 54+25. South end between Total length 294' Partly filled Sept. 22,1927. station 2 and station 16. Previous to Sept. 20, 1927. 35 McGee Creek.. Sept. 5, 1926_ Flooded through Liles Metz and Cham- bersburg districts. 6+00 South McGee Creek_ Oct. 7, 1926.. 200' Breaks repaired previous previous to Sept. 14, 1927; levee not to full grade and section. Previous to March, 1927. Broke again and re¬ paired prior to Oct. 1, 1928. Prior to May 1, 1928. 36 Meredosia Lake. ... Oct. 7, 1926_ 258+00 Numerous 63' 37 A. J. Metz__ 38 Naples City_ . Sept. 8, 1926 Through Mauvaisterr e District 39 Nutwood_ . Not flooded 40 Partridge__ Abandoned. 41 Pekin and LaMarsh. Sept. 1, 1926_ 231+81 443' Previous to Feb. 7, 1928. Commissioners report. 1926. Pekin and LaMarsh 150' Pekin and LaMarsh. 60' 42 Robley__ Flooded around n ortheast end of levee 43 Rocky Ford_ Not flooded_ 44 Schaeffer... . . 1926_ 49+60 Previous to Oct. 19, 1927. 45 Schulte__ 1926_ 46 Scott Co.. Sept. 9, 1926 . Northeast end Previous to Sept. 20, 1927. 47 Seahorn..... Not flooded.. 48 South Beardstown.. Not flooded... . 49 Spankey__ Not flooded 50 Spring Lake_... Not flooded.. 51 Spring Run_ . Not known Opposite Coon Run station 157+75. 52 Thompson Lake_ Not flooded__ 250' Previous to Sept. 23, 1927. 56 FLOOD CONTROL REPORT. TABLE NO. 5—Concluded. LEVEE BREAKS—1926- No. District. Date of break. Station. Length. Date repaired. 53 Tuscarora.. _ Not flooded_ 54 Valley... Not flooded__ 55 Valley City___ Sept. 8, 1926_ 9 breaks north end be- 56 West Matanzas_ Oct. 7, 1926_ tween station 1+15 and 16+72. 180+60.5 Total 793' 263' Prior to May 1, 1928. Prior to Aug. 1, 1928. 57 Wilson Ranch_ Not flooded_ 58 Wolf Creek_ Sept. 8, 1926- 13+40 South end 39+00 to 60+00. 45' 59 Youngs_ Not known.. . .. 7 breaks, Total 145' not all filled. Previous to Oct. 14, 1927. * Several small districts, nearly all private, have been included in Table No. 5, which were not in¬ cluded in Tables Nos. 1 to 4. . From 1884 to 1900 the average amount of water carried by the Illinois-Michigan Canal from the Chicago River to the DesPlaines River was about 600 cubic feet per second. The Act of the Illinois Legislature providing for the construction of the Chicago Sanitary and Ship Canal required that 20,000 cubic feet per minute for each 100,000 population in the Sanitary District of Chicago should be diverted from Lake Michigan to the DesPlaines and Illinois Rivers. The Federal govern¬ ment, thru the War Department, issued permits from time to time for the diversion from Lake Michigan for such amounts of water as would not interfere with navigation in the Chicago River. The increase in the stages of the Illinois River, due to diversion from Lake Michigan, may be determined by considering that the normal flow of the river is increased by the amount of the diversion from Lake Michigan, and is represented by the difference between the observed stage and the stage corresponding to a discharge rate without the diver¬ sion. The average daily flow thru the Chicago Sanitary and Ship Canal for each month since it was opened in 1900 is shown in the following Table, No. 6. ILLINOIS RIVER. 57 TABLE NO. 6—SANITARY DISTRICT OF CHICAGO—MAIN CHANNEL—MEAN MONTHLY AND YEARLY DISCHARGE AT LOCKPORT. Year. % Jan. Feb. Mar. Apr. May. June. July. Aug. Sept. Oct. Nov. Dec. Mean. 1900. 1,449 2,315 2,099 2,727 3,228 3,226 3,353 3,576 2,307 3,450 3,813 4.334 2,990 1901.. 4,917 5,078 5,349 4,371 3,106 2,903 3,139 3,932 3,906 3,841 3,896 4,114 4,046 1902.. 4,194 4,204 4,233 4,165 4,166 4,071 4,323 4,204 4,291 4,155 4,248 5,352 4,302 1903.. 6,124 5,749 5,261 4,638 4,569 4,812 4,870 4,533 4,331 4,545 4,686 5,538 4,971 1904.. 5,457 5,170 5,549 5,311 5,125 4,101 4,553 4,573 4,151 4,004 4,452 5,067 4,793 1905. 5,167 5,527 5,546 4,737 4,066 4,153 4,122 4,291 4,341 4,510 3,378 3,919 4,480 1906. 4,457 4,626 4,393 4,568 4,719 4,420 3,996 3,426 3,740 5,221 5,198 4,907 4,473 1907_ 5,304 5,467 4,954 4,959 5,032 5,522 5,597 6,249 4,703 4,205 4,395 5,005 5,116 1908.. 4 4,057 4,462 6,781 7,660 7,529 7,466 6,861 6,704 6,533 6,506 6,371 6,389 6,443 1909.. 5 6,154 6,117 6,090 6,704 6,813 6,886 7,133 7,014 6,587 6,197 6,072 6.178 6,495 1910_ 6 6,830 6,459 7,055 6,964 6,968 7,219 6,870 6,677 6,572 7,061 6,800 6,523 6,833 1911. 7 6,128 6,113 5,943 6,072 6,246 7,154 7,646 7,354 7,578 7,902 7,611 7,001 6,896 1912... 8 6,239 5,968 6,135 6,829 6,344 6,871 7,500 7,766 7,764 7,619 7,411 6,809 6,939 1913_ 9 6,822 6,629 6,487 6,768 7,874 8,372 8,567 9,156 9,151 8,662 7,957 7,635 7,839 1914_ 10 7,319 7,312 6,858 7,205 8,027 8,168 7,863 8,252 9,060 8,392 7,624 7,703 7,815 1915.. 11 7,451 7,661 7,344 6,809 7,587 7,875 7,772 8,470 8,085 7,748 7,986 8,064 7,738 1916... 12 7,926 7,601 7,572 7,491 7,759 8,506 9,569 9,065 8,163 7,972 8,434 8,345 8,200 1917.. 12 8,147 7,850 7,746 7,883 8,109 9,190 9,976 9,876 9,703 9,107 8,758 8,361 8,726 1918_ 13 7,721 8,492 8,354 8,604 8,962 9,486 9,928 9,348 8,668 8,722 8,726 8,910 8,826 1919_ 13 8,537 8,023 8,563 8,780 9,754 9,006 8,586 8,486 8,225 8,615 8,675 7,882 8,595 1920... 14 8,178 8,114 8,528 8,246 7,776 8,046 8,219 8,502 9,061 8,753 8,472 8,258 8,346 1921.... 14 7,818 7,795 7,798 8,051 7,771 8,132 8,924 8,581 8,596 8,876 9,121 8,757 8,355 1922... 15 8,418 8,328 9,014 8,563 9,226 9,321 9,431 8,968 9,137 8,822 8,808 8,228 8,858 1923_ 15 8,126 7,761 8,011 7,953 8,328 8,448 8,402 8,756 8,749 8,677 8,545 8,374 8,348 1924_ 15 7,708 8,369 9,829 10,050 9,929 10,820 10,073 10,598 9,786 9,462 8,717 8,208 9,465 1925_ 15 7,737 8,003 8,348 8,641 8,608 8,763 8,768 8,493 8,612 8,281 7,526 7,547 8,278 1926... 12 7,189 7,744 7,960 8,846 8,605 9,145 8,871 8,955 7,828 6,745 8,815 8,690 8,283 1927.... 12 8,520 7,870 9,110 7,855 6,790 6,555 7,835 9,115 10,045 9,795 10,245 7,675 8,450 1928. 12 8,455 1929. 1930_ O* I bO t-. O > < o> O bD c3 f- > < lO 0) Sf 0) > < 1908 to 1925 inclusive—discharge=(turbine flow from rating tables 1912+615CFS+dams and sluice gates flow) 1.00+ per cent. 1926 to date. Percentage added only to turbine flow. Note. —All discharges are expressed in cubic feet per second. The diversion authorized by Federal Permit of March 5, 1925 is an annual average of 8,500 cubic feet per second plus the City of Chicago pump- age, which averages approximately 1,500 cubic feet per second, giving an authorized discharge of 10,000 cubic feet per second. Since the issuance of the permit the discharge has been under the control of the U. S. District Engineer. By his order, at times of flood in the Illinois and Mississippi Rivers, the flow has been reduced below the permit authorization. EFFECT OF LEVEES ON FLOOD STAGES. The practical effect of building levees on the Illinois Eiver has been to increase the stages and prolong the duration of high water. The fall or slope has been so modified from LaSalle to Hardin that during the critical period, when the flood wave is passing, the carrying capacity of the river channel at any stage is less than before the levees were built and even at the maximum stages which have been attained since levees were constructed, the carrying capacity of the channel is less than the carrying capacity at maximum stages before the levees were built. The changes in the flood-plain produced by construction of levees, and the increased flood stages between LaSalle and Grafton compared with 1904 are shown in the following Table No. 7. 58 FLOOD CONTROL REPORT. TABLE NO. 7—FLOOD-PLAIN AREAS AND INCREASE IN FLOOD STORAGE, 1904 TO 1926 Location. Area of flood-plain. Average increase flood stage. Storage Acre-feet Increase or decrease in storage 1904 to 1926, acre-feet. 1904 1926 1904. 1926. LaSalle to Peoria... 59,430 57,120 0.78 ft. 828,400 832,000 +3,600 Peoria to Havana_ 55,700 20,500 2.75 ft. 587,000 280,000 —307,000 Havana to Beardstown_ 60,600 54,580 4.98 ft. 582,800 635,000 +52,000 Beardstown to Valley City. 67,000 11,670 5.59 ft. 589,800 194,400 —394,900 Valley City to Pearl.... 40,400 5,860 3.68 ft. 296,000 74,600 —221,000 LITIGATION. The State of Wisconsin some years ago brought snit in the United States Court to enjoin the Sanitary District of Chicago and the State of Illinois from diverting water from Lake Michigan. Other states border¬ ing the G-reat Lakes joined in the suit. A decision was recently handed down by the Supreme Court of the United States finding that the Sani¬ tary District of Chicago has no right to divert water for sanitary pur¬ poses, but that the United States Government has the right to use water necessary for navigation. A determination of the time and conditions under which the decision can be enforced is now pending under orders of the United States Supreme Court. An Act under which the Sanitary District of Chicago was created provides that the owners of land that may be overflowed by the increased stages of the river, produced by the diversion of water from Lake Michigan, may recover damages from the Sanitary District of Chicago. Owners of land in the Illinois Valley have been negotiating and litigating with the Sanitary District of Chicago to recover damages for overflow during almost the entire period since the flow began, and there are now pending before the courts and before the Special Commission, authorized by the Fifty-fifth General Assembly of Illinois, claims in excess of $10,000,000. Prosecution and defense of these claims have created among the people thruout the valley intense feeling and suspicion against the Sanitary District of Chicago, which is a drawback to the development of the valley. Notwithstanding that the Deep Waterway from the Lakes to the Gulf requires a diversion of water to maintain navigation, the people who own the lands are less interested in deep waterways than they are in the preservation of their property, and many oppose the Deep Waterway Project because of their feeling against the Sanitary District of Chicago. INVESTMENT VALUES. The importance as a community value of the land in the levee dis¬ tricts of the Illinois Valley is indicated by the summation from the Tables of Statistical Data. These statistics were obtained, in part, from the records at the county seats of the counties in which the districts are located, and from owners and district officers. From the summation of Statistical Data, Table No. 8, it will be observed that the organized levee districts cover 201,194 acres, more than one-half of the valley area. There remain 71,000 acres available for leveeing. It will also be ob- ILLINOIS RIVER. 59 served that there are 4,295 persons residing in the districts and 1,810 persons employed in, but residing outside the district. It will also be observed that the average value of the land is $105.00 per acre, with a total valuation of $22,176,000.00. The Alvord and Burdick report showed $112.00 per acre as the average value of the leveed land in 1914. It will also be noted that the average cost of reclaiming the land has been $63.50 per acre, and the present outstanding bonded indebtedness is an average of $26.50 per acre.* The estimated market value of the farm crops on these leveed lands is over $6,500,000.00, or an average of about $35.00 per acre, estimating 80 per cent of the cultivated area in corn, 15 per cent in wheat and 5 per cent in oats, using as average market prices per bushel, 75 cents for corn, $1.00 for wheat and 40 cents for oats. The estimated market value of the crops produced is slightly more than $1,000 per capita, resident and non-resident, employed on this land. TABLE NO. 8.—SUMMATION STATISTICAL DATA- ILLINOIS RIVER VALLEY. -LEVEE DISTRICTS IN Total area in Districts. Assessable . Cultivated . Levees . Open ditches. Tile ditches-mains. Highways graded . Highways graveled. Highways paved . Railroads. Dwellings . Resident population . Non-resident employed . Corn produced per acre. Wheat produced per acre. Oats produced per acre. Hay produced per acre. Value of land per acre. Total farm improvement. Farm improvements. Total farm values. Damages to farm improvements 1926-27 floods. . Cost repairs to levees and ditches since 1922 flood. Assessments total . Assessments paid cash. Bonds issued . Bonds outstanding . Cost per acre (average). Bonds per acre (average) issued. Bonds per acre (maximum) issued. Bonds per acre (outstanding). $ 201,194 188,873 183,519 332 376 267 241 1.5 19.85 41 1,043 4,295 1,810 52 52 40 2 105.00 2,500,000.00 12.00 22,176,000.00 336,330.00 3,095,000.00 11,809,000.00 3,098,000.00 9,044,000.00 4,977,000.00 63.50 49.50 168.00 26.50 acres acres acres miles miles miles miles miles miles miles persons persons bu. average bu. average bu. average tons average average per acre average Note. —All statistics were obtained from statements of land owners and officers of levee districts and are approximately correct. RAINFALL AND RIVER STAGES. Any discussion or study of floods, without taking into consideration the rainfall, would seem to be inadequate and inconclusive. The daily rainfall records published by the U. S. Weather Bureau, for rainfall stations maintained on or adjacent to the watershed of the Illinois River, are the sources of information for this report. There are many varying * Note by the Division of Waterways. It should be noted that an average of $14.00 per acre has been paid by owners in cash and represents in most cases an unpaid mortgage on their property so that the actual unpaid cost of reclaiming the land is probably nearer $36.00 per acre. Also it might be mentioned that much of the land in these Drainage and Levee Districts has had to be mortgaged to pay interest and to carry on farming opera¬ tions largely because of crop losses during flood years. 60 FLOOD CONTROL RETORT. elements of climate, season, soil and topography which affect the ratio of rainfall reaching the streams as flood run-off. These variables cannot be definitely allocated and can only be taken into account upon the laws of experience and averages. The rainfall records from the Illinois River watershed cover a period of 71 years, from 1856 to 1927. The rainfall of any storm varies greatly at different points. Fre¬ quently there are local showers that cover only relatively small areas, so that the rainfall record of any one station is not representative of the entire area of the watershed. Rain gauging stations are not equally dis¬ tributed over the watershed and the arithmetical average of the daily rainfall does not give the correct volume of rainfall. To obtain the nearest practicable volume of rainfall a “weighted average” was ob¬ tained. The daily recorded rainfall at each gauging station was mul¬ tiplied by a factor representing the ratio of the area assigned to each gauge to the area of the watershed. The area of each gauge was determined by extending half way to the next gauge station. hydro¬ graph of river stages was platted for each tributary and for a number of points along the Illinois River, together with the weighted average rainfall to graphically show the relation between rainfall and the river stages. See Figures A 10 to A 36 Appendix A. Detailed studies of the amount of rainfall and the amount of rise, due to that rainfall, are discussed and shown in Tables A 1-A 10 Appen¬ dix A. The number of flood crests studied and the maximum, mimimum and average rise per inch of rainfall are shown in the following Table No. 9. TABLE NO. 9—RISES IN FEET PRODUCED BY ONE INCH OF RAINFALL. Station. Season. Floods of 1892, 1893, 1898, 1900, and 1904. Floods of 1913, 1915-16, 1922, and 1926-27. Num¬ ber of rises. Rise in feet per inch of rainfall. Num¬ ber of rises. Rise in feet per inch of rainfall. Maxi¬ mum. Mean. Mini¬ mum. Maxi¬ mum. Mean. Mini¬ mum. Morris Dec.-Apr_ __ 23 9.34 4.12 1.19 20 5.92 3.65 2.35 May-Nov_ 2 1.92 1.47 1.01 10 4.25 2.50 1.27 LaSalle_ __ Dec.-Apr_ 7 5.33 4.22 1.06 27 9.56 3.22 0.83 May-Nov_ _. 4 2.83 1.90 0.60 8 3.61 2.24 1.65 Peoria_ __ Dec.-Apr.. .. . 22 5.09 2.51 0.95 18 4.58 2.30 0.40 May-Nov_ 8 3.48 1.59 0.48 13 2.96 1.59 0.48 Havana_ Dec.-Apr_ . 13 3.86 2.15 0.59 10 3.46 1.85 0.99 May-Nov... ... 1 1.14 1.14 1.14 15 4.28 1.45 0.32 Beards town_ Dec.-Apr __ . 14 4.62 2.09 0.72 11 3.61 1.93 0.68 May-Nov... 10 3.95 1.12 0.33 15 4.00 1.74 0.42 STORM CENTERS AND RAINFALL. The storms which have produced the great floods on the Illinois River approach from the southwest. The rainfall on the Sangamon and other southern tributaries is frequently 50 to 100 per cent more than on the northern area. ILLINOIS RIVER. 61 Studies of storm travel and frequency by the Miami Conservancy District after the great storms of 1913 showed that the centers of greatest rainfall pass to the south of the Illinois River watershed with diminish¬ ing rainfall on each side. Occasional storms with heavy rainfall ap¬ proach from the west, but these do not cover so large an area nor pro¬ duce as much rainfall as those approaching from the southwest. The air from over the warm waters of the Gulf of Mexico, heavily ladened with moisture, flowing northeast and meeting the colder air currents from the north, produce the great rainstorms which traverse the Central Mis¬ sissippi Valley and the Illinois watershed is in the path of the northern margin of many of these storms. From all available data it seems im¬ probable that any of the greater storms will center over the Illinois River watershed and therefore that the rainfall of September, 1926, which produced the maximum stages on the Illinois will seldom if ever be exceeded. The rainfall in the first half of 1927 was also unpre¬ cedented in the records of the Illinois Valley and produced floods almost equal to th,at of 1926. The total rainfall at Peoria, June to November inclusive, 1926, was 37.94 inches; the normal of these months is 19.38 inches with an excess of 18.56 inches or nearly 100 per cent. The total rainfall February to July inclusive, 1927, was 32.14 inches; the normal is 19.43 inches with an excess of 12.71 inches or nearly 70 per cent. The last half of 1926 and first half of 1927 is the period of greatest rainfall and prolonged floods in the history of Illinois. It will be interesting to note here in detail the normal monthly rainfall for the Illinois watershed and that which occurred at Peoria in the last half of 1926 and first half of 1927, shown in Table No. 10 and No. 11. TABLE NO. 10—NORMAL MONTHLY RAINFALL, ILLINOIS RIVER WATERSHED. Jan. Feb. Mar. Apr. May. June. July. Aug. Sept. Oct. Nov. Dec. North of latitude of Pe- oria . _ _ _ 1.74 1.59 2.60 2.88 3.89 3.75 3.30 3.28 3.69 2.43 1.97 1.71 South of latitude of Pe- oria___ 2.14 1.89 3.16 3.46 4.07 3.94 3.34 3.40 3.65 2.48 2.34 2.15 Combined. . _ 1.94 1.74 2.88 3.18 3.98 3.84 3.32 3.34 3.67 2.45 1.93 2.16 TABLE NO. 11.—RAINFALL AT PEORIA FLOOD PERIOD 1926 AND 1927. 1 9 2 6. Month. Precipitation. June .. . 5.63 July . . 5.94 August . . 6.79 September . . 11.55 October . . 2.62 November . . 5.41 Totals. . 37.94 Normal. . 19.38 Excess . . 18.56 An. Normal. . 34.97 1 9 2 7. Month. Precipitation. February . . 2.85 March. . 4.55 April . . 4.87 May . . 9.22 June . . 5.71 July . . 4.94 Totals. . 32.14 Normal . . 19.43 Excess . . 12.71 An. Normal. . 34.97 62 FLOOD CONTROL REPORT. RAINFALL MAPS. Eainfall maps herewith. Figure Xo. 7, to Figure FTo. 16, inclusive, show the distribution of rainfall over the Illinois watershed that pro¬ duced the ten (10) floodcrests which have been especially studied, viz., April.. . 1927 October. 1926 April. . 1922 January . 1916 April. . 1913 April . 1904 March. 1900 March. 1898 March. 1893 Mav . 1892 The major floodcrests on the lower river occurred in 1904, 1922, 1926 and 1927. Each of these floods was the result of a succession of storms covering periods of from two weeks to 35 days, and the accumu¬ lated rainfall is shown by the isohyetal lines, or lines of equal rainfall. Each of these rainfall maps, except 1892, show the greater depth of rainfall on the southern portion of the watershed. The range in rain¬ fall for the various years was as follows: 1. 1927—From 14" at the south to 6" at the north end of the water¬ shed. 2. 1926—21" at Decatur and Beardstown in the southern and western portions and 7" in the northeast portion of the watershed. 3. 1922—17" in the southern portion and 4" in the northern portion of the watershed. 4. 1904—8" in the southern portion and 5" in the northern portion of the watershed. 5. 1916—9" in the southern portion and 4" in the northern portion of the watershed. 6. 1913—7" in the southern portion and 2" in the northern portion of the watershed. 7. 1900—5" in the southern portion and 2" in the northern portion of the watershed. 8. 1898—9" in the vicinity of Decatur, southern portion, and 4" in the northern portion of the watershed. 9. 1892—The storm was of a different character with a maximum rain¬ fall of 9" in the vicinity of Ottawa, 3" to 4" in the south¬ ern portion and 3" in the northern portion of the watershed. The flood stages generally progress normally down-stream from Morris to Beardstown, and from Beardstown to the mouth the crests are frequently in advance of the Beardstown crest, due to the in-flow of the tributaries and the earlier cresting of the Mississippi at Grafton. RAINFALL FREQUENCY AS RELATED TO FLOODS ON ILLINOIS. All great floods result from a succession of rainfall periods, which occur at intervals of usually about seven days with heavy precipitation for one to three days in each period. Spring and late winter rains produce greater flood stages relative to rainfall than summer rains, but the distribution duration and intensitv of the rain storms are the con- troling factors in flood run-off. Since a succession of rain periods cover¬ ing from two weeks to five weeks is necessary to produce a great flood, studies were made of the monthly and bimonthly rate of rainfall to be expected. These studies indicated that the distribution and intensity ILLINOIS RIVER. 63 are of equal or greater importance than the total rainfall and the results were not useful. SECTION II—HYDRAULICS. INTRODUCTORY. A thorough investigation of the hydraulics of the river was neces¬ sary for the study and solution of the problem involved in this report. Much of the basic data obtained in years past has become obsolete be¬ cause of the altered physical characteristics of the valley. The water now has a narrow passage through which to flow, con¬ sequently any volume will rise to higher levels in the efforts to get away. The storage conditions are modified and the retarding effects are changed. Where formerly a large part of the flow was through timbered areas, much of that portion is now diverted to the channel proper. This has the effect of changing the friction co-efficients which had to be re¬ determined. Considerable new data was furnished by observation on the floods of recent years by the U. S. Engineers, U. S. Geological Survey and the Sanitary District of Chicago, which increased the opportunity for hydraulic research. Although the conditions under which the measure¬ ment of flow must be made in flood periods cause apparent inconsistencies in the results, there has been accumulated such a quantity of material that by comparing and averaging measurements, deductions can be made, conclusions drawn from studies and forecasts made as to the probable future flood heights to be attained with a greater degree of certainty than has been heretofore possible. U. S. ENGINEERS SURVEYS OF 1902-1905. The surveys of the valley by the U. S. Engineer Department from 1902 to 1905 (House Document 263, Fifty-ninth Congress, First Ses¬ sion) was thorough and made in such detail that it has supplied much of the basic data for hydraulic investigations. A major portion of the territory surveyed between LaSalle and Grafton and over the width of the valley has changed more in appearance than in contour. By the construction of levees land has been reclaimed, swamps and timbered areas have been converted into cultivated fields, but the cross section of the valley for practical purposes has been altered only by the filling in or scouring of the river bed, which is a very small portion of the valley section. Surveys have been made within the past few months by the U. S. Engineers to determine the change in regimen of the river channel, but soundings were not reduced until recently so that only a part of the data obtained was available for use in this report. The changes that have taken place are known to be so small that flood flow areas here used are not materially affected. VALLEY SECTIONS AND STORAGE AREAS. Cross-sections of the Illinois River Valley between Starved Rock and Grafton were platted from the topography sheets of the U. S. Engineers 14-foot Waterway Survey at 149 places, at intervals of from 64 FLOOD CONTROL REPORT. 1,900 to 20,200 feet, and combined into 49 “reaches,” ranging in length from 5,000 to 40,000 feet. The levees were located on these maps by the Engineers of the Sanitary District of Chicago. The locations for the cross-sections were chosen and combined into reaches (see Table No. B 1 Appendix B) without great variation in cross-section, as controlled by levees on one side of the channel or on both sides of the channel, etc. The areas of the overflow sections, exclusive of the channel, were determined from the platted cross-sections (see Figure No. 17). The areas of the channel section for each reach were determined by add¬ ing to the average area below the 1901 low water for each reach, the area above the low water for the reach, determined by multiplying the average width of the channel by the depth above the elevation of the 1901 low water. The area of the channel section was determined from cross- sections and tabulated areas at intervals of about 200 to 500 feet, fur¬ nished by the IT. S. Engineer’s Office at Peoria. %j o Table No. B 2, Appendix B shows: 1. The station in miles and in 1,000 feet above Grafton of the begin¬ ning and end of each reach. 2. The elevation of the 1901 low water at the centers of reaches. 3. The average width of the channel through the reach at the elevation of the 1901 low water. 4. The average area of the channel through the reach below the eleva¬ tion of the 1901 low water. 5. The length of the reach in feet. 6. The width of the over-bank section, exclusive of the channel, for each foot of depth above bank-full stage. 7. The area of the over-bank section, exclusive of the channel, for each foot of depth above bank-full stage. 8. The areas of the channel for each foot depth above bank-full to high water, including area below bank-full stage. 9. The combined area of the over-banks and channel sections for each foot of depth above bank-full to high water. Storage in the Illinois Kiver Valley above bank-full stage was pre¬ pared by adding the cross-section areas of the over-banks section, shown in Table No. B 2, in Appendix B, the channel storage above the low water stage and reducing to acre-feet. Table of Storage, No. B 3, Appendix B, shows: 1. The station numbers (1,000-foot stations) above Grafton for the beginning and end of each reach. 2. The length of each reach in feet. 3. The increase in storage for each foot in elevation from bank-full stage to high water for the elevation of the center of the reach. 4. Total storage for each foot of elevation at the center of the reach above bank-full stage. Figure No. 17 indicates the method of combining the end areas to obtain river floodwav storage. Storage is also shown on diagrams, Figure No. B 1 to Figure No. B 10, Appendix B. Figure No. 18 is a diagram for scaling the storage above the bottom land in five reaches, from lower end of Nutwood Levee District to LaSalle. ILLINOIS RIVER. 65 STAGE RECORDS. In the Alvord and Burdick “Report on the Illinois River and its Bottom Lands” there is published a list of gages in the Illinois and Des- Plaines Rivers up to 1914. Most of these gages are still maintained, but others have been installed in recent years and the elevations of many have been changed. Table No. 12 is a list of the present gages of the Illinois River and tributaries, as compiled by the engineers of the Sanitary District of Chicago, giving the stations, authorities and elevations of gages where readings were taken along the river between LaSalle and Grafton, and used in the studies of this report. TABLE NO. 12—STATIONS AND ELEVATIONS OF GAGES, ILLINOIS RIVER. Station. Miles above Grafton. Sanitary District of Chicago. U. S. Engineers. U.S. G.S. U. S. Weather Bureau. (1928) Eleva¬ tion of zero, Mem¬ phis datum. 0 Grafton_ __ . 410.99 165+792 31.4 Kampsville (lower)_ 409.10 166+320 31.5 Kampsville (upper).... 409.13 227+750 43.2 Pearl__ 419.70 325+250 375+250 61.6 Valley City_ 421.75 71.1 Meredosia_ 424.22 409+200 77.5 LaGrange (lower)_ 418.23 409+750 77.6 LaGrange (upper)_ 418.23 469+100 88.8 Beardstown (C. B. & Q. R. R. bridge)_ Beardstown High¬ way bridge_ 427.25 512+500 97.2 Browning__ 433.35 589+776 111.7 Bath.__ 433.46 633+300 119.9 Havana_ 431.93 676+000 128.0 Liverpool_ 440.30 721+776 136.7 Copperas Creek (lower) Copperas Creek (upper) 427.75 722+300 136.8 432.73 766+765 145.6 Kingston Mines. 439.73 807+350 152.9 Pekin_ 438.57 847+968 160.6 Peoria (P.&P.U. bridge) 856+750 162.3 Peoria (lower wagon bridge)_ 435.82 866+448 164.1 Peoria (U. S. boat yard) 960+300 181.9 Chillicothe_ 436.32 998+700 189.1 Lacon_ 442.99 1,034+880 196.0 Henry (lower)_ 436.64 1,035+408 196.1 Henry (upper)__ 443.79 1,095+072 207.6 Hennepin _ _ 442.60 1,185+600 224.5 LaSalle Highway 444.13 High water stages of the Illinois River between Grafton and La¬ Salle are recorded in House Document 263, Fifty-ninth Congress, First Session, pages 193 to 206, with description of the high water marks and the authorities for the information. The following Table, No. 13, gives the revised high water data from 1879 to 1927, inclusive, for the Illinois River from Grafton to Morris. This data is taken from House Document 263, Fifty-ninth Congress, First Session, for the period from 1879 to 1904, inclusive, and subsequently from the gage records of the U. S. Weather Bureau, U. S. Engineers and the Sanitary District of Chicago. 5 F C TABLE NO. 13-ANNUAL HIGH WATER DATA AND ELEVATION-ILLINOIS RIVER. 66 FLOOD CONTROL REPORT. cm C5 d * > g © o tt 3 05 to CO CM O 00 o **p to CM O O CM CO CO CO Tp Tp «*P CO CO 05 to o oo OSO’- COrf rf Tp Tp tP CO CO CO O N- 05 05 CO COCO»ON Tp Tp Tp tp TP Tp Tp TP 00 CO CO CM CM CO to CO i—• Tp OO 05 05 *—> CO TP Tp Tp to to CM 05 TP 05 to to NNihNCO CO o CO CC CC Tp -

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ILLINOIS RIVER 67 05 05 i • i r>- till 40 1 1 1 co 1 1 1 1 03 1 1 1 till 1 CO g -• 40 03 i i i oo till CO 1 1 1 N- l l 1 1 03 1 1 1 till CO 05 1 1 1 05 1 l 1 l O 1 1 1 Tt< 1 1 1 1 i—1 1 1 1 1 1 1 1 ' 40 N OO o> o 03 ^h i i i 03 1111 1 1 1 «rfl 1 1 1 1 40 1 1 1 1 1 1 1 14000 p' 3 hF hF i • i 1 i i till 1111 1 1 1 1 1 Tf 1 1 1 1 1 1 1 -rfi 1 1 1 1 1 1 1 1 till 1 1 1 1 1 Hfl Tf ^ 1 TF i i i 1111 1 1 1 1 l l 1 1 1 1 till 1 ^H n- oo i i 1 OO 1 1 1 1 CO 1 1 « 40 1 1 1 1 03 1 1 1 1 1 1 1 ' CO CO CO 05 03 i-H 1 1 1 1—( 1 1 1 1 1—1 1 1 1 1—1 1 l 1 1 f—i 1 1 1 1 1 1 1 1 l-H ^H 1 1 1 l 1 1 1 1 o 1 1 1 lilt 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 -*-* c 3 1 l 1 1 1 1 l 1 1 1 1 1 1 1 1 l . 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"© © > o XI l l 1 i 1 l I 1 i i i i > © ! a > < ^ o : 1 1 1 1 1 1 • fcfl • I p • i i i i i i i i ;G>r '. © P M 5 P CO d* p < » 4 CQ ! >> i IO i . i i .5 *c n O ^ « a © © & Wi M O c p +* . ! M <3 C C 1-5 © : : :o ! 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T-H 1 t-H 1 T-H t-h CM CM CM CM CM CM i i i i i i i i i i « CM CM l i i 1 T-H 1 rH 1 i 1 T-H T-H 1 i i i i >> 1 ! >. >» >> d d d d d d U u i i i i i i i i i i i i i i i i l (h U i i i 1 1 t- d i i i 1 1 tH tH i i i i t i 1 1 1 d • a d §§ d 03 o3 c3 d • i i • i i c3 c3 i i d d i ' o3 aS i i 1 1 1 c3 S !S S i i i i i i i i i i i i :s § i i :§§ i i i i 1 I i »eH i t 1 A cO i i O CO o OO CM OO OO i i i i i i i i i i i i i • to CO i i i i CM CM i i i 1 Tf co i i i i i l i l 1 to CO i i—i CO CO O -rf o o i i i i i i 1 00 T-h i ! 00 CO i ' O CO i i l l l o as o to i oo co to oo i i i i i i 1 kO CO i i o o i 1 CM CM i i • i 1 CM *n CO i • o oo 0^0 05 OO CO i ■ i i i i i i • » t>» i • to co i i i • CM i i i l Tf CO i i i i • i i to to o ! NNtOOOOCO i i i i • CM • 00 T-H i i to i 1 05 o i i 1 1 ' OO CO 03 O 05 • 05 05 ONCOtONOO i i i i 1 TJ1 l to co i • o 05 i 1 O T-H i i 1 1 1 T-H Tf CM > CM CM CM CM CO CO CO CO i i i i 1 • ^ Tt< i 1 kO **f i • to to i i 1 1 1 05 05 Tf 1 T}1 Tt< Tf rf< rti rj* -rf i i i i 1 Hf 1 Hf TJH i 1 Tf Tf i 1 Tf Tf i i 1 1 1 Tf Tf CO 1 i t i 1 1 1 05 o • o O t-h CM CM CO CO CO i i i i • CM 1 T-H T-H i 1 T-H T-H i 1 T-H t-H i i 1 1 1 TH OO T-H d CO 1 CO 1 CO CO i i i i i i i i i i 1 i i 1 1 i 1 1 1 i i i i III CM 1 1 1 c3 >i - Q >> 1 >J & a c c c c i i i i ! d ! a a i ! d d i ! d d i i : : : d-g s g S 1-3 o3 c^ 03 d i i i i i c3 i d d i 1 c3 d l i d c3 i i . . i.03 r P ck • > g CO CO' • o CO CO to to oo CO i i i i 1 t'— l l co i • CM i ' Tf CO i i 1 1 1 to to T-H to 1 CO 00 o NlOrHCO i i i i i i i i • CO • 1 to i i 1 t-H T-H i i ' oo i i i i 1 i 1 O l-» a) o Tf CO • CO CO 00 O CM CO CO i i i i • 1 1 05 i 1 Tf Tf i I to to i i 1 1 1 OO T-H CO CO i CO CO CO 'Tf Hf ^ i i i i i ■ '?■ 1 1 1 i i i i i i i i i i i i • CM i i 1 1 CM 1 1 1 1 1 1 i i i i ' CM i i i CM i 1 1 1 ' CM CM i i i i i i i i i i II 1 CM l i i i l l d n ^5 d • d d d d d d d i i i i i i i i i t- 1 1 S-H i i l u d i 1 i d d i i i i ' ! I OS g <3 o, ■ a ft ft i i i i i <3 • i c3 i ' d d i • d d i i l I iH w l i \< i i i i : s : :§ i i i t i c3 • > a to to i 1 to OO CO t-H CM CO OO to i i i i i i i 1 fT- i i • 1 CO i i i i CM i i i 1 Tf co i i i t ill i ill i 05 CO I CO to o CM CM O t-h ^H i i i i i i i cO 1 1 05 i i ! CM i i • OO 05 i i i i ill l iii i (D O GO Tf • to to oo T-H -Tf to to rd i i i 1 05 1 i o i • to to i 1 CO co i i ill l CM CM • CO CO CO •*r *rr Hf i i i • ''et« i i to i i to to i • to to i i ill i Tf Tf i rfl Tt« ^ ^ Tf i i i 1 TJH 1 1 Tf i • Tf Tf 1 1 Tf Tf i i ill 1 CD 05 CO i N CO ^ co co T-H i i i • CM i 1 CM i 1 T-H T—H i 1 o o i i ill i rH d CM i i i i i i i i i i i i i i i 1 1 1 1 1 1 i i i 1 CO 1 1 CO i 1 i 1 CO CO 1 1 i i i i i i ill i III i ill i o3 ^5 d . i i i i 1 i 1 . i i ill i n c3 q, • d d u* d In d d d i i i • d i 1 d i 1 t- tH i 1 tH tH i i ill l Es ■ a ft ft Ch ^ Ch M a i i i 1 a ! ! 0. i • d c3 i i d d i i III i !< a to 1 O 00 CO o O CM CO 00 to i i i 1 t-. I>- l to co i i CM CM i 1 Tf CO i i ill i T-H • CO 05 CM CM tONCDC5 CO i i i i i i I OO CO 1 to L'- i i I 05 TH kO l i • O CM i i i i ill i ill i oi o 05 1 o O O CM CO 00 05 05 T-H i i i • Tt« to 1 CO CO i • O T-H O i • CM CM i i ill l M J CM 1 CO CO CO CO CO CO CO CO i i i 1 'Tf ^ 1 th T-ti i 1 kO to to i • to to i t ill i Tf iTPTfTjl Ttl -rj< TTti i i i 1 Tt< TJH • Tf Tf i • Tf Tf Tf l 1 Tf Tf i i ill 1 05 05 to i r— 05 to to to to ^ Tt« i i i i Tt< CM i CM CM i • CM CM CM i 1 CO CO i i ill i r-H d -M CM i CM CM CM i CM CM T-H r-H t-H tH i i i i i i i t-h CM i i CM CM i i i i CM CM i i i 1 1 i i i i ill i ill l i i i i i i i i i 1 i i ill i <3 i i i i d d i • i i tH tH i 1 . i i ill 1 Q >> u u u u *- d i i i i d c3 1 tH Sh i 1 tH 03 c3 i 1 t- tH i i ill l d g i d d g d w C3 o3 d ssss g i i i i i i • d d :§§ i i • a3 ;g ss i i 1 c3 c3 i i i i ill i ill l i i i i i i i ■ i • i i i i i 1 1 1 1 1 i i i i i 1 I t 1 1 1 1 1 1 1 1 1 till 1 1 1 1 1 1 1 1 1 i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i • i i i • i i i • • i i i i i i i i i i i • 1 1 1 1 1 i i i i i i ; i i i i l l i i i i i i i i i i i i i i i i i ill 1 ill l III l III l III l i • i 1 1 i 1 1 1 1 1 i i i i i o O ! o o i i i 1 i i i i i i III i 1 ) ■ H ' * i ,at; i 1 1 1 1 1 i i i i i i i i i i t l i i ill i i i o x> i i i i ! ! > o • • S > ! 1*2 o 1 1 1 1 i i i i i i • bJD • ! 63 • i i i i i i i i 1X2 as ! a> as i i m (D TJ ‘C X3 i i i i 1 O O i i i i i i i t 1 '‘tH 1 : C ' 1 £> d ! OjD 1 1 T^-J = ! fir i i i i 1 t-. t- :oog i CD ! £ ^ >> £3 GO GO £ a a Ha a w oj O tH d a ffi 73 CQ CQ 65»«— o tr ir b£.~. t_ ft ft p o .£ o o-~ o « ^OOWClhCl, •ft c3.~ ft >.>!»« t. H C P o £ a „ „ „ _ 0 c G c 01 2 o5o5 OhJWWWQPhg-Jg-3 Vi ^D ^ Cj ci d - m o t-h CM CO Tf to CONOOOS O to ONOOOJOrH CM t-h t-h t-h t-h CM CM CM «TfW30N00 050iH CM CMCMCMCMCMCMCMCOCO CO TABLE NO. 13—Continued. ILLINOIS RIVER. • > 71 CO *-H 1 1 • 00 W5 t'T. oo • W5 i i i i i 1 o OO 1 1 CM i l i -f CO i 1 i i i i i s 05 CO 1 1 ' co CO O T-H 1 CO 1 1 1 1 1 1 t>» oo 1 1 ^H i i i rfi ^ i 1 i i i i i 1 1 .ft-O ! P 1 1 1 l I 1 Q 33 1 1 P l l •33p i 1 i i i i i cd (D o o G t-H WO 1 1 t''- l ' WO O I OO 1 wo 1 l l l 1 l i i i i i i o oo 1 1 1 1 CM i i i i i i tF CO i i 1 1 i i i i i i i i i i CO t-H 1 Tt 4 • ^t 4 co CO 1 i i i i i i o CM 1 1 CO i i i CO wo i 1 i i i i i a> o Tt 4 CM • wo ■ 05 T-H CM 1 CO 1 1 1 1 1 1 05 o 1 1 i i 1 i 1 i i i i i h'- 5 CM CM 1 CO 1 CO CO ^ 1 1 ’ 1 1 1 1 1 TfH wo 1 1 wo i i i WO wo i 1 i i i i i ^ rji 1 Hti 1 ^ ^ rf • 1 1 1 1 1 1 Tfl 1 1 i i 1 -rf 4 '*p i 1 i i i i i r^. OO CO OO • o 1 OO wo WO WO i WO I I i i i I CM Cl 1 1 05 i i i O O i 1 i i i i • ^H d -4-9 t-H CM 1 CO 1 1 1 CM i i CM CM CM i i i CM i i i i i i CM i i i l i i i i i i i i CM 1 1 1 1 1 1 t-H i i i i i i i CM CM i i i i i 1 1 1 i i i i i i i i i i i i i i i e3 p £>£> ! >> • o3 '33 JO PP : P i i i » i i n P 1 1 1 1 P i i i i ■PP i i 1 1 i i i i i i i i i i ' 1 ! ! I I ! o Q) o ! a> 05 !S !p pp i p iiiiai M-M p 1 1 i i .pp i 1 i i i i i i 03 d CO i t'- 1 OO WO 1 OO 1 wo i i l i l l wo CO 1 1 CM i i ' co i 1 i i i i i CO 1 rt< 'OOW^N 1 o 1 • l l I • l wo CO 1 1 05 l i 1 OO T-H i 1 i i i i i Q> O CO i N i WO wo 1 05 1 o i i I I i i co CO 1 1 05 i i i T-H CM i 1 i i i i i P- 3 CO • CM 1 CO CO CO i CO I 'TP l l I 1 1 1 1 1 i i i wo wo i 1 i i i i i HJH 1 T* 4 1 "Tf 1 1 1 1 1 1 1 1 1 Tt 4 i i 1 H* 4 -f 4 i 1 i i i i i CO OO o 1 o 1 O O wo I wo 1 wo ••»»•* CO CO 1 1 T-H i i 1 wo Tt 4 i 1 i i i i i t-H d CO ' CO 1 ' CO CO 1 1 1 1 1 l l i i i l l l l 1 i i 1 1 1 1 i i i i 1 1 i i 1 1 i i i i i i i i 1 1 1 1 l l l i i l 1 1 t i 1 i 1 i i i i i a Q >> 1 ^5 !.>>>-. i « C3 Q 1 d 1 d 1 1 1 1 1 1 P. d 1 1 1 1 d i i i i 1 d d i i 1 1 i i i i i i i i i i c3 1 C3 ' > 1 ft 1 a iiiiii O- ft 1 1 ft i i • ci d i 1 i i i i i § :s IS :< i HJ l l l l i 1 ^ Hj 1 1 1 1 <1 i i i i :ss i i 1 1 i i i i i i i i i i I d • > wo wo 1t^- i r>- wo O cO i WO wo' 1 1 1 1 1 1 LfO CO 1 1 Cl i i 1 Ht 4 CO i 1 i i i i i CO T-H i -rf ! 00 CO OO CM 1 t-H CM 1 1 1 1 1 1 05 o 1 1 OO i i ' CM wo i 1 i i i i i - iiiiii oo t ^ 1 1 WO i i 1 CO CM i 1 i i i i i d CO 1 1 I 1 1 1 CM 1 1 I i 1 1 CM iiiiii CM 1 1 1 1 CM i i i i i CM CM i i i 1 1 i i i i i i i i i i d Q May lune 1 ' CD ! g 1 ! >> _>> 1 >! >. 1 P* 3 3 3 iiiiii iiiiii o IIIIII g—T G 1 1 1 1 1 1 G i i i i i i i i G O O • CM 1 wo WO ^ T-H 1 WO 1 1 1 i i 1 wo WO CO 1 1 CM CM i i 1 T-t 4 CO i 1 i i i i i CO CM 1 CO 1 CO T-H 1 1 1 1 1 1 1 T-H OO O 1 1 00 T-H i i 1 05 T-H i 1 • i i i t i a> o WO 05 • t>- 1 05 CO » O 1 1 1 1 1 1 Hf< T-fH lO 1 1 OO 05 i i 1 O T-H i 1 i i i i i P^ CM t^ i CM 1 CM co CO CO 1 i i i i i i n n n 1 1 '*t< Tt< i i 1 wo WO i 1 i i i i i Tf ^ i ^ 1 Tf< 1 1 1 1 1 1 1 TfrjH rf 1 1 i i 1 Ht 4 -rf 4 i 1 i i i i i o 1 1 i i i i i 05 O CO 1 CO 1 05 t-H t-H 1 O i i i i i i o o o 1 1 o co i i . T-t 4 TV i 1 i i i i i t—H Date. CO T-H 1 T-H 1 1 T-H 1 CM CM CM • i CM i 1 1 i i 1 CM CM CM iiiiii 1 1 CM CM i i ' CM CM i 1 1 i i i i i o . S G c 3 1 1 1 ! d 1 1 1 1 d d i l i d d 1 d iiiiii • i * • • i h d • i i i i i i h n ^ 1 1 1 1 1 1 1 1 • OJ ft c 5 * 3 i i i i i i i i i i i a> a> ! G G i i i i 1 1 1 1 i i i i i i i i i i i i i i i i i i i i ►"0 »"0 i d 1 c 3 o 3 c 3 i c 3 IIIIII *“0 ^ 1 1 i i i G G i 1 i i i i i ' ^o • »-D ^o H | —5 1 *-o IIIIII *-—^- ' G WO i 1!>- i • WO wo Tf CO CO wo IIIIII i i i i i i wo CO 1 1 1 1 CM i i i i 1 I HJ 4 CO i i 1 1 i i i i i i i i i i 00 i 05 1 ^ wo coon O 1 1 i i i i CO wo 1 1 CO i i 1 CO o i 1 i i i i i

3 WO i i CM i • O WO CM OO OO WO iiiiii 1 1 1 1 1 I WO CO 1 i »o CM i i i i i 1 -rti CO i i 1 1 i i i i i i i i i i CO i CO 1 • i CM CO 05 HjH W5 CO i i i i i i wo 1 CO i i » CO ^t 4 i 1 i i i i i ® o CO 1 05 i O CM co-n-n WO T-H 1 CO i i 1 o o i 1 i i i i i p J CO 1 CO • ^ ^ ^ ' r V i i i i i i wo wo 1 wo wo i i i CO co i 1 i i i i i ' ^ Tfl Tfl 1 1 1 1 1 1 Tf 1 TTf i i 1 Tt 4 'TT i 1 i i i i i CM 1 i i i i i i i 05 OO « 05 1 05 OO GONI^ CO 1 1 1 1 1 1 t-H T-H 1 05 05 i i i i 1 i i i i i t-H d -4-9 T-H 1 T-H 1 1 1 T-H 1 1 T-H T—1 T-H T-H T-H IIIIII t-H IIIIII IIIIII T-H 1 1 1 i i i i i i l 1 l i i i 1 1 1 i i i i i i i i i i i i i i i d >>>>>. Q ; >> 1 >> >1 >> >, 1 >1 ; >. >> c3 • d i a c3 Cj Cj c3 c3 IIIIII 03 03 1 o 3 cS i i i c 3 c 3 i 1 i i i i i s :s IS s sss s IIIIII hH IIIIII s :s s i i i i :ss i i 1 1 i i i i i i i i i i 1 1 1 1 1 i i i i i i i i i i 1 1 1 1 • 1 1 1 1 1 1 1 1 1 1 i i i i i i i i i i i i i i i 1 1 1 1 1 IIIIII 1 IIIIII 1 IIIIII 1 1 1 1 1 M i i i i i i i i i i i i i i i i i i i l i i i i i i i i i i i i i i i i i i i i i i i i i 1 1 1 1 1 i i i i i i i i i i i i i i ■ i i i i i i i i t i ; i i ; ; ; « o • 1 o 1 1 • i * 1 i i i i i i > i i i i i i £r i i i i i i o •. 13 0) i i i • t • i 1 ■ i • i i • 1 1 1 o ; o O 1 O ' 1 1 1 ■ o « 1 o o 1 1 1 > o XI i i i i i i i i :.S o 1 1 1 1 !!!!!! 33 i bO i i i i v • 3 • ; ; : o a r* 0) i • i 1 c n « a> • 73 ! ’C \ -o ! 1 o o » o o i i i i 1 1 1 1 1 !‘ c 3 i i i i i i C 3 ' 1 OJD 13 o 1 p. ! 1 ‘i P !3«J O 1 ! d" « ! 1 >> ,£> cl 3 1 H -- 1 1 1 (H :cr : : :o 1- G -H 1 a JD .2 *d o o 1 \S O i 1 o bO O ci i i 1 1 G O 4 ^ »H c3 1 ’G *r • • > 1 C co & i ft ft ' tz is S —> o >> Hi as cj aj •s Wi u S e c *th ci c3 U. tH £ o 4-5 (ft 73 Sh c3 Browning. Sharps La Chandler\ Bath _ Havana-. Liverpool. Copperas 1 § C ; 2 O <13 4-5 * O «J G g 4 hf-G ft^j G -*-5 „ O B g.g ’d n i cj 33 ' 33 cj 1 3 ^ ^ 3 tn t. 8 ? ? 3 ft a> 3 3 • 1 1 a> G ft £ •h G c3 dCEGO i i • i i i i i CO 1 ’£.p (h O CG C3 ffip PP Pj > ci ci o « O •— 01 GPP a> Ph ®-3 a> ci c3 pgPhCKWQpPP s^ ^H CM CO Tt 4 WO cd oo 05 o H ci co -»t wo CO OO 05 o T—H CMCO"dwocdr^OOO>O^HCMCO ^H t-H t-H t-H t-H t-H t-H t-H T-H ^ CM CM CMCMCMCMCMCMCMCMCOCOCOCO TABLE NO. 13—Concluded. 72 FLOOD CONTROL REPORT. i i—( t^. i O lO Cl 1 i »o 1 05 i 1 05 lO OO 1 1 1 i i i CO i i i i i i i « rt * 1 CO »o 1 CO O t>- • • 05 • OO i i 1 o CO CO 1 1 1 1 l 1 i i i • i i CM i i i i i i i i -rf »C « OO CO lo • 1 OO » O i 1 CO Tf 1 1 1 i i i 05 05 i i i i i i i 4 ) o I CM CM l Cl CO CO • 1 CO i ^ i i -t< 'TV Tf 1 1 l i i i Tf Tf i i i i i i i w ^ l ^ 1 -ctt Tf -rf 1 i l 1 1 1 Tt< 1 i i 1 Ttl 1 Tf Tf 1 1 1 1 1 1 i i i i Tf Tf i i i i i i i 05 i l i 1 1 i 1 1 1 1 t i i i i i i i i i l lO i IlO rf Tf* i 1 1 T-H i 1 o oo OO 1 1 1 i i i Tf i i i i i i i oo • c 3 1 i # 1 1 1 i i i i i i i i i i Q • -* P i P P P • 1 p 1 p i 1 p p P 1 1 1 i i i P p i i i 1 i i i : a a ; a a a ; 1 a 1 a i 1 a a a 1 1 1 i i i d d i i i i i i i : < < i g i 1 1 1 O lO Cl 1 l i lO i 1 05 i i i • o CO 1 1 1 1 1 1 i i i i i • N OO i i i i i i i i i i i i i i O i CO I rf OO CO 1 1 CO 1 lO i i 1 05 CO Tf 1 1 1 1 1 1 i i i i i i Tf i>- 1 i i i i i 1 i i i 1 i i ai o o 1 OO • T-H lO OO 1 • o 1 Cl i 1 -TtH CO CO 1 1 1 i i i T-H T-H i i i l i i 1 —• *jr 5 CO l CM i CO CO CO 1 1 ^fl 1 -Tt< i 1 Tf Tf 1 l 1 i i i *o no i i i i i i i • rfi I Tt» l 1 1 Tf i 1 Tt< Tf Tf 1 • 1 i i i Tf Tf i i i i i 1 i o oo 05 • 05 IQ 5 P P • l 05 • N i 1 CO CO 1 1 1 i i i Tf Tf i i i i i 1 i oo • CM Cl i 1 T —1 1 T-H i 1 T-H T-H T-H l 1 1 i i i i i 1 i y—< 1 (D i i 1 1 i 1 i l 1 i i • i i i -p> i i 1 1 i 1 1 1 1 i i i i i i i i i i d Q >> ! >> ;>!>)>) ! ! >> ! >> i • ! >> >> >> 1 1 1 1 1 i i i >> >, i i i i i i i d cj 1 • d i d i • d d d 1 1 l i i i d d 1 i i i i i i d i d 1 s : : s :a i i § £ 1 1 1 1 1 1 i • i i i i £ £ 1 i i i l i i i 1 i i i i i d • > g CO 1 coo' 1 O * CM Cl' t 1 lo »o i i i i N o OO 1 1 1 • i i i co co' i i i i i i i OO • OO CM ICO 1 Cl CO i 1 Cl CO i i i i CO T-H T-H 1 1 1 • i i i Tf CO i i i i l i i 1 • • i i i 1 1 1 i i i i i i 1 i 1 i i > > ;. : >> p : • i i i i i i 1 1 1 1 1 1 1 i i i i i i i i p* 6 l 1 i i i i l i i i i i i 0 >5 i o 3 o i £>5 i d d i I P O i i i 1 p P p 1 1 1 i i i i cS 0 i i i i i 1 i d a :§z 1 d 1 PH VP 1 1 ^ 1 ^ 1 • d g oo • o 1 1 1 1 1 1 1 1 1 1 1 O lf 5 i i i i i i i i i i O^icTcO 1 1 1 1 1 1 i i i i i i 05 OO 1 i i i i i i i i i i i i i ic i Cl till 1 till 1 1 CO o i i i i i i i i i i Tf IO 1 1 1 1 • l i i i i i i CO 05 1 i i i 1 i i i i i i i - CO i i i i i CO T-H T-H 1 1 1 i i i no no i i i i i i i oo 1 1 1 1 1 i i i i i 1 1 i i i i 1 i »-H CD till 1 till 1 1 1 i i i i i i i i i i 1 i 1 1 1 1 i i i i i i l i i i i 1 1 i i i a -p d Q >. »—H ! >> 1 1 1 1 1 till 1 1 1 1 1 1 1 0 !a? a ! 3 3 i i i i i i i i i i i i i i • i i i S c 3 o 3 c 1 1 1 1 1 1 1 1 1 i i i i i i i i i P* P* 1 l 1 • i i i i i i i 1 i i i i i i i i i d ►■o ! d • >“5 till 1 till 1 1 i i • i i i i i i i *”5 *“5 d 1 1 1 1 1 1 i i i i i i £ £ l 1 i i i i i i 1 i i i i i d • > g o'w? i O III 1 III i CO 1 1 ‘O i i i i i i i i i i o oo 1 1 1 1 1 1 i i i i i i Tf CO i i i i i i i i i i i i i i CO o • Cl iii i o 1 o i i i i i i i i i i o Tf 1 1 1 1 1 1 • i i i i i Tf co 1 i i i i i i i i i i i i i CD O >rt< H • OO iii i 1 05 i i i i i ci Cl 1 1 1 i i i OO OO 1 l i i i i i M ,i5 CO CO i CO III 1 Tfl 1 ^ i i i i i *o no 1 1 1 i i i no no i i i i i i i T* 1 III 1 ^ 1 t i i i i Tf Tf 1 1 1 i i i Tf Tf 1 i i i i i i CO oo lO t-H 1 p III i iO i to i i i i i »o no l l 1 i i • co Tf i i i i i i i t-H CD - 1 1 1 ci oo T-H 'Tf no CO 1 1 1 1 1 1 CO 1 1 O T-H 1 1 1 OO 05 T-H T-H OO 05 1 1 i to 00 O O 1—1 CO 1 1 1 1 1 1 1 1 O T-H 1 1 i Cl d CO CO Cl T-H 1 1 • CO CO Tf "Tf Tf Tf 1 1 1 1 1 1 Tf Tf 1 1 no »fO 1 1 i no no no no Tf Hf 1 1 1 1 1 Tf Tf Tf Tf -Tf 1 Tf 1 1 1 1 1 1 1 1 1 1 1 1 Tf Tf 1 1 1 Tf Tf 1 1 1 1 1 1 Tf Tf Tf Tf i 05 d 1 1 i ci o o 05 co d 1 1 1 1 1 1 d d 1 1 d CO 1 1 , d T-H T-H T-H CM Cl 1 1 i d d ci d t-h t-H 1 1 1 1 1 1 t-H ^H 1 1 T-H d 1 1 i d d d d CD -P> d Q . CO o' c § c ' d cj ^ <1 d H 5 h 5 '~v-'»-D d ►”5 a d ►“5 d d •“O § » ^ h b *- a. 3 a a <3££ O d 0) CD d o d p o > cn a M a c3 ci W « _c 'S O > m a_ « S'S WP> .2 ’w >5 -§ ~ © Pi w><$ C o o & o 'o o d rd GO CD CD _ a ® d sr W)«^ p a C ^ o px:- 1 - 1 d,rj.p o o--h © © CQr/)OWWj O OWpH P o X> aS >> P d CD K ® to TS • -H P Xi a o to c 3 £ a ® ® 2 5 « n a (. ji o a =02 02 fa. 2 ; ® ® fe C 3 cjO- KQPhPP^ 0 d ® 3 'p •£ ^-h c^ieo ^»oco n oooiO I M CO Tf IO o r^» OO 05 O ’—' 1-4 *-4 C^l Cl CO T »0 Cl Cl CM Cl o Cl t^» OC O O i—i Cl CO d Cl Cl CO CO CO CO ILLINOIS RIVER. 73 In Appendix B, Figures Nos. B-ll to B-48, are shown, hydrographs of daily river stages of the Illinois River at Grafton, Pearl, Beardstown, Havana, Peoria, LaSalle and Morris for the complete years, 1890 to 1927, inclusive. Hydrographs, Figures Nos. 19 and 20 cover the flood periods 1926 and 1927 for the stations Grafton to LaSalle, and Figures Nos. 21 and 22 for stations Grafton to Peoria in the period of the October 1926 flood on an enlarged scale to show the effect of the levee breaks. DISCHARGE. In 1900 Mr. Jacob A. Harman made seven measurements of the dis¬ charge of the Illinois Kiver at Peoria. These were made for the Illinois State Board of Health and are published in their report on “Sanitary Investigations of the Illinois River and Tributaries” in 1901 on page 135, with rating curves inserted at page 174. In 1903 to 1904, during the periods of high water, measurements were made of the discharge of the Illinois River by the H. S. Geological Survey at Havana, Peoria, LaSalle, Ottawa and Divine, also by the U. S. Engineers at 12-Mile Island, Pearl, Beardstown, Havana, Peoria, Henry and Ottawa. The results of the H. S. Geological Survey measure¬ ments are published in “Water Resources of Illinois” in 1914, and those made by the U. E. Engineers together with the few measurements made prior thereto in House Document 263, Fifty-ninth Congress, First Session. The more recent flood measurements of the Illinois River and its tributaries have been made by the U. S. Geological Survey, U. S. En¬ gineers and the Sanitary District of Chicago. In Water Supply Papers published annually by the H. S. Geological Survey are to be found the results of other stream gages in Illinois. They are made in co-operation with the State of Illinois, an arrangement whereby the work is done by the observers of the H. S. Geological Survey and the files with the results are kept for reference in the office of the Division of Waterways in Chicago. The curves in Figure No. 23 are reproduced for the purpose of com¬ paring the discharge measurements before the era of levee construction and shows three (3) rating curves, as follows: (1) by Jacob A. Harman from discharge measurements made in 1900; (2) by the U. S. Engineers from discharge measurements made in 1904 and (3) by the U. S. Geological Survey from discharge measurements made 1903 to 1906. PRESENT CONDITION OF RIVER AS LEVEED. The levee construction in the lower Illinois River Valley, which was commenced before 1900 and continued until about 1922, altered ma¬ terially the flow carrying channel of the river. About 1922 nearly all the levees were completed that brought the channel to the condition which we have today. The last of the levees to be constructed were started from 1918 to 1921 and were nearly completed in 1922. Since the completion of the levees there have been three main floods. The floods of recent years of great magnitude were in 1904, about the time of 74 FLOOD CONTROL REPORT. the beginning of levee construction, 1913 when it was well under way, and 1916 which was abnormal because of the breaking up of the ice forming jams above LaSalle and causing irregular flow. In 1922 the following districts were probably still under construc¬ tion : District. Organization. Area in Acres. Chautauqua . 1918 3,500 Thompson Lake . 1918-1921 5,600 Seahorn. 1919 1,470 Lost Creek . 1920 2,400 Valley City. 1920 4,750 Since 1921 some of the levees have been strengthened and raised. LIST OF DISCHARGE MEASUREMENTS. The details of the more recent discharge measurements, only a few of which have been published, are given in Table No. B-4, Appendix B. These measurements were made under the present river conditions and are those used in the derivation of discharge rating curves and diagrams. They show the river stages at the time of observation, the areas, depths and widths of sections and the authorities. a. Methods. —The U. S. Engineers and the U. S. Geological Sur¬ vey observed the velocity at two-tenths and at eight-tenths of the depth below the surface and applied a co-efficient of 1.00 to obtain the mean velocity at each station or station area. The Sanitary District of Chicago observed the velocity at sub-surface points either one foot or two feet be¬ low the water surface and applied a co-efficient of .90 to obtain the mean. b. Equipment. —Price meters were used by all observers and in general these were of the small Gurley type—in a few cases the large size meter was used. c. Rating .—Meters of the Sanitary District of Chicago were rated when purchased and once a year thereafter. Copies of these ratings in¬ dicate but slight seasonal changes in rate. Meters of the U. S. Geological Survey and U. S. Engineers are rated periodically. d. Rate Comparisons .—A comparison of meter rates was made by observers of the Sanitary District of Chicago and U. S. Geological Sur¬ vey by running meters simultaneously side by side at Beardstown on April 28, 1927. The results showed the U. S. Geological Survey meter giving velocities 2.7 per cent greater than the Sanitary District of Chicago meter. e. Velocities in the Vertical Plane. —Only a few measurements were made by any of the authorities to determine the variation of the velocity in the vertical section to test the velocity co-efficients which were used. On account of variation in discharge by different observers where measurements were comparable, a set of velocity measurements in ver¬ tical plane were later made jointly by observers of the U. S. Geological Survey and the Sanitary District of Chicago to check the co-efficients used. The results of measurements made at Peoria, Havana and Beard¬ stown made in December 1928 indicate that there was no appreciable error in co-efficient. ILLINOIS RIVER. 75 f. Comparison of Observations .—At Beardstown on April 28, 1927 simultaneous measurements were made of the discharge of the river by observers of the TJ. S. Geological Survey and the Sanitary District of Chicago with results shown in Table No. 14. TABLE NO. 14—COMPARISON OF SIMULTANEOUS DISCHARGE MEASUREMENTS. Date. Observer’s number. Authority. Observed discharge C. F. S. Residual from mean C. F. S. Percentage variation. April 28, 1926... .. .. 44A U. S. G. S. 87,600 4,020 4.8 April 28, 1926. -.. .. 44 S. D. C. 79,560 4,020 4.8 Mean.. - . - - _ _ 83,580 Difference___ - - 8,040 9.6 At Beardstown two measurements were made of the discharge on different years under similar conditions of stage and slope such that the flows should not differ materially and gave results as follows: TABLE NO. 15—COMPARISON OF DISCHARGE MEASUREMENTS MADE IN DIFFERENT YEARS WITH SIMILAR FLOW CONDITIONS. Ob- Stage. Difference in elevation. Ob- Date. serv¬ ers num¬ ber. Author¬ ity. Bath. Beards¬ town. La- Grange. Bath- Beards- town. Beards- town- La- Grange. server s dis¬ charge C. F. S. Oct. 16, 1926. 39 S. D. C. 453.36 452.77 449.81 0.59 2.96 77,190 78,000 Apr. 26, 1927.. 40 S. D. C. 453.26 452.35 449.28 .81 3.07 CURRENT METER DISCHARGE MEASUREMENTS CONDITIONS. A tabulation giving the condition under wdiich the flow was meas¬ ured at the upper stages, will be found in Table No. B-5, Appendix B. On October 5th the water was over the low^er chord of the Beardstown highway bridge for 740 feet out from the right abutment and debris w r as lodged along the upstream side of the bridge. One would expect under such conditions, w r ith the water running thru the debris and steel work, that the flow in the upper tw r o feet of the section would be retarded for a short distance above and below r the bridge. The current meter was submerged one foot below r the water surface, consequently even the flow measurements at elevations above 451, which are the most reliable source of information from October 5th to 12th, are probably too low. STAGE DISCHARGE RELATION. Ordinarily discharges are referred directly to the stage of a stream at the gauging station. The gauge heights are platted as ordinates and the discharges as abscissa, curves of discharge are then drawn through the intersection points giving the stage discharge relation. These are called rating curves. Observations falling to either side of this curve 76 FLOOD CONTROL REPORT. are by some 'authorities corrected to the curve at the same stage by the rule that for a constant stage the discharges vary as the square root of the slopes. This is based on the Chezy Formula v = c V r s or, since q = a v, by substitution q = a c V r s, then for a constant slope— q x acr ^ s x % s^ 2 q 2 a c r 1/2 s 2 1/z s 2 1/z On most streams for any stage there is very little variation in the slope or fall at the gauging station. At several places on the Illinois River, however, due to the back-water effect from the inflow of tributary streams and from the varying stage of the Mississippi River at the mouth there is a considerable variation in the fall at any stage and, con¬ sequently, discharges will fall far apart on either side of the rating curve. In other words, the curve will not always correctly give the dis¬ charge for the stage, and discharge measurements will give discharges that will vary considerably from that indicated by the curve, sometimes residuals being as much as 25 per cent or more. A break in a levee causes abnormal conditions such that no regular stage-discharge or slope-stage-discharge relation exists while the district is filling and unless discharge measurements are available, the discharges can only be estimated or approximated. RATING CURVES. The rating curves of the U. S. Engineers are given in Figure No. 24. Figure No. 25 is a rating curve of the Sangamon River at Oakford, and Figure No. 26 of the Sangamon River at Chandlerville. The rating curves of the TJ. S. Geological Survey for the Illinois River and tribu¬ taries are given in Figure 27. The rating curves of the TJ. S. Geological Survey, U. S. Engineers and the Sanitary District of Chicago at Beards- town are compared in Figure No. 28. STAGE-SLOPE-DISCHARGES. To obtain a basis for reference that would take into account the slope or fall as well as the stage, diagrams were developed that give at once the relation of the stage (e), the slope (S), fall or difference in elevation (F) and the discharge (q). Inspection and comparison of hydrographs of stages, discharges and slope or fall disclosed that in a general way the variation in discharge has a definite relation to the stage at the gaging station, and to the slope, or fall, to a gage immediately above or below the gaging station. It was also determined that for practical purposes this difference in elevation bore the same relation to the discharge as the slope at the gaging sta¬ tion. This was observed to be the case by inspection of the hydrographs of stage and fall when platted on the same sheet with the discharge- graphs. The discharge diagram is based on the Chezy Formula. ILLINOIS RIVER. 77 Formula v = c r 1/2 s 1/2 . At any stage the discharge varies as the square root of the fall or slope. s % f % q XX X Where q , s and f are respectively the mean discharge, slope and mm m fall of a discharge measurement, or center of gravity of a group of measured discharges, and q and s are respectively any other discharge X X and its corresponding slope. From this formula “f” is computed for every 10,000 c. f. s. of dis¬ charge at the stage of an observation or group of observations. Figures Nos. 29 and 30 are Discharge Graphs at stations Peoria to Hardin for 1926 and 1927. METHOD OF CONSTRUCTING A RATING DIAGRAM. To illustrate the method of constructing a Typical Eating Diagram, Figure No. 31 was drawn from seven groups of actual discharge measurements made at Peoria. The following is an explanation of its construction: (1) Plat each discharge referred to its stage as ordinate, and to its fall, Peoria to Pekin, as abscissa. (2) Note the clusters of observations in close agreement as to stage, fall and discharge, such as Obs. Nos. 8 and 10, also Nos. 56 and 55. Compute (see Table No. 16 following) the mean or center of gravity of each cluster as (b x ) and (b 2 ). For each center of gravity compute the Co-ordinates for a common discharge, as 30,000 c. f. s. Cluster b x gives a fall of 1.08 at its stage of 456.67, and cluster b 2 a fall of 1.04 at its stage of 456.37. Use the means,—fall = 1.06, stage = 456.52 and dis¬ charge = 30,000 c. f. s. as group (b). Similarly compute and plat sets (a) (c) (d) (e) (f) and (g). (3) Draw a smooth discharge curve A B (30,000 c. f. s.) thru the points a, b, c, d, e, f and g. Other curves as CD (40,000 c. f. s.) etc. can be similarly obtained. Take off (as noted on the plat) the fall (f ) from this line at every foot of stage. From the fall (f ) as m m scaled and the discharge (q ) = 30,000 c. f. s. on each foot of stage m compute the discharge q for every tenth or two-tenths of a foot of fall X over the desired range (in this case from 0.8 to 3.0). TABLE NO. 16—TYPICAL COMPUTATION FOR GROUPING DISCHARGE MEASUREMENTS. FLOOD CONTROL REPORT. Reference discharge. q X 30,000 30,000 30,000 Observed discharge. (q ) m 44,000 41,200 42,600 33,640 40,620 37,130 Observed fall Peoria to Pekin. (f) 2.04 2.31 2.18 1.45 1.75 1.60 Elevation Peoria. (e) 456.96 456.38 456.67 456.42 456.32 456.37 456.52 XI - 3 O u 0 c 3 > „ o C CX! o o a £'.3 ~ ■Q 3 O C GO c a o s CO to to to c c 3 © § £ i co • CO OQ S- . G 0 0 H mm m D £> ILLINOIS RIVER. 79 (4) Establish discharges as co-ordinates on the same sheet so that discharge 10,000 c. f. s. corresponds to fall 1.0, 20,000 corresponds to 2.0, etc. Plat the falls (f ) computed for each stage and join the points X for each fall to form curve of fall. (5) This gives a diagram from which can be read the discharge for any stage and fall. COMPARISON OF OBSERVED AND DIAGRAM DISCHARGES. Observed and diagram discharges are compared in Tables, Nos. B-6 to B-10, which appear in Appendix B. The differences in discharge are called residuals. Where the meas¬ urements are all made in one period and by one observer, a diagram derived from that will generally have small residuals for the reason that a diagram is made to conform to the observations. Observers making measurements in different periods when condi¬ tions vary will obtain results which may give a diagram with larger or smaller residuals. This is due to several reasons. There may be a per¬ sonal factor, or it may be due to the different methods of observations, where it is noted that one authority finds his results giving plus residuals, while another working in a different period will obtain from his results practically all minus residuals. This condition may, however, be due to the fact that references to stage and fall is not an absolute measure, but it considered a better criterion than other measures. DIAGRAM AND RATING CURVE DISCHARGES COMPARED. There is given in Appendix B, Tables No. B-ll, B-13 on which are compared diagram and curve discharges. At the higher discharges the slopes vary, more than those of the lower stages, and unless all are reduced to a common slope for comparison, the disagreement obtained as in Figure No. 28 will occur. RATING DIAGRAMS. Eating Diagrams have been prepared on a large scale for use in the study of the discharges at the following places, namely: Peoria—Referred to Stage at Peoria and Fall Peoria to Pekin. Havana—Referred to Stage at Havana and Fall Havana to Bath. Beardstown—Referred to Stage at Beardstown and Fall Beardstown to LaGrange. Pearl—Referred to Stage at Valley City and Fall Valley City to Pearl. Hardin—Referred to Stage at Kampsville and Fall Kampsville to Grafton. DISCUSSION OF DISCHARGES. The discharge measurements that are available and used in this report were made by experienced observers. Reference has been made to the adverse conditions encountered, such as levee breaks, inflow from flashy tributaries and accumulation of debris on bridge sections. Meters have been rated periodically to determine whether or not there has been a change in rate during the season. It is probable that 80 FLOOD CONTROL REPORT. temporary changes in rate would be detected by the use of a second meter during discharge measurements by running meters simultaneously on the gaging section daily. Very few observations were made by any of the authorities to determine the variation of velocity in the vertical plane. It is probable that a more accurate determination of the discharge would be obtained if, thruout a series of measurements, such observations were made at several stations in the cross-section and while the water is at high, inter¬ mediate and low stages. These studies reveal the necessity for more gages to be read in time of flood flows for better determination of the changes in slope. It would be possible to detect whether or not personal factor enters into the measurements if observers would periodically make simultaneous measurements of the discharge at the same station. Thus we find that at Havana measurements made by the U. S. Engineers are relatively high as compared to those of the Sanitary District of Chicago when referred to a common rating curve or diagram, but they were made at different periods, in different years, under different conditions and using different methods. If each had made two or three measurements in the authorized seasons, and simultaneous with those of the observations, a better analysis of the measurements could be made. MAXIMUM STAGE. Investigation of the height to which the river would have risen in the flood of 1926 had there been no levee breaks has been made a subject of considerable study. They led to the development of normal back water curves. Also calculations, involving discharge and storage, were made to determine the normal maximum stages. As the volume of flow entering a section of the river must be either passed along or stored, the inflow and outflow-storage have been equated in various periods. A balance of flow for the period October 1st to October 19th. Table Xo. 17 has been drawn. It shows how much of the flow in a definite period remains unaccounted for when the equation I-f-T+D = O+S+L, in which I is the inflow passing a river section, T the inflow from tributary, D the outflow from levee districts, 0 the outflow thru the lower river section, S the quantity stored in the reach of the river and L the quantity discharged into the levee disrticts. In the period from October 5th to October 12th the total quantity dis¬ charged into the levee districts at crest stage is known. (See Table Xo. 18.) SECTIOX III—FLOODS. discussion of floods of 1904, 1913, 1922, 1926 and 1927. Floods are of various types and differ according to the distribution and intensity of rainfall and the condition of the watershed to facilitate the rapidity of run-off from the tributaries into the main stream. The floods of the past quarter century on the Illinois River have been investigated and studied more than those preceeding because the TABLE NO. 17-BALANCE SHEET OF FLOW. ILLINOIS RIVER U>OOMO)OOOTfOOO!0 Unac¬ counted for (mean per day) • Xf—X 2 ^r^W05NMCOX>00(NO TfOrHOlONlOlOMlOiHTf iQrftiHCI 1 rHNinOtOTfn H—h 1 + IjH—Fiji 1 + 1 Total out. O+S+L 247.850 506.650 373,060 312.640 700.650 563,380 356.850 822,250 537,170 324,620 688,610 640.640 Unac¬ counted for. X? GOO 'OOOOOO 'O ' t'-OO iN»OHiOOiC i O i I-H lO iMONrHON ICO 1 - ~ 1 1 - 1 'rT iXTt'OiOC’H 105 i CO 1 NCOCON 1 03 1 1 1 1 1 1 1 Through levees. 0 74,850 0 72,300 0 147,150 0 89,900 Storage. s / oooooooooooo CON(NO’HrHCC(MP:NO'rH ’^rHTfCOWfNNOCCCO’f MfNOOCDOCOTfNi-icCNCl WrlHCllCTfOOOCDNHH 1 1 1 1 Out¬ flow. Oe 203,640 385,050 391,480 241,970 568,990 526,880 241,970 568,990 527,050 300,950 552,410 653,050 Total in. I+T 247.850 506.650 373,060 312.640 700.650 563,380 356.850 822,250 537,170 324,620 688,610 640.640 Unac¬ counted for. XI i i i i i i i c~D i I i Oi 1 1 1 1 1 Tti 1 i i oo • • • 1 • Id 1 CO ll-llllll-l- i i i i i i i i C'l i io ii i i I i i i • CO II 1 1 1 1 1 1 1 II 1 1 1 1 1 1 1 Levee dis¬ tricts. Dd oooooooooooo O 1-H CO CO CO lO CO O OO i“H T—H y—( Tribu¬ taries. Tc 82,550 122,150 54,480 109,000 315.600 161.600 191,550 437,750 216,180 60,410 119,620 66,730 Inflow. 16 165,300 384,500 302,350 203,640 385,050 391,480 165,300 384,500 302,350 241,970 568,990 527,050 Days. -rf t''- N N NrfNN^NN Dates—1926. To.a i0(NQ»0C4Qi0(MCu0C10i r-H r-H »-H r —i r—I t— 1 i-H XXXXX+zXXX+jXX 0©0©00©©0©00 OOOOOOOOOOOO From.o r-UO(Mr-UO(N»-'lO(MTHlO(M r—1 r-H r—1 »-H ooooooo©©©©© OOOOOOOOOOOO Reach. To. Havana..- Havana__ Havana_ Beards town_ Beardstown. _ Beardstown. _ Beardstown, _ Beardstown_ Beardstown_ . Pearl... -.- Pearl_ Pearl. .. ___ From. Peoria.— Peoria. . Peoria__ Havana- Havana. . - Havana_ ... Peoria. ... Peoria.. Poeria.. Beardstown_ Beardstown_ Beardstown_ a o as to a c 3 .02 .. cl Pi *§ § GG > ss "O o a> o > o O. &C/2 cc -Q-- OS 5 © CD > .Ztf § £ CV * P-1 C ^ 12 *2 « • ~ C 3 ©g bC^ Pi c 3 .. X c g £ O GG 0=3 « 4 H © CG > cS Pi » © GG CG H £ § O -m T3 J © CG § b£) ggs - S> Kf c o cS -m CD to c 5) o Si m GG © © > © GQ p 3 c3 © Pi ^3 bO 3 O Pi rS - 4 ^ c3 ® S.g X-2 © Q " © © © -j Pi o CG e *o © © **-» ca> -p> o —6 F C 82 FLOOD CONTROL REPORT. reclamation in the valley, beginning about 1900, so increased the value of the bottom lands, that a knowledge of the effect of alteration of the channel became a matter of economic importance, increasing as the im¬ provements spread over a greater portion of the area. In 1904 a flood crest was built up in a period of some two months, gradually increasing the stage at all stations from LaSalle to Grafton, culminating in a more rapid rise for ten days preceding the crest, at the rate of approximately four to five inches per day at Beardstown, Havana and Peoria. The crest moved down stream at a uniform rate from Peoria to Pearl and reached Grafton about the same time as the crest of the Mississippi Kiver flood. The next large flood, that of 1913, came when the levee construction was well underway. Its peak was built up more rapidly. After having been at bank-full for the preceding two months, it suddenly rose at an average rate of 10 inches per day at Beardstown, Havana and Peoria. The crest moved down stream at a very uniform rate from LaSalle to Pearl and also synchronized at Grafton with a crest on the Mississippi. The 1922 was the first large flood to occur after levee construction had brought the channel into its present contracted condition. The building up of the flood from bank-full was steady for a month, culmin¬ ating in a uniform rise of six inches per day at Beardstown, Havana and Peoria for five days as the crest approached. The rate of movement down stream was the most uniform of any flood of recent years, all the way from Morris to Grafton and arrived there at exactly the same time as a Mississippi crest. This flood provides the best data for study of unobstructed crest wave travel. It was made the subject matter of a special report, published in 1922 by the Division of Waterways entitled, “Floods in Illinois.” The flood of October, 1926, the record flood to date for stages in the middle reach of the river, has received its due share of observation, investigation and study. The hydrograph shows that it was built up to a considerable height in September, then receded and began to rise again on October 1st. The rate of rise was nine inches per day at Beardstown, and eight inches per day at Havana. The movement of the crest down stream was interrupted by the in¬ flow from the tributaries. From the first of October the Sangamon Elver at Chandlerville was rapidly rising until the crest on the afternoon of the 6th, then it proceeded to fall rapidly for the next two weeks. The effect upon the Illinois River profile is indicated in Figure No. 32, in which the profile of October 5th is drawn as a horizontal reference line and the stages of the following two weeks are referred to it. The same depressions in the lines, due to the levee breaks occurring between the 5th and the 12th, appear here as on the regular profile. Browning is at the mouth of the Sangamon. Note that the maximum effect every day is at this place. Following the line for the 7th a depression is found at Copperas Creek when the levee breaks caused the withdrawal of water. Below Copperas Creek the depression was counteracted by the large overflow from the Sangamon on the 7th and 8th. The crest ILLINOIS RIVER. 83 wave coming down stream started from Peoria on the 9th, passed Pekin and Kingston Mines on that date, and continuing without accre¬ tions would probably have passed Browning on the 10th. The tributary inflow and the breaking of levees influenced the cresting below Kingston Mines so that it occurred on the same date, October 12th, at all stations from there to Valley City. Here the crest wave was met by one coming up stream from Grafton, also depressed on account of levee breaks. The Mississippi crested in advance of the Illinois on the 6th, after which in falling it lowered the Illinois stage. This condition terminated the ad¬ vance of the crest wave at Valley City. During the period from the middle of September to the middle of October the engineers of the Sanitary District of Chicago made almost continuous discharge measurement of this flood at Havana, Beardstown and Pearl; these measurements, although made under adverse conditions and subject to the criticism of being made from sub-surface velocity observations only, are considered reliable and of such accuracy as to make one of the most valuable contributions of hydraulic data available in the Illinois River Valley. The 1927 flood differs from the others in that it is made up of a high water period of four months, upon which there were created by short period of intensive rainfall distinct crests, of which one in April was the highest. The numerous districts that were flooded in October, 1926 remained full of water, creating additional areas of storage and thus affecting the flood flows, but in a more uniform way than at times when the levees broke. The flood crest moved down stream similarly to that of October, 1926, Flood (Figure No. 19), progressing regularly from LaSalle to Valley City. The Mississippi River crested a few days in advance of the Illinois. DISTINCTION BETWEEN CREST PROFILE AND PROFILE OF A DATE. The highest elevation that a flood reaches at the crest generally appears at an up-stream station earlier than at a station further down¬ stream (disturbances causing exceptions) and the line joining the crests is called the “crest profile.” The line joining the simultaneous eleva¬ tions on a date is the profile of the date. Thus on April 22, 1927, Figure No. 19, a crest profile from LaSalle to Peoria compared with date profile would be as follows: Station. Elevation of water surface for crest profile. Date, 1927. Elevation of water surface for profile of date. Date, 1927. Difference in elevation. LaSalle.. . . . . 464.1 Apr. 22. 464.1 Apr. 22_ 0 Henry_ 461.7 Apr. 23-.-. 461.2 Apr. 22_ 0.5 Peoria_ 460.2 Apr. 24_ 459.8 Apr. 22_ 0.4 84 FLOOD CONTROL REPORT. The run-off from the watershed below the gaging stations on main tributaries and along the small tributaries is an item of considerable moment when accounting for run-off between river discharge sections. This item has been taken as a percentage of the discharge at the main tributary gaging station, which is determined as the ratio of the area of the watershed above this station to the area of the watershed below it and between the river sections. Such a discharge volume is indicated by hatchures on the Crooked Creek Discharge Graph at the bottom of Figure No. 33. LEVEE BREAKS. In the October, 1926 flood there were 17 breaks in the levee, as follows: District. Big Swan . Chautauqua . Coal Creek ...... East Liverpool . . . Fairbanks . Hartwell . Hillview . Kelly Lake . Kerton Valley .... Lost Creek . Mauvaisterre . McGee Creek . Meredosia Lake . . Pekin and LaMarsh Scott County . Valley City. West Matanzas ... Date of Break-1926. Acres. September 3 11,850 October 9 3,500 6,390 October 5 2,765 October (2 or 10) 8,000 ■ September 8 8,650 September 4 12,318 October 6 985 October 7 1,741 October 4 2,400 September (8 or 9) 3,980 October 7 10,080 October 7 3,700 September 1 2,674 September 9 9,200 September 8 4,750 October 7 2,679 Total Acres. 95,690 A number of the levees of the larger districts in the lower reaches of the river broke in September, so that the districts were filled at the time of this flood and did not materially affect the uniformity of flow, but acted as increased river storage area. The breaks occurring in the vicinity of gaging sections had a marked effect upon the flow causing irregular velocities, due to the outflow of water in the districts, and they occurred while the river was rising. After the crest as the stage lowered the water was drawn out of the districts and increased the volume to be carried, thereby affecting the flow for a considerable period. STORAGE AND LEVEE DISTRICTS. Table No. 18 gives the quantity of water which the various districts stored at the time of high water and shows the eleyation of > this high water and the area in acres in the districts at that time. Table No. 19, is very comprehensive and gives the storage capacity of all of the levee districts in the Illinois River Valley. This indicates the possibilities of the use of the levee districts as storage reservoirs. ILLINOIS RIVER 85 TABLE NO. 18—STORAGE IN LEVEE DISTRICTS—1926. Reach. Date of break. Levee district. Miles above Grafton. Eleva¬ tion (M. D.) high water 1926. 1926 high water area. 1926 hig capa In feet. h water city. Cubic feet per second per day. Peoria to Havana.. Peoria to Havana_ Peoria to Havana... Total.... 1926 10-5 10-5 10-9 East Liverpool_ Banner_ Chautauqua_ 128-132 137-146 124-130 456.1 457.2 456.1 2,300 2.780 3.780 38,800 41,600 69,300 19,400 20,800 34,650 8,860 149,700 74,850 Havana to Beardstown_ Havana to Beardstown_ Havana to Beardstown_ Havana to Beardstown_ Total_ _ 1926 ' 10-6 10-6 10-7 10-7 Lacey-Langellier_ Kelly Lake_ Kerton Valley_ West Matanzas. 118-119 100-103 112 113-116 455.0 454.5 454.8 454.8 5,290 1,040 1,770 3,340 69,000 15,200 13,900 46,500 34,500 7,600 6,950 23,250 11,440 144,600 72,300 Beardstown to Pearl.. Beardstown to Pearl.. Beardstown to Pearl.... Beardstown to Pearl_ Total_i_ 1926 10-5 10-5 10-7 10-7 Kerr__ Kerr-Crane_ Meredosia__ McGee’s Creek. 78-79 75-78 66.5- 67.5 67.5- 75 450.3 450.3 450.1 449.3 470 1,040 5,300 10,900 4,400 15,100 36,300 124,000 2,200 7,550 18,150 62,000 17,710 179,800 89,900 TABLE NO. 19—LEVEE DISTRICTS IN ILLINOIS RIVER VALLEY, SHOWING AREA IN ACRES AT FLOOD PLANE OF 1926 AND STORAGE CAPACITY BELOW THAT PLANE, IN ACRE-FEET. (1) District num¬ ber. (2) Name of district. (3) County. (4). Elevation 1926, H. W. (5) River station. (6) Area at flood eleva¬ tion. (7) Storage, acre- feet. 1 Hennepin.... Putnam_ 462.1 1,081 851 2,600 840 41,000 2 East Peoria.. __ Tazewell_ 460.5 10,200 35,300 15,500 3 Pekin and LaMarsh... Peoria ..._ 459.3 805 2,260 1,120 12,700 2.780 2,340 2,470 3.780 5,050 1,181 311 4 Rocky Ford_ Tazewell_ 458.7 790 5 Spring Lake_ Tazewell__ 456.9 744 206,600 41,600 38.800 41.700 69.300 92.800 12.300 2,100 69,000 46,500 10.700 13,900 6 Banner Special_ Fulton and Peoria.. 457.2 749 7 East Liverpool_ Fulton__ 456.1 686 8 Liverpool_ Fulton_ 456.1 672 9 Chautauqua_ Mason__ 456.1 665 10 Thompson Lake_ Fulton_ 455.4 651 11 Crabtree (private) open_ Fulton_ 455.5 648 12 Spoon River (private) open .... Fulton_ 455.5 648 13 Lacey..] Fulton__ 455.0 622 5,290 3,340 1,300 1,770 2,930 14 15 Langellier___/ West Matanzas..... Fulton. ... 454.8 602 16 Seahorn__ Fulton 454.6 610 17 Kerton Valley___ Fulton_ 454.8 613 18 Big Lake_ Schuyler. 454.6 557 47.200 15.200 99,300 19 Kelly Lake.... Schuyler. 454.5 535 1,040 6,650 1,290 4,900 6,760 20 Coal Creek.... Schuyler. _ 453.6 469 21 Lost Creek... Cass_ 453.6 475 10.300 57,700 121,000 27,600 36.300 0 22 Crane Creek... Schuyler__ _ 452.3 445 23 24 25 South Beardstown_\ Valley.../ BigPrairie.. ..... Cass__ 452.8 455 Brown_ 451.6 433 2,070 5,300 26 Meredosia Lake.. Cass and Morgan... Morgan.. 450.1 401 27 Willow Creek. .... 395 28 Little Creek (Kerr, Kerr-Crane) McGee Creek.... Brown__ 450.3 405 1,510 10,900 19,500 124,000 29 Brown and Pike_ 449.3 375 86 FLOOD CONTROL REPORT. TABLE NO. 19—Concluded. (1) District num¬ ber. (2) Name of district. (3) County. (4) Elevation 1926, H. W. (5) River station. (6) Area at flood eleva¬ tion. (7) Storage, acre- feet. 30 Coon Run___ Morgan and Scott.. Scott_ 448.5 365 1,300 3.600 9.600 5,400 12,100 10,800 8,910 1,800 19.800 93.800 64.800 129,100 96,000 91,900 69,700 31 Oakes (private)_1 448.2 345 32 33 Mauvaisterre_/ Scott County.. Scott_ 446.8 316 34 Valley City.... Pike_ 448.0 340 35 Big Swan... Scott__ 444.6 282 36 Hill view_ Scott and Green 442.2 246 37 Hartwell... Green_ 441.2 214 38 Fairbanks.. Green_ . 440.8 187 7i 880 8,610 820 39 Eldred... Green_ 440.3 147 103,200 3,700 88,900 41,500 40 Spankey_ Green . . 438.7 124 41 Nutwood_ _ Jersey and Green... Cass__ 438.6 100 9,610 6,200 *42 Hager Slough.. \ Grigg’s Chapel.../ 454.0 489 *43 * Note. —No levees. SECTION IV. BACK WATER PROFILE COMPUTATIONS AND COEFFICIENT OF ROUGHNESS V FLOW FORMULAS. Formulas for computing uniform flow of water in open channels have been derived using as a basis known physical laws and extensive research and experimentation on artificial and natural channels. These formulas are well understood and accepted among Hydraulic Engineers. Among those most universally used are Rutter's and Manning's modifi¬ cation of the Chezy Formula. Satisfactory results are obtained by the use of either of these formulas, provided proper coefficients of roughness are used. From these and other investigations we have concluded that while the Manning Formula can be applied with a very nearly constant value of coefficient “n” of roughness for a given channel condition, the value of the coefficient for Rutter's Formula varies not only with the con¬ dition of the channel, but also inversely with the slope of the water sur¬ face. For this reason and for the further reason of its marked simplicity as compared to the Rutter Formula, the Manning Formula has been adopted for hydraulic computation in this report. 1.486 2 / 3 y 2 The Manning Formula is as follows: v =-x R x S , in n which “v" the average velocity of the water in a given cross section; “n" is the coefficient of roughness; “R" is the hydraulic radius in feet; “S" is the slope or fall expressed in decimals of a foot per foot of length. The Diagram, Figure 34, for the Manning Formula platted on logarithmic scale, greatly facilitated the computations. With three known values of any of the four required, a S," “R," “n" and “v,” the unknown may be determined directly from the diagram. As an illustra¬ tion, enter the diagram at the intersection of “R" and “S" and follow the diagonal line “n v" to the diagonal “n" line representing the known value of “n" and read the velocity on horizontal line to the velocity ILLINOIS RIVER. 87 scale—or follow the “n v” line to the horizontal line representing the known velocity and read the value of “n” on the diagonal “n” line. APPLICATION OF FLOW FORMULAS. In applying any uniform flow formula to the condition of a stream such as the Illinois River, it is important that the value of the coefficient “n” be determined from as nearly as possible to actual flow conditions. The nearest approach to uniform flow in a natural stream occurs at flood crest, especially if the crest or trough stages persist for one or more days. For this reason particular attention was given to minor flood crests occuring in recent years, undisturbed by levee breaks, in the studies for determining the values of coefficients to be used in computing future flood heights. In general the cross-section available for flood flow consists of two parts having widely different hydraulic factors; (1) the channel section including the prism of the river channel below and above low water stage (1901), and (2) the over-bank area including the area occupied by flood waters on both banks and extending from the channel section to high ground or to the levees. For convenience the Illinois River from Grafton to LaSalle has been divided into 49 reaches, in length varying from 5,000 feet to about 40,000 feet depending on physical con¬ ditions. The average cross-section areas and top widths were determined for each reach based on elevations at center of reach and tabulated for each foot of elevation from bank-full stage to several feet above high water. Tables of these cross-section areas are included and more fully described in Table No. B-2 in Appendix B. of this Report. DETERMINATION OF COEFFICIENTS. The values of coefficient “n” Maning^s Formula for the river chan¬ nel section were computed as a basis, selected reaches of the river being used, between Grafton and Peoria, in which the over-bank section is so small that it has very little effect on the total discharge. Stages and slopes were used from a number of minor flood crests of recent years with discharge taken from the rating diagrams developed from discharge measurements. These computations disclosed nearly uniform values of “n” for channel and values of “n” for overflow well within recognized limits. These values of “n” when applied produce computed profiles, agreeing within small limits with observed crest stages at all gage stations. COEFFICIENT “n” FOR CHANNEL-SELECTED REACHES. Table No.. 20 gives the result of computations to determine the coefficient “n” for the channel section of the Illinois River, based on selected reaches between Grafton and Peoria, where levees confine prac¬ tically all of the flow to the channel section. Quantities “Q” were determined from the Rating Diagrams at Hardin, Pearl, Beardstown, Havana and Peoria respectively, with stages and slopes based on observed conditions, with the river thru each reach considered temporarily sta¬ tionary, either at minor crests or troughs; “n” value for the overflow section was assumed as .080. It will be observed that over-bank areas in TABLE NO. 20—COMPUTED VALUES OF “n” (MANNING’S FORMULA) CHANNEL SECTION OF ILLINOIS RIVER FOR SELECTED REACHES OF RESTRICTED OVERFLOW. “Q” BY RATING DIAGRAMS. STAGES AND SLOPES OF MINOR CRESTS 1923-1927. 88 FLOOD CONTROL REPORT Channel Section. a OOiOOOON lOCOOOWNO COCOCMi0^cOt'^^©CO’*r , CO’^'**«CM''^ , iOTj t>- © *-< *<*< CM *0 CM lO 1 -r-H CM v-H CM Is. 1 i—t 1 1 1 • > 1 1 cm to i ia © i 00©00*O”*rtN.U0i—1 r-tCOCOCO’^CMTt'© 1 Tt* 1C 1—1 CO CO CM © i CO tO 1 1 1 1 1 1 a ©©©©©©©©©©©©©©©©©©© oooooooooooooooooooooooooooooooooooooo ©©©©©©©©©©©©©©©©©©© Pi ^ © cm © to to © Tt- © © oo © © ©QO©©CO*0©’rf'lN*©iOCO©*—' © © © CM »—< tHMNiOWMffiOSOiflOKNCOOmOl-HtOO Ph CO^CC©©iC»0©tO©©T}'©iOiO©COCOCO CU>.NrH(MCDNC:C:iO*OiOCOCOO»0©tDCO iOCMTr. 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M — p—I w .a £§0^2 • ' o c3 O.S c3 ■ o W 03 GO ^ . oico 1-t ® III. «£ja * aa ” c^- 1-2^” -2 o £* “S*tj £ 03 o ffl >3 c3 (i c3 , tor-) a 3 Q- 3 'n W -£ iST3 c 3 9 —< >*- a & —• »: •— 2 -u g . C3 03 ” a a 03 O •>r . . cr o* GO CD at -*-3 0 0 .2 1* 00 ^ CO O ^ ^ 03 e 3 C3 ^ O.L, . a * 9-r* h ^ -4 > r* o c3 O n O C 3--7 d4 n£ «s § o 2 o^a -^ >. 03 .g.-SM l°,S is —1 c3 2 03 <13 S>PL, O' GO o CO CO a o «4-l c3 f-. 0 o © > CD 04 2 c3 M o 03 CM ag *< CM ^4 II. © CD 2^ O O 3 03 o.„ - § a Observed w. s. elevation. 456.22 454.07 451.58 450.60 449.23 447.96 446.90 GO 00 CM co O co"nT CO T-i CM **f CO O OO ^ Tf co t-h uo co cm '*~t i Tf CO CO CO Tt< TJ4 Tt< ^ -rti rf 430.2 424.1 no CO co OO 00 00 00 00 05 05 05 © T-H y—i 1 no r-H r— « r-H r-H H 1 r-H rH r-H rH t—H r-H 1 OO rH rH t-H Q d d d d d d d d d d d d d d a a a a a a a Cu Q< Q, a a a < < 03 © b£ c3 1 1 1 • 1 O ! m r-H ■ • • . • 1 C Z * 1 © 1 >1 eS.tJ 0 1 1 1 £ 8 1 • 2 ! O - 4-3 ti c ■go .2 *c 0 1 c 12 S a gg C CD H ci a t-t 0 T3 >> 03 03 •zz c. © Pd <13 a, c3a w« © PQ c3 1-1 2 C3 03 St>a > OQ a a 03 w c — 9 c3 03 WO TABLE NO. 22—COMPUTED PROFILE FLOOD CREST APRIL, 1926. GRAFTON TO PEORIA. 92 FLOOD CONTROL REPORT. CO o CO CM 00 00 ~a c £ • o >02-- o CO ^t 4 CM CO CM CO to 1-4 CO Tt 4 ^ CO CO *rp ^t 4 t-l 0 • C3 » b* O 'o Tt 4 -rp Tt 4 TJ 4 'Tfl T3 o CM CO o oo to P- oo 05 oo CO CO CO © to 0 d 1—4 CO o to CO oc o 1—1 CM CO CM CO 00 o CO 00 CO • o • • • err-- p« 05 T—H CO *rp CO oc 05 —> CM CO cc CO to to ZO r>. CM CM CM CO CO CO CO CO CO Tt« Tt« rt 4 rft ■*r > O © •rr Tt 4 Tf 4 ^f 4 TF -r Tf< 'TP o CO CO CO CM CM CM CO CO CO CO CM CM T-H CM CO CM CO CM • to to to tO C -t 4 T Tf 4 Tt« TF -r 4 4 rt< C CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM CM ’-£5 c o O o O o o O o o o o o O o o © © © o 0 CE 0 to to CO 05 o CO CO to o 05 00 CO to CO o CM oo © © c c3 Ph r^- OO 00 o P-i p^ 00 05 o o _h’ C5 CM © © © T-H T-H 1—4 CM T-H i—4 t-H 1-4 CM CM 1-4 CM CM T-H CM T-H T-H CM o CM o o © tO r- to to © o o tO to to o o © o OO CM CO CO to CM CO CO oo o OO to -"T ^t 4 cO © to eu o 05 o 05 CM CM o 05 p>. 05 oo OO oo oo © hH ^H o CM o to o o to o o o o o to o o © © © d 05 CO oo CO CO CO ^p CO CO oo CO CM to to 05 © Tt« © 0 05 to o to to CO p- CM CM CM CO to © I>- p>. << P^ 05 05 ^H t-H oo 00 CO 00 05 CO o CO © © T-H HH 1-4 CM CM 1—4 T-H T “' fH i-4 T-H T-H o o o o OO o © o o o o o o o o o © © o CO o o CM CO ^p CO to CO o o o to © © © c? t—H 00 T-H to T-H to CO CM o CO oo 00 © to 00 CO CO CO i—4 _| 1-4 CM CO 00 to CO y-4 CM CO CM CM CM to to to to to CM CM 05 oo CM r- 05 CM CM o —4 CM © > CM CM CM CM CM CM CO CO CO CO CM *r? CO CO c .c a ® on C c3 I > o a .110 oir © © © © © © © © T-H © © oor © © © oor oor © © i—4 © © T—4 © © © CM © © © © © © CM © T-H © © © OO p- T-H CO CM © CO Ph CM CO CM co © © © © CM *— 1 © OO p- 00 00 © © © © © © oo © o © © © © © © © © © 00 © © © CO © CO CM r- CO ■^f 4 © © © © © Ph © CO © oo CM CM 00 CM CO CO oo p^ 00 © © © © CM *"■ CM © oo CO © © © © © © © © © © © © © © © © © © c3 © © OO CM CM © 00 CM © oo © © to © CM © CM © 0 CM © OO © © © © CO 00 CM © © © © CO © < P- CO CM CM © © © © CM © Tt 4 © 00 CM © CO © © © © © © CO © II 0 Hf OO © CO © CO 'O 4 OO © T-H OO 00 oo CO © © © © HI Hf © ■'t 4 © T 4 CO 1—4 T-H CO ^t 4 Tf 4 CO 0 1’ C =! c3 © © © © © © © © © © © © © © © © © © Cl © © © © © © © © © © © © © © © © © © © © © © © © © © © © © © © © © © © © ^.5 T3 © © © © © © © © © © © © © © © © © © co O $ rt : . n o © oo o' © o © 00 o CO o © oo o CO © © © © T-H © CO T-H ©~ © © © © © d o c3 m CM . © 0) p- *£ © T-H «2 o Q< ^ s g3 w o CO © © o © o Oh © © © © © © © © oo © CO © © © © © © © © © o . «3 >>><” CO 0 > o o o 05 to o to • CM .2 • |{2 "d co 0 o to to oo" to 05 CO © © © © © CM oo © CM CM oo © CM 00 OC p^ p-T © © © © © © o to . p* 0 i b L Cg o © CM CM CM CM " *rp © © TJ 4 TJ 4 ILLINOIS EIVEK. 93 o CO CO o 4 co CM 05 05 CM CO wo o CM CO r^ 05 o t—H ^F CO TF -*F WO WO wo WO ^F ^f TF O 05 CO oo T-H 05 O WO o 05 05 oo CO o o T-H CO CM CO o 1 OO ^F CM oo CO WO oo CM CO WO o CO co L- OO 05 05 o t—H ,-H CM CO CO "F WO CO **F **f -rF TF -r TF ^p WO wo WO WO WO »o wo WO WO »o tF tf -*f Tt« ^f TF ^F ^F ^F -F ■ o J ° r-C O Sco O I ^ -r CM co r^. c 3 (h P-\X> o wo ; + a co *c *** o°° « On 0^ 94 FLOOD CONTROL REPORT. m fa W O <3 fa) Pi Q <; m X O i—i H <3 Eh m O X i—i o <3 0 iJ <3 eu i—i o w I—I « Ph Pi o fa m fa Eh <3 . Pi <3 l-H fa^ gg WO OEh 00,-1 fa fa) .<3 s< fa Pi fa < fa o H co fa Pi o Q O O fa fa Pi w > h—< Pi CO O W h-1 fa fa eo o w fa fa m <3 Eh (V if (- 03 fa o » fa _ m _. 2 © ■u K (4 S fall* 3 J 2t) « 73 2 6 rt © bfl Ph c3 o QQ >5 Ph o3 -fa> .ft CO fa5 13 © © Ph © 13 "S . 3 &CO-J © • 03 - 8 £> o 13 3 09 0) c fa . 2 ® "c3 O 85 O fa t, c3 fa t. o © bfi c3 o o o o o o o CO o o cO PO PO CO PO >> fa o o o o o o o 1 1 1 1 1 1 o o o o o o o 1 1 1 T3 * CO is- PC CO 1 1 1 5 £ O 05 l-H oq CO PO CO 1 1 1 fa ° 3 03 » 3 8° O O PO »o PO PO PO 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 • 1 Ph - © cs >5 fa >> cq o' -1 fa fa fa 03 8 H t- 53 >1 • -fa o ® K !d .00 ’E3 fa o ftCt ^cofa • 2 *^ M H c^>. o. »'& © o' 1 * 5 043 * fa C3 8 73 fa c a 03 W go O 05 fa'* kT « £ 3 2 Ph *- o i3Q o ' -1 3 ^3 a 3 • fa 2 -C *3 Eh o L 3 • M*3 ?ll <3 GO Ph © >§ GQ •— S c3 fa ® » W N Ph © a, oq §11 8 fa eo fa 1 3 O l is o o 1 ^ O .00 i ^i 1 o 1 fa ?o COO 1 , © 1 13 1 05 1 II 1 i-H 1 1 1 II 1 ^ ' II d 1 " \ o 03 ! 3C S i a & 1 ^ : II ( PO 1 II I PO ! ^ i ^ . ^ icofa 1 45 i « -4-5 1 -4-5 (U. s G. S. . mi. area ! «5 : a • -4-5 ! 03 i a ' c3 i '.fa 1 s 1 ! ja oq . • CD ^ • . Ph i S—< sq. i ! dr . rn ! dr ■ © ! 6 1 ■ 09 O o oq ft © a a © a o -P5 © 3 Ph © 0 o3 © Ph < >> Ph fl © a o ft © a 13 © a c3 © Ph o o © .d O © -d O o -*fa >> Ph C © a c3 © o PO i «H a 0) X <0 fa *5 o w 2 3 __, • <-H fa o cn ® 0 ) © > > 3 3 O O MCO |wd MCO CO o3 . . fafafa ^ fafafa <3 3 3 M M M pH pH pH ^ a ^ ^3 ^3^3 © © © CD QQ (73 fa QQQ TABLE NO. 24—COMPUTED PROFILE FLOOD CREST APRIL, 1927, PEORIA TO LA SALLE. ILLINOIS RIVER CM t 1 1 1 OP TjHOP O 40 O OO TJ C 3 CM 1 1 1 1 OP ^ CO rH OP 00 © O 1 1 1 1 0 O r-H rH r-H CM 01 CO CO 1 1 1 1 CO CO CO CO CO CO co co S-. 1 1 1 1 rrf -r ■rf 1 1 1 1 1 I 1 1 o 1 1 1 1 1 1 1 1 1 1 T 3 m CM rH 00 CO CO CO co co OP ^ CM CM r-H OP 0 00 O a CM CO CO Tt< to OP 0 CM 40 f'- CO r-H 40 OP r-H • n • • • • • • • • • • • • • • • • O 0 0 0 0 0 O r-H r-H r-H r—H CM CM CM CO " - 4-5 CO CO CO co CO CO CO CO CO CO co co CO CO CO CO • a -f Tf« TT § s o £ l ”3 O 0 0 0 0 0 O O O 0 O O O 0 0 0 0 40 O O O 0 O O Of IO 0 40 CO CO CO O CO CO OP OP OP CM OO CO OO CO CO CO CO CM r-H CM CO CM 00 CO 00 0 CO CO OP O 0 40 0 OP CO r-H 40 r-H OP ^rr OP CO > »H rH CM rH rH r-H r-H r-H CM d 40 40 to 40 40 40 to 40 40 40 40 o CM CM CM CM CM CM CM CM CM CM CM CM h 3 Cl O 0 O O O 0 O O O O O O o m i < o CJ 00 Tt« CM OP r-H CM CM OP CO CO c tf CO 40 40 00 Tt< CO CM c 3 CM CM CM CM CM CM CM CM CM CM CM CM 43 o O 40 40 O O O 40 O O O O O CM T* O CO O 40 cm CO -r Pk 40 OP CM CD 00 OP 00 00 to r-H CM CM O O O CO 0 40 CO co 0 0 0 0 o 3 OO r-H CO CO 00 0 O CM 0 r-H 0 CM O CO 40 OP CM OO CO OP 0 <1 O OO 0 CM 40 CO OP 00 OP cm" CM 40 40 CM CM CM rH rH rH rH r-H O O O 0 O 0 O O O O O O 40 O 40 O 0 O O O O O O Of OP CO CO OP Tf CM CM OP 40 40 rH CM OP CO CO Tt* OP O CO CO r-H r-H r-H r-H r-H rH CO CO CM rH CM 40 CO CM OO 40 40 OP 40 -'f OO r-H CO r-H CO CO > CM CM rH r-H r-H CM CM CM CM co O O O O 0 O O O O O 0 O Ch O O O O O 0 O O O O O 0 O OO OO CO OO 00 CM CM OO OO OO 00 CO o pj O O 0 O 0 r-H r-H O O O 0 0 0) GO G c3 40 40 -Q CO OP CO 40 CO OP CO 0 CO pH (H CO CO CO Ttl 40 CM 40 to co rH r-H 0 9) ► o r-H r-H r-H rH r-H rH r-H rH rH rH O 0 O O 40 O O O O O 40 O CO O O CM CM OO CO CM CO Ph O 00 r-H 40 r-H ^ 40 CO CM CO CO CO co CO r-H CO 40 N r-H 00 r}T r-H d 0 0 0 O O 00 O O O <0 O CO -t» O r- 40 O OO CO CO CO © op CO 0 00 O r-H OP O CM CM 40 OP << 0 CO CO CO O 0 O OP CO r-H '-f CO 40 CO 0 OP rH CO 00 r-H CO OP r-H rH r-H 1 40 l CO 0 -r CO 00 CM O 00 II 1 0 1 ^ -f r-H CM 40 tO -f r- 40 40 1 0 rH O O r-H 0 0 O O 0 r-H CM 0 ) 1 fl 1 0 0 O O O 0 0 O O 0 O O • 0 0 O O O 0 0 O O 0 O O • 0 0 O O O 0 0 O O 0 O O c3 • 0 0 O O O 0 0 O O 0 O O CO *— .S T 3 1 1 1 © 0 0 0 O O O 0 0 O O 0 O O hfl 0 0 0 O O O 0 0 O O 0 O O u •» CO CO r-H OO 40 O CO TT S (S' . pO-g-tf “ CD- CO CO CO CO 40 40 CO CO CM rH O OP 40 40 40 40 40 40 40 40 40 40 40 40 TJ 0 O 0 OO CM O O 40 O 0 • O O O © co r- rrti 0 to co • 4 - 4 c <3 + .5 + si 0 0 a r-H r-H Ch © X OP p CO CO •jn r3 00 CLrH 03 '“H X c 3 +-P m 8°° Pk 00 00 OP OP .2 r-H 13 0 0 08 OP 0 r-H U C T 05 no p-T CO no no no rf T-H rH CM CO no iO CO CM UO rH 05 > CO CM CO CM T-H r-H oo oo 05 o oo CM a> CM cm CM CM rf CO CO o o o O o o o -4^ £ ■ ‘ ■ ’ ’ M M no C3 rf T* r* •* CM CM CM CM CM CM CM c c o o o O o o o • • • • • • • o3 05 no oo CM CO 05 00 oo 1^ o 05 05 T-H Pi rH CM CM CM o O o no o o • CO CO CO no 1^ o c3 O t-H no no CM o CO rt< T-H CO CO CO rH CO <1 rH CM T-H T-H T-H T-H o o oo CO 1,120 2,230 o o rH 29,400 26,750 O o no CO CM no CM CM CM o OO rH CM CM CM CO rH CM CO a o • rH o > a Rutter u OO o rH .112 no CM T-H .126 .108 .106 .105 w) o o o O o O O c rH rH rH o oo OO OO •rH rH rH rH T-H o o o 5 C " * ' ■ ■ ■ ■ c3 M t o no no no o CM rH no CO no CO Tf« Pi CO no 05 o3 0) M o o o o o o o CO o CO o o o CM CM o 05 o rH CM no no CO CO oo CO CM rH CO no CM no rH rH no CM CO O OO CO oo oo Oj CM no no CO o O CM O O O o o O O O o o o o o o o o o o o o o o o o o o o o II .1. 8 « I c Q< S c3 O c3 -£ GO 12 o O O o o O O O O O o o o no no O CO no CO CM OO CO o O no no OO OO rH 05 CO CM oo o CO CO CO o o o 05 05 05 OO t^o CO CO CO CO CO CO CO no no no no no no rt« a> hi) * . m - O o o CO no no no t-- CM + 4- + o O rH 05 no 05 no co CO CM 05 CO no 00 O CM 05 CM O CM 05 CM rr oo rH CM CM CM CO ^ no no no CO C3 -4^> O So rig o CO^* ILLINOIS RIVER. 97 profile agrees very closely with the observed stages at all gaging stations between Peoria and Peru. At the LaSalle highway bridge the observed stage was 0.7 foot higher than the computed stage, which discrepancy may be accounted for by the enlargement of the valley immediately below the highway bridge and the obstructions offered by railway and highway embankments opposite LaSalle, for which adjustments in the computations have not been made. CONCLUSIONS ON VALUE OF “n” FOR MANNING FORMULA FOR ILLINOIS RIVER. Based on the studies made, we have reached the conclusion that the value of V as used in the Manning Formula for Hood crest discharges in the Illinois River channel from Grafton to LaSalle is practically con¬ stant. The coefficient “n” for the overflow section is modified by vary¬ ing conditions of vegetation and topography. We have concluded also that for practical results the values should be such that a computed pro¬ file based on observed discharges will agree substantially with the ob¬ served stages when there are no levee breaks or other disturbances of channel or storage areas. COMPARISON OF VALUE OF “n” FOR MANNING FORMULA AND IvUTTER FORMULA. For flood crest discharges on the Illinois River the values of “n” have been determined, as above described, for the flood of April, 1926, with all levees holding. Typical values of the coefficient “n” for the Kutter Formula for the same flood, thru a number of reaches, represent¬ ing the range of slope and the range of hydraulic radius, have also been computed and the two values, together with the data upon which they are based, are shown in Table No. 25 which follows: For the channel section the Manning “n” is constant at .024, except for the first reach where it would have made very little difference in the computed profile if the same value had been used—in the over-bank reach the value of “n” in the Manning Formula ranges from .080 to .110. For the channel section the value of KuttePs “n” ranges from .027 to .040, the smaller values are in the reaches where the slopes are the steepest, and the larger values are in the reaches where the slopes are flatter. In the over-bank section the value of KuttePs “n” ranges from .105 to .125—where the hydraulic radius is small KuttePs “n” approxi¬ mates the value of Manning’s “n” and the greatest variation between the two is where the slope is the least and the hydraulic radius is the largest. The hydraulic radius in the channel section ranges from about 18 feet to 21 feet and in the over-bank section from about 3 feet to 9 feet. The foregoing illustrations merely indicate the greater uniformity of the derived value of the coefficient “n” for the Manning Formula as compared with that for the KuttePs Formula, when applied to the flood crest slopes and discharges for the lower Illinois River. —7 F C 98 FLOOD CONTROL REPORT. FLOOD CREST DISCHARGE PROFILES AND BACKWATER PROFILES. Flood crest discharge profiles and backwater profiles have been prepared by applying the values for “n” shown in Tables No. 22 and 24, using the method developed by H. R. Leach, Principal Assistant to Robert E. Horton, Hydraulic Engineer, described in Engineering News Record, Yol. 82, page 768. Discharge Capacity Curves for crest profile slopes have been platted for each reach of the river between Grafton and LaSalle. This method is applied by first dividing the total length of channel under consideration into reaches, each of which can be represented by a typical or average cross-section at the center of the reach, and then com¬ puting the fall required to carry given discharges thru the reach at any stage. The Manning Formula is as follows: 1.486 2/3 y 2 (1) Q = A x-x R x S in which n Q = Discharge in cu. ft. per sec. A = Area of cross section in sq. ft. n — Coefficient. Area R = Hydraulic Radius =- Wetted Perimeter Fall S - Slope =- in feet. Length 1.486 % With a given cross-section the term A x-x R is constant and n % calling this factor Kd and substituting we have (2) Q = Kd S Using the weighted average cross-section at the middle of the reach, the value of the factor Kd for overflow and channel areas can be determined separately, and combined for the total Kd value for any water surface elevation at center of reach, and a table or curve made for each reach showing the Kd values for various stages. With the discharge and stage at the center of reach given, the slope is immediately determined by equation (2) and assuming the stage at the center of reach at once fixes the fall required for any given discharge, as well as the elevation of w T ater surface at the head and foot of the reach. From this it follows that for a given discharge there is a definite relation between the stage at the foot of the reach and at the head of the reach for any assumed stage at the center of the reach. This relation can be shown by a curve for any discharge, the abscissa being the elevation at foot of reach and the ordi¬ nates the elevation at head of reach. Such a curve will be asymptotic to a straight line drawn through points of equal elevation, as with increas¬ ing depth the slope or fall thru the reach approaches zero. In this manner with any assumed discharge a curve can be drawn for each reach showing the stage relation, and since the head of any reach is the foot of the adjoining upstream reach, it follows that assuming the stage in a given reach at once fixes the stage in all other reaches above and so determines the water surface profile for the discharge assumed. ILLINOIS RIVER. 99 This method can be extended and a series of curves constructed for each reach, with a series of discharge quantities selected covering the desired range, from which by interpolation all possible profiles can be accurately determined without resort to the usual trial and error methods. The method is as follows: plot the curves of discharge and stage relation of the first reach with the stage at foot of reach on the horizontal axis and the stage at head of reach on the vertical axis. As the stage at head of Reach No. 1 is identical with the stage at foot of Reach No. 2 the axes for discharge and stage relation curves for Reach No. 2 can be reversed and the stage at foot of reach platted on the vertical axis and the stage at head of reach platted on the horizontal axis. Thus the stage at the junction of the two reaches may be read on the same ordinate on either curve. The same reasoning applies to all other reaches, and by alternating the axis in the above manner a series of discharge stage relation curves for reaches in pairs alternating on either side of the zero lines are obtained. Any initial stage and discharge at the foot of Reach No. 1 may be assumed and by tracing through the curves from the initial stage at foot of reach to the intersection of this ordinate with the discharge selected, the stage at head of reach is determined on its corresponding scale; pro¬ ceeding on this scale to an intersection with the desired discharge in Reach No. 2, the stage at head of Reach No. 2 is determined on its cor¬ responding scale. This process can be repeated from one reach to the adjoining upstream reach and the elevation of water surface at the head of each reach tabulated for use in platting the profile. An illustration of typical discharge and stage relation curves and method of using them are shown on Figure No. 35. For purpose of com¬ parison, by use of the discharge and stage relation curves, elevations were computed for profiles for the flood crests of April 1920, April 1922 and April 1927 from Grafton to Peoria. For each of these floods a table of discharges was made, using the rating diagrams as a basis and building up discharges from one gaging station to another downstream by the addition of increments from the tributary streams and areas based on U. S. Geological Survey Discharge Tables. Table No. 26 shows the magnitude of discharge determined by the above method at each gaging station, the computed stage elevation at each gaging station determined from discharge and stage relation curves, and the corresponding observed stage elevation. The computed profiles and observed profiles for the flood crests April 1920, April 1926 and April 1927, are shown on Figure No. 36 of this report. The profiles for the observed and computed high water of April 1926 from Grafton to Peoria, and April 1927, from Peoria to LaSalle are used for the determination of the coefficient of roughness “n.” These profiles show how closely the observed profile is followed by the computed profile, using the value of “n” as herein determined for the back-water computation. The computed profile for the high water of 1920 is higher than the observed profile for that year, and reflects the effect of the con¬ struction of additional levees in the Illinois Ahilley, particularly between Havana and Pekin where the Chautauqua Districts and the East Liver- TABLE NO. 26—COMPARISON OF OBSERVED AND COMPUTED STAGES FLOOD CRESTS APRIL 1920, APRIL 1922 AND APRIL 1927. 100 FLOOD CONTROL REPORT. 05 © a < 02 O t- O O o -$* lO«)lflMNM®ONNOu5l« n3 I(MCD>OCCOOC'. CiCNNCtTN o . iCCNNOONm'ttetSOC CO C. M s J 1 o ® O 1 1 © oo ooo ooooooo© bC o© ©©© ©©©©©©©© u , ©CO © CO OO CO oo OO © © CO © 00 Cw CD rj • © © © tO 05 OC OO CO 05 OO © © . ©© ©©© © 00 © © © © to © CD © 5 1 • © co © 05 co oo to © co © oo 05 O • I 05 CO CO to CO CO ^ 05 ©!>•©© 05 CD t © ^ I © © 05 © © 05 CO CO ^ to 00 © CD C3 1 o 1 1 1 05 05 © Computed stages. 1 © • P'- © © © © © t>- CO CO to © 05 05 i OQ rf © lO N t>- 05 05 CO OC © 05 © © »*— ~-05©OCOC~-05CO^tOOO© CO 1 ^ to © © © © »o to Tf 1 Tj< T}« ^ Tj< ^ Tf Tj* Tj< Tf 1 1 1 1 1 —— © ©© ©©© ©©©©©©©© p* bfi ©© ©©© ©©©©©©©© Ih . ©00 00©© 05 05 r^. © © 00 © © to to©© ©©©©oor^coo5 -4^> o • ©© ocoooo ocr^©©totototo CD CD O o t-t c 5 © • © OO © OC 00 CO CO ^ CO © CO 05 © • i © 1—1 CO CO ^ 05 © CO © 05 to pS( > § © i’—^05r^©©05C0’*f’^t0©O hr co i’^r*^’^ , ^r'^? - ^t*©©©to©©© CD C? i o i i i © 05 © Computed stages. 1 © l *— ^ t*< 05 to © CO CO 05 05 05 i T*« t'- CO © CO © CO © © 05 05 « © co © oo © ^ co © oo CO • CO CO ^ TfTf lO lO to to to to Tf 1 Tf ^ ^ ^ Tj’ Tf ^ ^ Tf< ^ ^ 1 1 1 1 1 C« < -*s cn u. O Discharge c.f.s. © © © © © ©©©©©©©© o© ©©© ©©©©©©©© © © co © to 05 oo toco 05 ^ ©©©^f^^oor^- t>- t>-!>• t'*. © © © to to © t}< ^ i © »©COtOtO©©tOCOCO©00O5O5 © . 05 i © — 05 oo co © S. CD r © 05 ir^r^oocototooo©*—^-O5©oo % tc CO iCOCOCO^tT* , ^?"0’J , iO»OtO»OtO CD C3 o" 1 1 1 1 c s ~ o co 'ts o 2 CW^MflNeiStCOONCONCn - —NNCe^OOCOMlM C o V M C3 O >i o >1 c ■£ o 3 w • ^ :o s § ILLINOIS RIVER 101 £ a-i H w a £ O z o H Oh <3 05 o Eh a-< 05 Oh Oh t —i m xn l-H s a ^05 SO e g a&2 na co> cS c2 JO az h—I aa CJ HH Eh - GO I— 1 a*5 Pi§ OC5 o 05 >21 as ad Co za a* a< tnEH ccd '7 >— 1 _ 'HH 1—4 H-* EhCG a a a 05 a H - 00 05 o o o CM CM CO rC CO CO CO CO CO p Tt< p p p p p 40 40 40 40 40 40 0 (G !—1 rf Hf Hf ^■p p p p p p p p p Hf Hf Hf Q o o CO 05 40 CO 40 CM Ol 40 CO oo CO CO CO CM o CM o CM i—l CO 40 CM oo oo CO o p l-H CO oo p CO l-H CO o • ^H CO Hf CO oo 05 o CM p CO oo oo oo 05 o l-H 1—H o CO CO CO CO CO CO Tf p p p p p Hi- 40 40 40 05 Hf Hf Hf p p p p p TF p p p p Hf Hf Hf aa o 05 CM oc oo 40 40 o 40 CO oo CM p 05 l-H Hf l < l-H o O o 00 CO p T-H 40 00 CO O CM CM 05 o 40 o 05 i—H CO 40 CO oo 05 l-H CO 40 CO 05 05 o 00 CM CO CO CO CO CO CO p p p p p p p p Hf p 40 Hf Hf Hf p p p p p p T p p p p Hf p Hf aa § o Hf CM o CO o CO oo o p oo CO t}h Ol 40 CO CO o Hf CO CO 00 p 05 05 oo 40 05 CM 05 Tf CN CO Hf oo CO 00 o _ CO 40 CO 05 y—4 CM 40 40 40 CO oo CM CO CO CO CO CO CO CO p p p —r p hhh h^ Hf Hf Hf Hf Hf Hf ^f* p p p p p p p p p p Hf Hf Hf aa o oo CO CO oo oo CO p O CM P o 40 CO o CO 05 o CO CM o p CO 00 05 CO CO o 40 CO oo 05 CM CO 40 CO oo 05 l-H CM CO CO CO CO HTf 40 CO CO co CM CM CM CO CO CO CO CO CO p p p p p p Hf Hf Hf Hf P Hf p p rr p p p p p p p p Hf Hf Hf aa 00 — oo 00 o o 40 o 40 CO 40 t-H CM CO CM 40 CO o oo 05 CM CO oo CM Tj - CO oo H^l eo OC O CO Hf cd oo o CO CO 05 o 1-H ^H hh CM CM CO Hf Hf 40 CM CM CM c«o CO CO CO CO CO CO p p p p H-T Hf Hf Hf p Hf Hf p "Tf rJH p p p p p p Hf Hf Hf d o bi tc tii rH bb -a ci O b£ -5 a tc c c3 M c o rrH <— * ci 0 hi) tb a rH r a c Ifj _; o cr? •f T3 Cu a C3 0 0* r* c3 *-H c p r* d ►—< 0 0 Kh o a o _:;_; a, M 0 c3 d 0 0* 0 ci hf ci s a d a: > 0 cr. 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ci > > a> *3 w hh d o ■£ a § s* 05 o OQ c3 fcn CD a a o d o -+.5 ra bfl d d o -4-J "E c3 ci ^d c c 3 o m JD M d d ’C *c o o O Cj PQPQfc « m pq •* CM to CM CM CO 00 0 CM CO to CO 05 0 t-H to CO i-H 0 t—H ▼“H T-H t-H CM CM CM CO CO co ^F to CO CO CO CO CO CO CO CO CO CO CO CO CO Tj* Tt* rji ■Tf o' CO 0 O T-H O O CO CO ■~F tO CO QO t-H CO 05 O CM TJH 00 CO 0 05 05 05 05 O O O 1—1 »-H H CM CO 10 to to to CO CO CO CO CO CO CO CO CO TF Tfl Tf TJH 0 CO 10 CO t-H to 05 OO CO CM OO CM to ^F CO 00 05 to OO O CO 05 CO to 0 00 00 00 05 05 05 05 0 1 -H 10 to to to to to to to to to to CO CO ^ Tt< Tt< Tt< 10 00 0 CM CM d 5 00 CO 05 CO to CO 00 CM >ot- 05 »-H to CO CM 0 to to to to to CO CO 00 05 to to to to to to to ^ to to to to to Tf« Tf< 0 01 05 CM CM 0 10 0 05 00 CO CM cn a B cS W cS a o u u o CO 'd c3 a g _o « 01 tl u o o o £ 52 ; * c o • r—> -*-> c3 o o > >> 0) > <1 43 'S3 w .2 ’EJ o o> Oh > Oj to O S 0) a o 0) <3 43 43 ■hj +2 O O 0 o 43 43 ou 13 o o rt >> C 0> a <3 44 ci hJ C c3 it co 01 44 c3 h4 a <3 G G a> w a <3 c G <3 a >> a> > bfl _G ‘C a CO 0> to •3-3 Sco 0) C3 Ph>J C .2 c3 -*-> m O 0 0 0 O 0 0 0 05 »—H + 4 " + + CM OO OO O T-H to ^F 05 CO CO O CM to OO O •rF co co 0 CO CO 05 05 CO CO 00 00 OO 05 05 05 05 0 O O 0 0 T-H T“H t-H T-H T-^ y—* T-H t-H a § o tf CO 00 CO 05 CO CM CO tO CO OO 104 FLOOD CONTROL REPORT. pool District were not completed in 1920. The computed profile for the April 1927 high water is slightly higher than the observed from Kampsville to Bath, and from Bath to Peoria is considerably higher. A number of levee districts were open and receiving storage between Kampsville and Bath. Between Bath and Peoria the water was flowing thru the Chautauqua District and East Liverpool District, and the pro¬ files show clearly the effect on flood stage of closing the levees in these districts. Back-water flood crest discharge elevations for profiles were com¬ puted using the discharge stage relation curves shown as typical dis¬ charge on Figure No. 37, as above described, for discharges of— 50,000 to 170,000 from Grafton to Meredosia. 50,000 to 160,000 from Meredosia to Beardstown. 50,000 to 140,000 from Beardstown to Bath. 50,000 to 130,000 from Bath to Havana. 50,000 to 120,000 from Havana to Copperas Creek. 40,000 to 100,000 from Copperas Creek to Peoria. 30,000 to 90.000 from Peoria to LaSalle. All of the above elevations were computed from a normal flood stage in the Mississippi River corresponding to a normal flood crest in the Illinois River, without apparent back-water effect, and are shown for the end of each reach in Table No. 27. On Figure No. 37 “Normal Flood Crest Profiles” are also shown back-water flood crest profiles, as follows: 1. The computed October 1926 flood crest discharge entering the Mississippi River at the elevation of October 1926 high water, with all levees holding. 2. The computed October 1926 flood crest discharge entering the Mississippi River at the elevation of the 1844 high water, with all levees holding. 3. For a discharge 20,000 c. f s. greater than the computed October 1926 flood crest entering the Mississippi River at the 1844 high water, with all levees holding. The flood stage of 1844 was higher at LaSalle than the back-water computations for the maximum flood as computed for present levees. The valley from Peoria to LaSalle has a much greater carrying capacity than in 1844, due to the deadening of timber and better flowage con¬ ditions. COMPARISON OF DISCHARGE RATING CURVES AND DIAGRAMS-PEORIA—• HAVANA-—BEARDSTOWN-PEARL. The discharge rating curves made by the IT. S. Engineers, and dis¬ charge rating curves made by the U. S. Geological Survey at Peoria, Havana and Beardstown from discharge measurements made by them, respectively, since 1920 are shown on Figures, Nos. 38 and 39, with the discharge rating diagrams developed in the study for this report. These discharge rating diagrams are based upon the discharge computations for discharge, stage and slope at those stations, with all levees now constructed sufficiently high and holding. At Beardstown the rating ILLINOIS RIVER. 105 curves of the U. S. Engineers, the U. S. Geological Survey and our computed normal rating curve for flood crest, are in substantial agree¬ ment up to elevation 452, which is about a 25-f'oot stage on the Beards- town gage. Above that stage the U. S. Engineers and U. S. Geological Survey have no discharge measurements and their curves if projected would show discharges much in excess of the discharges by the flood crest normal rating curve with all levees holding. The rating diagram and normal rating curve for Pearl are those developed in the study for this report. At Havana there is a very marked divergence between the U. S. Engineers, the U. S. Geological Survey and our flood crest normal rating curves. This is evidently due to the fact that the flow passing Havana at the time the discharge measurements were made was greatly modified by the Spoon River in-flow and levee breaks, as all high stage discharge measurements were made either in 1922, 1926 or 1927. At Peoria the II. S. Engineers rating curve and our flood crest normal rating curve are in close agreement, but the U. S. Geological Survey discharge rating curve shows a much lower rate of discharge. The dis¬ agreement in these rating curves is doubtless due in large part to the levees breaking and the modification of the fall from Peoria to Pekin resulting therefrom. The flood crest normal rating curves and the flood crest slope discharge diagrams shown on these two figures (Nos. 38 and 39) are developed from the normal flood crest back-water profiles shown on Figure No. 37 in this report. MAXIMUM ELOOD DISCHARGES. The flood of October 1926, represents the maximum inflow entering the Illinois Valley at Beardstown of which we have any definite record. The flood of 1904 probably represents the greatest inflow at Peoria. There is practically no information regarding the flood of 1844, except the high water profile determined from high water marks identified by the U. S. Engineers in their survey (1902 to 1904) for the report on the 14-foot Waterway, H. D. 263, Fifty-ninth Congress, First Session. The earlier reports of the surveys and investigations of the Illinois River show that the overflowed valley lands were covered with a dense growth of timber and vines. A large part of the timber and brush which was growing in the lower Illinois Valley, especially above Beardstown, has been killed by the higher Summer river stages which have prevailed since the opening of the Chicago Sanitary and Ship Canal. The flood carrying capacity of the overflowed area has been increased from 10 per cent to 20 per cent by deadening of the timber and brush, previously growing on large areas or overflowed land. Alvord and Burdick esti¬ mated the flood discharge of 1844 as 10 per cent greater than that of 1904 at Peoria. The recent studies of the flood carrying capacity of the Illinois Valley, taking into account the ^conditions of vegetation, and the fact that for the very flat slopes winch exist between Peoria and LaSalle the capacity computed by Kutters Formula is greater than that computed by Mannings Formula, we have reached the conclusion that the maximum 106 FLOOD CONTROL REPORT. discharge at Peoria for the 1904 flood did not exceed 75,000 c. f. s. and probably was nearer 70,000 c. f. s. These conclusions are supported by the following: 1. The discharge rating curve for Peoria, based upon measure¬ ments made by the author of this report in 1900, indicate a discharge for the 1904 flood stage of 75,000 c. f. s. 2. A back-water computation from Peoria to Peru, using the factors that apply to the present condition of the channel and over¬ flowed area with 75,000 c. f. s. at Peoria, and a reduction in the quantity up-stream for inflow of tributaries, produced a profile which corresponds almost precisely with the high water profile of 1904. 3. A back-water computation for 90,000 c. f. s., with corresponding reductions as we proceed up-stream and starting from Peoria at the stage of 1904 high water, produced a high water profile which is 0.8 foot above the observed stage of 1904 at Henry—no available gage read¬ ings at Peru. We have not been able to get the back-water computations from Peru to LaSalle to check against the observed slopes, due no doubt to unknown obstructions and factors of the area of the channel and over¬ flow. 4. A considerable portion of the overflowed area in the valley be¬ tween Peoria and Peru was covered in 1904 with a dense growth of timber which is now dead and has disappeared. The estimated flood discharge for the October 1926 flood, upon which back-water computations have been based, assuming that all exist¬ ing levees were holding, is as follows: Grafton to Kampsville. 120,000 c. f. s. Kampsville to Pearl. 117,000 c. f. s. Pearl to Crooked Creek. 115,000 c. f. s. Crooked Creek to Beardstown. 110,000 c. f. s. Beardstown to Havana. 72,000 c. f. s. Havana to Pekin. 66,000 c. f. s. Pekin to Peoria. 60,000 c. f. s. Peoria to Chillicothe. 59,000 c. f. s. Chillicothe to Henry. 58,000 c. f. s. Henry to Hennepin. ‘ 56,000 c. f. s. Hennepin to LaSalle. 55,000 c. f. s. The October 1926 flood represents a discharge at Peoria of 59.000 c. f. s., which is about 10,000 less than our present estimated flood dis¬ charge of 1904. In 1926 the Sangamon River at flood-crest is estimated to have been delivering 38,000 c. f. s. at Beardstown, but the Alvord and Burdick estimates of the Sangamon contribution to the maximum dis¬ charge of the 1904 flood is 15,000 c. f. s. From a consideration of all the conditions of the tributaries and their possible contributions to the flood stage at crest, we have reached the conclusion that the maximum flood discharge, with all levees holding, from Beardstown to Grafton, may be 20,000 c. f. s. in excess of the estimated discharge of 1926. We have also reached the conclusion that the maximum discharge from Beardstown to LaSalle may be as much as 20,000 c. f. s. in excess of that of 1926. In other words, the flood discharge as estimated for 1926 may be exceeded thruout the entire length of the lower river by 20,000 c. f. s. additional. This would represent an average discharge of about 30 per ILLINOIS RIVER. 107 cent in excess of that of 1926 for the river above Beardstown, and about 18 per cent in excess of that of 1926 below Beardstown. FLOOD FLOW OVER VALLEY LAND. Before levees were built a very large portion of the flow of major floods passed down-stream over the wide valley. Between Beardstown and Hardin the valley was from two to four miles wide and more than 95 per cent of this area has been leveed. Approximately 50 per cent of the dis¬ charge of a major flood at crest passed over the valley. Similar condi¬ tions prevail between Pekin and Havana, where about 75 per cent of the land has been leveed. With levees holding the water must rise high enough in the channel and over the remaining narrow floodway between the river channel and the levees or foothills to compensate for this re¬ duced floodway area. CLEARED FLOODWAYS. All reports upon the floods of the Illinois River, which refer to the carrying capacity of the channel, refer to the effect of timber, brush and other vegetation upon the water carrying capacity of the over¬ flowed area. In general terms it has been found that a river channel which is free from vegetation has a carrying capacity of from two to six times as much as a floodway of equal depth and width grown up with grass, weeds, brush or timber. The ratio of the carrying capacity of a floodway to that of a clear channel depends upon the relative density of the vegetation. Many estimates have been made for the carrying ca¬ pacity of a floodway clear of vegetation and kept as a cleared floodway at flood time. The greater number of floods occur in the Spring months, but the most disastrous flood on the Illinois River occurred in October when all timber and brush growth were covered with leaves, and weeds and grass and were of maximum proportions, literally cutting off at the beginning of the flood, and in many instances until the flood crest had actually passed, from one-half to three-fourths of the carrying capacity of the overflowed or floodway areas. The great expense which would be incurred from year to year to maintain effectively cleared floodways for carrying floods occurring at irregular intervals has not been accomplished and probably will not be readily provided for by drainage districts, because of the apparent wast¬ ing of money thus expended covering many years when no large floods occurs. The land-owners in the levee districts are hard pressed with taxes and are properly jealous of unnecessary expenditures, and main¬ taining a cleared floodway does and would appear, to them, to be un¬ warranted. Long years of contact and experience in maintaining levees leads to the conclusion that it is not safe to anticipate that floodways will be maintained clear of timber, except in specially favored areas where the land in the floodway is overflowed so seldom that it can be cultivated at a profit. Under the control of the State, or a political sub-division of the State covering the entire valley, charged with the responsibility, floodways might be maintained in much more efficient condition. For the low lands alternate flooding and draining might be provided for so 108 FLOOD CONTROL REPORT. that during the early part of the season the land might be flooded and prevent the growth of land plants, and drained during the latter part of the season when the land plants would not naturally thrive, but during which time the aquatic plant growth would perish. The two methods above mentioned might be combined in such a manner as to give a very much larger efficiency to the floodways at little cost, but keeping the vegetation down by seasonal cutting as the only other alternative must not be relied upon. In view of these conditions the carrying capacity of any floodwav must usually be predicated upon the condition and growth of vegetation which nature will produce. SILT ACCUMULATION IN THE FLOOD WAY. The tributarv streams all carry a considerable amount of silt, a large part of which is deposited along the banks of the channels and on the land overflowed where the water from the tributaries enters the Illinois River. This process of building up the banks is continuous. Where the smaller tributaries enter the valley there is a perceptible filling of considerable magnitude, but the major portion of the silt brought down by these streams is deposited soon after it enters the valley and only a very small part is deposited along the main stream. The silting problem is, therefore, primarily of local interest to the land adjacent to the outlets of the smaller streams and the valley immediately near the foot-hills. The capacitv of the floodwav for the main stream will not j . %j be vitally affected by sediment. DAMAGES TO FLOODED DISTRICTS. About one-half of the leveed area was flooded in 1926 and the damage to crops and property for this one overflow has been estimated at $6,000,000 which is more than enough to pay for the cost of raising the levees as much as the increased stage would have been. The damages due to the interference with the program of farming by flooding, such as when a levee breaks with the overflow continuing for several months (and, as in 1926 and 1927, an average of more than a year), cannot be fully measured by the destruction of crops, the cost of repairing broken levees, cleaning out ditches, repairing and restoring buildings and roads, but includes also an indeterminable depreciation, due to the discourage¬ ment of those who are using or would use the lands. It is practically certain that owners and tenants would not willingly subject themselves to the hazard in levee districts which are to be used for emergency flood crest storage, and that they would abandon the land if such a program were to be carried out, unless very definite arrangements were provided by the State for full compensation for damages in case of flooding. In view of the increasing demand for fish and game preserves along the Illinois River, it might become a profitable enterprise to convert some of the existing levee districts, or to construct levees around some of the remaining open areas to be used for flood crest storage without great damage to the property as fish and game preserves. It would doubtless ILLINOIS RIVER. 109 be necessary for the State, or some agency to be created by the State, to take over these lands and provide the necessary funds for their main¬ tenance, because it is not probable that private enterprise could be relied upon to carry on a development of this kind which would be effective for flood control purposes. FLOOD CONTROL METHODS. The low lands in the Illinois River Valiev may be protected from floods by two general methods: First—Improvement of the River Channel. Second—Storage of flood water: 1. Improvement of the river channel may include: (1) Raising the levee heights. (2) Excavation of channel. (3) Widening of floodway by setting levees back. (4) Keeping the overflowed area free of vegetation that would obstruct the flow. 2. Storage may be provided by: (1) Reservoirs or detention basins in the valleys of the tributary streams. (2) Storage areas in levee districts or behind levees specially constructed for flood crest storage in the Illinois Valley. (3) Control of the diversion of water from Lake Michigan dur¬ ing flood periods. The construction of levees and increasing the levee heights to pre¬ vent overflow produces higher flood stages and subjects additional lands to overflow, thus extending the area menaced by floods. The other methods of flood control all tend to reduce the stages for any given flood flow, but some of them do not produce results in proportion to their cost. Channel excavation, while necessary and useful for low water navigation, is not a practicable method for increasing flood carrying capacity of streams of the magnitude of the Illinois River. Widening the floodway by setting levees back has been investigated and shows that a substantial lowering of the river can be accomplished from Pearl to LaSalle at a cost considerably less than the cost of raising levees sufficiently to take care of an equal flood-flow. Keeping the over-banks portion of the channel clear of vegetation has a much greater value than is generally recognized and, for the purpose of the estimates in this investigation, the areas which lie between the present levees and the proposed location for set-back levees, which is now under cultivation, is expected to be maintained free from timber, brush and growth of large annual weeds by cultivation, or by alternate flooding and drying, so as to give an effective carrying capacity of about double that of the ordinary over-flowed area with natural growth of vegetation. Storage or detention basins on tributary streams to be effective for flood control in the Illinois River would require a large number of such reservoirs. This would necessitate the appropriation of valuable land, much of which is in a high state of cultivation in the valleys of the tribu- 110 FLOOD CONTROL REPORT. tary streams and, nnder present conditions, cannot be relied upon for flood control in the Illinois River. With the increase of population on the Illinois watershed the municipal and industrial demands for water supply will require storage reservoirs on the tributaries, and these may be so designed as to serve the double purpose of providing water supply and flood control, which could be reflected in lower flood stages in the Illinois River. Flood crest storage in the levee districts in the Illinois Valley may be used to hold down peak-flood stages. The effect of this storage is very well shown by the breaking of levees in the floods of 1922 and 1926. The computations show that if the levees had not broken in 1926 the river stage would have been higher through the central portion of the lower valley, as follows: At Peoria .1.33 ft. At Meredosia .2.56 ft. At Copperas Creek.1.92 ft. At Valley City.2.20 ft. At Liverpool.1.93 ft. At Pearl .2.89 ft. At Havana .1.73 ft. At Kampsville .1.97 ft. At Beardstown .1.79 ft. DISCHARGE AND STORAGE RELATIONS. The general equation for Discharge and Storage Relation is: Inflow == Outflow Storage When a stream is rising the inflow is greater than the outflow by the amount of the storage represented by the rise, and when falling the inflow is less than the outflow by an amount represented by the fall. The area of the water surface, therefore, becomes a controlling factor in stream flow. As the flood crest proceeds down-stream the water is falling in the upper and rising in the lower reaches, and the problem of esti¬ mating discharge becomes further complicated when overflow storage areas and the floodway carrying capacity are both modified by levee building and by breaks in levees. The effect of levees on the stage of the river is shown by the greater increase in stage in the central and lower portion of the valley where the overflow areas have been most reduced. Discharge measurements along the main stream and of the tribu¬ taries from which reliable discharge and rating curves or diagrams may be made, daily or semi-daily river stages at control points, and accurate surveys of the river channel and overflow areas furnish the data needed. The discharge measurements of the Illinois River made during the last thirty years disclose that its flood carrying capacity for any high water stage is much less than before levees were built. It is necessary to know the inflow, the storage area available and the discharge capacity at the outfllow point for computing river stages based upon inflow, outflow and storage. Outflow points must be chosen where discharge rating curves or discharge rating diagrams are available. The river valley should be divided into reaches thru which the normal flood crest would pass within a one day period to simplify the storage compu¬ tations. A working formula has been developed for computing the daily change in stage, without resorting to approximating the ratios of the inflow which would be accounted for as storage and discharge. The • formula is as follows: ILLINOIS RIVER. Ill Q — Q h— in which— A + h = the rise (or fall) in feet or stage for one day. Qs = the inflow in c. f. s. days for one day, or the average rate of inflow in c. f. s. Q x = outflow in c. f. s. days for one day, at the rate of flow at the beginning of the day. A = the total storage area in acres divided by 1.98 which is equivalent to c. f. s. days storage one foot deep. q = the increase of discharge in c. f. s. for one foot of rise above the the stage at the beginning of the day, which is the rate of in¬ crease in discharge for stage at the beginning of the day. The foregoing formula reduced to a rule would be as follows: From the total inflow for a day subtract an amount equal to the outflow for a day at the rate at the beginning of the day; divide the dierence by the sum of the storage for one foot of depth over the area plus one-half of the increase in discharge for one foot of rise at the stage at the be¬ ginning of the day; the quotient will be the increase or decrease in stage in feet. Beginning at the up-stream outflow station and using inflow quantities during the progress of a flood, daily stage readings may be computed for any given condition of inflow and storage. Considering the outflow as the inflow of the next reach down stream and adding the tributary inflow, the stage may be computed for the next gaging station, and in this order develop profiles of daily stages. By using discharge rating diagrams, which show stage-slope-dis¬ charge relations, adjustments may be made in the daily computed flood profiles based upon the inflow, outflow and storage equation. Computations have been made for the stages that would have oc¬ curred at Beardstown and Havana in the October flood of 1926 if the levees had held, using the inflow, outflow and storage relations. From these computations the rate of discharge from day to day which would have occurred if the levees had held was determined. Back-water compu¬ tations for flood crest profiles check closely the stage for 1926 flood, with all levees holding, that was found by the inflow and outflow computations. FLOOD HEIGHTS REDUCED BY SET-BACK LEVEES. The levees constructed on both banks of the Illinois Biver from Beardstown to Pearl are from 1,100 to 2,000 feet apart. The river stages at Beardstown and vicinity have been increased to a greater extent than at any other portion of the Illinois valley. Some method of reducing flood stages in this reach of the river and lessening the hazard of break¬ ing levees is of greatest importance. A study has been made to deter¬ mine to what extent the flood stages can be lowered by setting levees back wherever it is economically possible, thereby increasing the floodway carrying capacity. There are long lakes parallelling the river back of the levees in a number of these levee districts, and the plan for levee set¬ backs includes construction of new levees behind the lakes in these dis- 112 FLOOD CONTROL REPORT. tricts, so as to get not only the benefit of widening, but also the depth for increasing the carrying capacity of the floodway thru levee set-backs. The studies disclose that the high water stages can be reduced, depending upon the magnitude of the flood, at Beardstown from two feet to nearly three feet, at Peoria about one and one-half feet., and at LaSalle about one foot, by setting the levees back thru a portion of the following dis¬ tricts, viz—Big Swan, Big Prairie, Scott County, South Beardstown, Valley City and Cole Creek, and leaving the Chautauqua District open. No estimates have been made for setting levees back below the Big Swan District, because the back-water from the Mississippi Eiver is the con¬ trolling factor in levee heights from Grafton to the vicinity of Pearl, and the Big Swan District is the first that appears to offer an economical location for levee set-back. The position of the proposed set-back levees and the areas which would be included in the floodway are shown on map. Figure No. 40. Computed high water profiles for flood stages, with all levees hold¬ ing in their present positions, and also with the levees set-back, are shown on Figure No. 41. These profiles are computed for two flood quantities, viz— 1. Flood discharge equal to the flood of 1926 when confined between levees and entering the Mississippi Biver at the 1844 flood stage. 2. Flood discharge 20,000 c. f. s. greater than the flood discharge of 1926 entering the Mississippi Biver at the 1844 flood stage. On this drawing, Figure No. 41, are shown the following profiles: (1) Profile A represents the observed river stages for the October 1926 flood. (2) Profile B x represents the computed flood crest profile for a discharge equal to that of October 1926, with all levees hold¬ ing. (3) Profile B 2 for the same conditions as B 1? except with the levees set back, as shown on Figure No. 40 and with the Chautauqua District open. (4) Profile Cj is for the same discharge as Profile B 1? entering the Mississippi Biver at the 1844 flood stage. (5) Profile C 2 is for the same condition as C x , except with the levees set back, as shown on Figure No. 40 and with the Chautauqua District open. (6) Profile D x is for a discharge 20,000 c. f. s. greater than that of 1926, with all levees holding, entering the Mississippi Biver at the 1844 flood stage. (7) Profile D 2 is for the same condition as D x , except with levees set back, as shown on Figure No. 40 and with the Chautauqua District open. All of the foregoing computations are based upon the existing levees holding and no other levees (except set-backs) constructed in the Illinois Valley. Table No. 28 contains flood stage elevations for effect of setting levees back, as shown on profile, Figure No. 41. TABLE NO. 28—FLOOD STAGES WITH AND WITHOUT LEVEES SET BACK. 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CO OO 05 O CO CO O 05 O 05 05 ^ Tf T)1 N 05 05 C5 t-H CO 05 CO CO 'Tf CO oo oo co 05 o T-H CO 05 tO CO tO 05 ^ 05 o o to o 05 t-H 05 05 CO 05 t-H 05 £ O Hi «-4-4 Hi Q) > s CJ . .r-i rj 9 £ g > Mtf tfHOtOOOO N 05 Tf C 5 th OO C5 05 N CO O CO CO O CO t-H CO co 05 to 05 ^ -Tji Hf to t-H 05 co th CO 05 CO ~H CO 05 o o t^ t-H 00 05 CO 05 C 0 Hft 0 C 0 N 00 05 O-H 05 C 0 , ft 0 ON 0005 O’H 05 M th t-H t-H t-h t-H t-H t-H t-H 05 05 05 05 05 05 05 05 05 05 CO CO CO CO ILLINOIS RIVER 117 OcO^ON^OS OO O^COON^C^O CO WN0OOOh^iO »-H t-H Cl 1-H NC0 03N«DC0O»0 1 1 IO O 1.0 lO ^ o Tf o 1 —H t—H i-H ^H t-H ^H t-H 1 1 1 1 1 1 1 1 ^ifOHNOiolO N- 05 ooiHijioiNino) T-H *-H »—H i-H CQ Cl Cl 1 CO <0 05 CO lO O 1 t- 05 ^ COiOfO-^OO IN 05 (O CO 03 TP rf N 1 OO Cl i i l i l l l T-H l H(M00 03N(N 1 05 1 1 05 OO N- »C N- C5 1 N- 1 i-H ^H ^H t— 1 i-H i-H 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 CO’HCOHON 1 lO T-H O 03 N »C (M 1 OO OO lO ^ N rH irj i lO 05 »-H i —h t-H | 1 1 1 1 1 1 CO (N f O 03 CO (M iO O ONtPtPC5C0030 *o (N(NCOtPcOO^(M 05 CO TPrHOrHOONOO) 05 NCO(NNNO(NO Cl 05 i OO M o TP X IN CO ^PONCOOOOl i OO -*“-< i ■ i | 1 1 1 1 1 1 1 1 1 i I I i O i i | 1 1 l I Cl I i 1 i i i i O i i i i i i i i i , >» ; ; ; 1 J ! 1 x ! ! i 1 o 3 i >>”0 O' F 3 f a> G ; _ 888 17.2 550 1,668 17.0 1,097 38 Fairbanks-Keach_ ___ 1,287 18.8 582 2,220 15.7 1,350 39 Eldred.. _ .. .. 1,668 20.1 921 2,514 17.2 1,352 40 Spankey_ 603 15.4 478 41 Nutwood_ __ 1,667 18.4 959 966 17.0 558 Total_ _ 31,918 17,626 22,508 13,797 * Set-back levees. Details of the levee heights were not available for a number of the districts listed in the foregoing tables where the quantities are omitted. The approximate amount of enlargement for the levees in these districts was estimated at the average height of all levees scheduled in the Tables 29 to 32. The following Table No. 33 is a resume of the dimensions and volumes of levees and Table No. 34 contains estimates of cost of en¬ largement and set-backs as shown. ILLINOIS RIVER. 121 TABLE NO. 33—RESUME OF LEVEE ENLARGEMENT AND LEVEE SET-BACKS FROM GRAFTON TO PEORIA. 1 . 2 . 3 . 4 . 5 . Present levees— .1 Length of levees in feet__ Length of levees in miles____ .2 Fill in cubic yards__ .3 Average height of levees, feet_____ Levees 3 feet above high water profile for 1926 flood discharge all levees holding and entering Mississippi River at 1844 flood stage— .1 Total enlarged levees, cubic yards_ .2 Average height of levees, feet___ .3 Enlargement, cubic yards___ Levees 3 feet above high water profile for 1926 flood discharge all levees holding and entering Mississippi River at 1844 flood stage and with levee setbacks as shown in Figure No. 40. .1 Length of set-back in feet_ Length of set-back in miles___ .2 Length of levees used and set-backs in feet__ Length of levees used and set-backs in miles___ .3 Enlarged levees used, cubic yards...... .4 Set-back levees, cubic yards_ .5 Total enlarged set-back levees_____ .6 Average height of levees, feet_ .7 Enlargement and set-backs, cubic yards... Levees 3 feet above high water profile for discharge 20,000 c.f.s. greater than 1926 flood discharge from Grafton to LaSalle, all lev¬ ees holding and entering Mississippi River at 1844 flood stage— .1 Length of levees in feet___ Length of levees in miles___ .2 Total enlarged levees, cubic yards..... .3 Average height of levees, feet.._ .4 Enlargement, cubic yards___ Levees 3 feet above high water profile for discharge 20,000 c.f.s. greater than 1926 flood discharge from Grafton to LaSalle, all lev¬ ees holding and entering Mississippi River at 1844 flood stage and with levees set-backs as shown in Figure No. 40. .1 Length of set-back in feet_ Length of set-back in miles_____ .2 Length of levees used and set-backs in feet... Length of levees used and set-backs in miles___ .3 Enlarged levees used, cubic yards_ .4 Set-back levees, cubic yards_ River¬ front. Returns. Total. 714,600 695,400 1,410,000 135.5 131.8 267.3 17,682,000 9,429,000 27,111,000 15.8 11.5 13.8 31,981,000 22,197,000 54,178,000 18.8 15.7 17.3 14,299,000 12,768,000 27,067,000 108.800 20.6 686,200 675,300 136,500 130 128 258 22,043,000 4,724,000 26,767,000 18,529,000 45,296,000 17.4 14.5 16.0 12,475,000 9,816,000 22,291,000 714,600 695,400 1,410,000 135.5 131.8 267.3 38,465,000 27,566,000 66,031,000 20.7 17.6 19.2 20,783,000 18,137,000 38,920,000 108,800 20.6 686,200 675,300 1,361,500 130 128 258 26,507,000 5,411,000 .5 Total enlarged and set-back levees, feet_ .6 Average height of levees_ .7 Enlargement and set-backs, cubic yards. 31,918,000 19.2 17,626,000 22,508,000 16.1 13,797,000 54,426,000 17.7 31,423,000 For construction estimates, surveys and detail studies of location for set-back levees will be necessary, but the estimates herein are rela¬ tively correct. 122 FLOOD CONTROL REPORT. TABLE NO. 34—ESTIMATED COST FOR THE ENLARGEMENT OF LEVEES ON THE PRESENT LOCATIONS AND FOR THE ENLARGEMENT OF LEVEES USED WITH SET¬ BACK LEVEES. 1. Levees 3 feet above high water profile for 1926 flood dis¬ charge all levees holding and entering Mississippi River at 1844 flood stage— Levee enlargement as per table__27,667,000 cubic yards Levee enlargement districts not detailed. 3,225,000 30,892,000 cubic yards at SO.25 $7,723,000 Right-of-way 267.0 miles at S2,500____ 667,000 Estimated cost____ $8,390,000 2. Levees 3 feet above high water profile for 1926 flood dis¬ charge all levees holding and entering Mississippi River at 1844 flood stage and with levee set-backs as shown in Figure No. 40- Levee enlargement and set-backs as per table_22,291,000 cubic yards Levee enlargement districts not detailed.. 2,404,000 24,695,000 cubic yards at $0.25 $6,174,000 Right-of-way 258 miles at $2,500...$ 640,000 7,600 acres setback area at $200...__ 1,520,000 -- 2,160,000 Moving pump stations and changing ditches_____ 150,000 Estimated cost_____ $8,484,000 3. Levees 3 feet above high water profile for discharge 20,000 c.f.s. greater than 1926 flood discharge from Grafton to LaSalle all levees holding and entering Mississippi River at 1844 flood stage— Levee enlargement as per table_38,920,000 cubic yards Levee enlargement districts not detailed_ 4,579,000 43,499,000 cubic yards at $0.25 $10,875,000 Right-of-way 267 miles at $2,500____ 667,000 Estimated cost_____.$11,542,000 4. Levees 3 feet above high water profile for discharge 20,000 c.f.s. greater than 1926 flood discharge from Grafton to LaSalle all levees holding and entering Mississippi River at 1844 flood stage and with levee set-backs as shown in Figure No. 40. Levee enlargement and set-backs as per table_31,423,000 cubic yards Levee enlargement districts not detailed.. 3,499,000 34,922,000 cubic yards at $0.25 $8,730,000 Right-of-way 258 miles at $2,500..$ 640,000 7,600 acres set-back area at $200...__ 1,520,000 - $2,160,000 Moving pump stations and changing ditches___ 150,000 Estimated cost___$11,040,000 LEVEE ENLARGEMENT SPECIFICATIONS. The plans and specifications for the strengthening and enlargement of the levees should provide a greater factor of safety in cross-section as well as greater height. Most of the levees along the Illinois River have what may be regarded as a minimum workable cross-section with top wddths of from two feet to six feet and combined side slopes ranging from four to five horizontal to one vertical. One or more levees have been constructed with combined side slopes of six horizontal to one vertical. Besides greater volume for resistance to pressure and seepage, it is important that the levees should be constructed with slopes flat enough so that team work may be done in cutting the vegetation to keep the levees properly surfaced and sodded. This has not been practicable with most of the levees left in the rough as constructed by dredges. Experience in levee maintenance shows that a side slope of three horizon¬ tal to one vertical is practically the steepest that can be traveled with teams or with tractors suitable for keeping the levee in condition. The type of soil usually found along the hanks of the Illinois River is ver} ILLINOIS RIVER. 123 effective in resisting seepage, otherwise there would have been many more failures of the Illinois River levees. For estimating purposes and as a recommendation, we have used minimum dimensions for the cross- sections of levees, as follows: Top width eight feet, side slopes on both sides of three horizontal to one vertical,* with banquettes at all sloughs and low places where levees are more than 18 feet high. The levees should be surfaced and seeded to grass and either grazed with cattle, horses or sheep so as to keep the vegetation down, or clipped once or twice a year with a mowing machine. For protection of levees on the water side from erosion by wave action it will be necessary to maintain a growth of willows or other trees in front of the levee. Where the river bank is not high enough to sus¬ tain a natural growth of timber sufficient to protect the levee, a special berm should be constructed on the river side of the levee and planted with willows, which could be cut back from time to time so as to keep the growth of willows a few feet higher than the top of the levee and thick enough on a narrow strip or berm to protect the levee from erosion by wave action. CHAUTAUQUA DRAINAGE DISTRICT LEFT OPEN. The computations for high water profiles with levee set-backs con¬ template leaving the Chautauqua Drainage District open for flow and storage. If the Chautauqua District levee should be reconstructed high enough and strong enough to hold, the flood stages would be one and one-half feet higher at the head of the district just above Liverpool, one foot higher at Kingston and 0.75 of a foot higher at Peoria with a corresponding increase in height, Peoria to LaSalle. With this show¬ ing the lowering of water stage by leaving the Chautauqua District open, no separate estimate has been made of comparison of cost of the land in the Chautauqua District, as compared with the cost of raising levees an amount corresponding to the increased river stages which would be produced by rebuilding these levees. CITIES ALONG THE ILLINOIS RIVER. The City of Beardstown was invaded by floods in 1922, 1926 and 1927. After the flood of 1922 the Illinois Legislature made an ap¬ propriation for the construction of flood protection works, but the State and City authorities were unable to agree as to the plan until after the flood of 1926. The flood control works consist of a concrete “seawall” along the river front in the business portion of the city, and an earth levee from the ends of the “seawall,” around both sides of the city back to the high land above overflow. The top of the “seawall” is at elevation 455 Memphis Datum, which is 27.75 feet on the Illinois River gage at Beardstown. Provision has also been made for flash boards two feet high on the top of the wall. The earth levee is constructed to a grade four feet above the top of the wall, or two feet above the flash boards. * Note : By Division of Waterways— It is believed that no one standard levee section can be selected as suitable for all locations along the Illinois River. The section used for construction in any location should be based on height of levee, kind of soil and exposure to wave action. 124 FLOOD CONTROL REPORT. The high water of 1926 was 26.36 feet on the river gage at Beards¬ town, which is about 1.4 feet below the top of the “seawall.” The flood height for 1926, with all levees holding, would have been elevation 455.4 Memphis Datum, or .4 of a foot above the concrete wall, and 1.6 feet below the top of the flash boards on the “seawalls.” With all levees holding and with a flood 20,000 c. f. s. greater than that of 1926 entering the Mississippi River at the 1844 flood stage, the river would be 5.2 feet higher than in 1926, which is elevation 458.8 Memphis Datum, or .2 of a foot below the top of the Beardstown earth levee and 1.8 feet above the top of the flash boards for the “seawall.” With levees set back as proposed, the river stage for the same maximum flood would be at elevation 456.13 Memphis Datum, which is .87 of a foot below the top of the flash boards. At Peoria, Water street and the railroad tracks in the vicinity of the Rock Island depot were flooded in 1926. The estimated maximum flood height at Peoria, with all levees holding, would be 4.90 feet higher than the observed stage of 1926, or, with the levees set back as proposed, 3.18 feet higher than the stage of 1926. Smaller toAvns along the Illinois River, Browning, Frederick, Meredosia, Valley City and Naples were all flooded in 1922, 1926 and 1927. Meredosia and Naples have increased their levee protection, but with increased flood stages these smaller towns will be flooded to greater depth and will require enlargement and raising of their levees. In the reach of the river between Peoria and Pekin, there is a con¬ siderable amount of overflowed land which has not been reclaimed. The industrial development in this locality points to the early demand for re¬ claiming of a considerable portion of this area for manufacturing sites. Computations have been made of the effect of leveeing the Illinois River on both sides, from Peoria to Pekin, with an allowance of 1,500 feet be¬ tween levees, in accordance with the present rule of the U. S. Army Engineers for harbor lines, which shows that if these levees be constructed the flood stage at Peoria would be increased by reason thereof 1.30 feet, which is in excess of the estimated flood stages as shown in the tables and profiles in this report. THE VALLEY DISTRICTS NEAR BEARDSTOWN. East of Beardstown is an area of about 10,000 acres of second bot¬ tom land lying at an elevation between the 20-foot and 25-foot marks on the river gauge at Beardstown. This land has been for many years in a high state of cultivation and was not overflowed prior to construction of the levees, but subjected to frequent and disastrous flooding since. Levees of moderate height would protect these lands from overflow, but would also reduce the available storage between Havana and Beardstown about 25 per cent, equal to an increase discharge of 2,500 c. f. s. at Beardstown when the river is rising at the rate of 0.5 foot per day. ILLINOIS RIVER 125 ILLINOIS RIVER. 127 128 FLOOD CONTROL REPORT. ILLINOIS RIVER. 129 —9 F C 130 FLOOD CONTROL RErORT. ILLINOIS RIVER. 131 U * < _J o< z o z £ KEOKUK 132 FLOOD CONTROL REPORT. Z < cr < i CD O o < ~) ILLINOIS RIVER. 133 134 FLOOD CONTROL REPORT. ILLINOIS RIVER. 135 136 FLOOD CONTROL REPORT. ILLINOIS RIVER 137 i. FIG. NO. 17. 138 flood control report. * ILLINOIS RIVEK 139 140 FLOOD CONTROL REPORT STAGE HYDROGRAPHS FLOOD OF 192 7 PROM MORNiNG GAGE READINGS FOR REPORT ON ILLINOIS RIVER 141 142 FLOOD CONTROL REPORT ILLINOIS RIVER 143 NO. 23. 144 FLOOD CONTROL REPORT tooVs\ yjov? waver r - vatu® S7&AV.24 ILLINOIS RIVER 145 10 F C FIGURE NO. 25. 146 FLOOD CONTROL REPORT FIGURE NO. 26. ILLINOIS RIVER 147 LZ ON 01J 148 FLOOD CONTROL REPORT ILLINOIS RIVER 149 150 FLOOD CONTROL REPORT ILLINOIS RIVER 151 NO. 31 152 FLOOD CONTROL REPORT ILLINOIS RIVER 153 154 FLOOD CONTROL REPORT .00000 .0000 *S- SLOPE IN FEET PER FOOT ILLINOIS KIVER 155 '2X7+ € /Ccf /i// 6 /**M //*acC Xcvi+A £/><9«S 7*00 0 A/eoc/* /i/2 1T&73 77+acf &8K3eJ /b«r 50a 75 - 30 OOOcy.3. +80 9, 7+0 0.5/ +3025 +2975 /./+ +3067 * 29*3 +82 /2.000 O 33 +32/7 +3/83 0.73 +3238 +37+2 *43+ /+5/0 0.23 +3+./2 *3388 0.32 +3+26 *3374 +3 7 IS. 926 o./+ +37.07 *3793 0.30 +37/3 +36*85 50*? j. no -80 <3 » 80 ooo c y. 5. <5 - 700, OOOc +30 9.7*0 2. 02 +3/0/ *2897 8./5 *3A*7 *28*3 +82 /J.OOO 733 *3267 *3.33 2. 08 *3809 *3096 +3+ 7+3/0 097 +333+ 7.+2 *347/ *3329 +3 7 /&9*o 0.5+ *37.27 *36-73 o.&+ 437.42 *3636 TABLE OF ELEVATIONS FOR PROFILES SHOWN IN ILLUSTRATIONS Jvi/'/e*! O/S /¥a/err- 79. 7 5 65, OOO +5/20 / 30 65,000 + 32.00 2 so 63. OOO *32 82 8 /2 + 65, OOO * 3*. *3 + /66 6 5. OOO +85. 7<9 A /5 /oo, ooo +88 50 3 30 SO, ooo *3* 28 <5 30 70. OOO *3*. 9/ 7 /2 + <5 O. OOO * 3 *■ 9* 8 /66 50, OOO *86. 37 BACKWATER ELEVATIONS FROM TYPICAL DIAGRAMS- TYPICAL DISCHARGE DIAGRAMS FOR BACKWATER PROFILE FOR REPORT ON FLOOD CONTROL Of^ THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS BY JACOB A. HARMANCONSULTING ENGINEER -1928- FIG NO. 3 5 / I I NO! jvao IJIK.A WACOM BRIDGE >/n i cTaR/CD ROCK ✓ 1'/ \H 8O0AL vrv,,^r BROWN COUNTY 'V'V* ». y RIVE Ft SK>" ri ,v/ < T* _A*"\ ,#t v '' ILLINOIS RIVER FROM BEARDSTOWN TO MONTEZUMA SUGGESTED LEVEE SETBACKS FOR REDUCING FLOOD HEIGHTS REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS - STATE OF ILLINOIS BY JACOB A.HARMAN - CONSULTING ENGINEER 1920 Scale of Milgs l’AHX,0 1 2 \ % % % < o ■y r FIG. NO. 40 PART II—FLOOD CONTROL—MISSISSIPPI AND OHIO RIVERS. SECTION I—DISCUSSION BY THE DIVISION OF WATERWAYS. DESCRIPTION. The Mississippi River borders the State of Illinois on the West for a distance of 600 miles. Its watershed in Illinois, excluding the Illinois River, contains about 20,000 square miles. Its largest tributary, except the Illinois River, is the Rock River, into which drain the Pecatonica, the Kishwaukee and the Green Rivers. The Rock River flows into the Mississippi at Rock Island about 100 miles south of the Wisconsin State line and drains with its tributaries about 5,310 square miles in Illinois and 5,510 square miles in Wisconsin. Its second largest tributary is the Kaskaskia with a drainage area of 5,830 square miles entering the Mississippi about 60 miles south of St. Louis. The Big Muddy is another large tributary with a drainage area of 2,390 square miles. Smaller tributaries of importance are the Hen¬ derson and Edwards Rivers. The Ohio River forms the southern boundary of Illinois for a distance of 133 miles, and from the Ohio northward its tributary, the Wabash, borders the State on the east a distance of nearly 200 miles. The watershed of the Ohio in Illinois contains about 11,600 square miles of which 8,770 square miles drain by way of the Wabash and its tributaries the Embarrass, the Little Wabash and the Skillet Fork Rivers. The re¬ maining 2,800 square miles are drained by the Saline and Cache Rivers, Bay Creek and other small tributaries. FLOOD CONTROL ALONG THE MISSISSIPPI RIVER. Flood control along the tributaries of the Mississippi previously mentioned, has consisted largely of channel straightening of the main stream with the necessary ditches to carry tributary drainage. In a few cases only have levees been constructed. On the other hand, many levee districts have been formed in the bottom lands immediately adjacent to the Mississippi. Here the bottom lands extend back in some places several miles from the main stream and the building of levees early appeared an economical means of preventing overflow. Levee building on the Mississippi started first at Cairo, where pro¬ tection of city property appeared more urgent than did the protection of agricultural land, which then could be obtained at cheap prices. By 1880 farm land had risen in value so that the larger tracts of bottom 161 —11 P C 162 FLOOD CONTROL REPORT. land favorably situated could be economically protected by means of levees. Between 1880 and 1900, ten or more levee districts were formed and levees built protecting some 250,000 acres. After 1900 steady progress was made in levee building, land rose in value and the smaller tracts of land were reclaimed until today there exist more than 50 levee districts and over 500,000 acres, out of a total of 600,000 acres of Mississippi River bottom land, protected by levees. The reclamation of overflowed land and the building of levees made good progress until about 1920, when land values reached their high point due to war inflation. The drop in land values which occurred a short time later caused a cessation in formation of new districts and land reclamation since that date has consisted largely of necessary improve¬ ments to existing structures. Few districts along the Mississippi River have complete drainage. Usually a gravity outlet only at the lower end of the district is provided for the removal of water which collects behind levees. This means that during flood periods drainage is more or less obstructed or water from the river backs up the outlet, overflowing some of the low lands. In only a few cases have pumping plants been installed to completely drain the land. Many levees have been built along the Mississippi River in co¬ operation with the Federal Government. The accompanying map, Figure No. 43, shows those levees built with Federal aid and those built by the districts alone. This map shows all levee districts on both sides of the Mississippi River between Cairo and Rock Island. FLOOD CONTROL ALONG THE OHIO RIVER. The land along the north bank of the Ohio River is comparatively high and there are few areas subject to overflow. The only exceptions to this are at three points, namely, one near Cairo where bottom lands are protected by levees from overflow of both the Ohio and Mississippi Rivers, one in a bend of the river in the southeast part of Massac County and the third near Shawneetown just south of the mouth of the Wabash River. Neither of the latter two areas has been leveed. Shawneetown, however, is protected by a levee built by the State of Illinois, 1913 to 1915, at a cost of $49,000.00. FLOODS OF THE MISSISSIPPI AND OHIO RIVERS. Floods of the Mississippi River have occurred in various years but no particular flood has been a maximum for the full length of the stream. Maximum floods for different reaches of the Mississippi have occurred in different years. The flood of April, 1927, is the highest known flood for the 50 mile stretch between Cairo and Cape Girardeau. North from Cape Girardeau, a distance of 170 miles to Grafton, the flood of 1844 is a maximum. North from Grafton as far as Keithsburg, a distance of 220 miles, the flood of 1851 has never been exceeded. For the 55 mile stretch between Keithsburg and Rock Island the high water of 1892 is a maximum and northward to the Wisconsin State line the high water of 1880 is a maximum. The reason for these floods having been a maximum for a short stretch of the river only is, of course, the MISSISSIPPI AND OHIO RIVERS. 103 fact that excessive rainfall causing maximum floods, occurs over a portion of the watershed only. Figure No. 44, attached to this report, is a profile showing flood crest elevations for various Mississippi Eiver floods. This drawing shows also the location and elevations of the zeros of all river gauges. THE FLOOD OF 1927. The flood of 1927 crested at Cairo April 20th at a gauge height of 56.4, which was 2.8 feet higher than the crest of 1922 and the greatest flood of record as far north as the vicinity of Cape Girardeau. From Cape Girardeau north, as far as St. Louis, it was the highest flood since 1903. Levees were broken as far north as Chester and several drainage and levee districts containing about 100,000 acres were flooded, destroy- PICTURE NO. 7. ' - : v •- " V:- '’ - South Quincy Drainage and Levee District near Quincy, Ill. Break in Levee April 24th, 1929. ing crops and damaging property. Under the emergency flood relief act of 1927, the State of Illinois expended the sum of $557,983.00 in re¬ storing the levees of these districts. THE FLOOD OF 1929. A flood of considerable magnitude occurred in March and April, 1929, over the Mississippi as far north as Keokuk. For the stretch of the river between St. Louis and Keokuk this flood was the highest since 1903, and at one point, Quincy, Illinois, it reached a stage higher than that of 1903, and within one foot of the record flood of 1851. The levees of two districts near Quincy were broken and about 25,000 acres of bottom land flooded. 164 FLOOD CONTROL REPORT. PROTECTION' FROM FUTURE FLOODS OF THE MISSISSIPPI AND OHIO RIVERS. The flood control of the Mississippi Eiver above the month of the Ohio is a problem demanding much study. As is the case with the Illinois Eiver, levees have been built encroaching upon the flood plane, thereby raising flood heights. A levee three feet above the greatest flood of record, which occurred before levees were built, should not be relied upon to furnish complete protection. There exists also the possibility that the maximum flood of record may be exceeded. A complete study of all the storm data now available should be made to determine the probability of the occurrence of several storms over the watershed in such a way as to cause the simultaneous cresting of several important tributaries. PICTURE NO. 8. South Quincy Drainage and Levee District. View of Break about 24 hours after preceding picture was taken. Stream gauging records for the upper Mississippi should be made available by publication for several points so that proper rating curves may he made for use in flood control studies. Floods in the Ohio Eiver occur more frequently than in the Mississippi, but for the lower stretch of the river near Cairo and Mound City, flood heights from the Ohio alone are not excessive, the maximum stages being caused by the back-water effect of maximum floods of the Mississippi. A study should be made of Ohio Eiver floods as effecting existing levee heights and the outflow of important tributaries. The flood control of both the Mississippi and Ohio Eivers demands co-operation with the Federal Government and perhaps also with the several State Governments. The State of Indiana is especially con- MISSISSIPPI AND OHIO RIVERS. 165 cerned in flood control of the Wabash River and any plan for flood con¬ trol of this river should be a joint plan. FLOOD PROTECTION OF THE CITY OF CAIRO AND VICINITY. The flood protection for the City of Cairo, Mound City, Mounds and neighboring territory is believed to be the most important problem demanding attention at the present time. These cities are situated be¬ tween the Mississippi and the Ohio and are affected by floods in both rivers. They are centers of population and industry where protection to life and property is needed more than at many other localities. HISTORY OF THE CITY OF CAIRO. Situated at the junction of the Mississippi and Ohio Rivers, the earliest French explorers found the site of the present City of Cairo an ideal camping and trading post. Similarly the actual founding of Cairo PICTURE NO. 9. Degognia Drainage and Levee District on Mississippi River about 50 miles north of Cairo—High Water of 1927. Sandbagging Levee During a Storm. in 1818 as a privately owned enterprise was the result of careful con¬ sideration of the advantages of its geographical location. The slow growth of Cairo in the period of thirty-six years from 1818 to 1854 was due to financial reverses and lack of interest of its citizens in a private enterprise in which they had no voice or authority. In 1857 Cairo was incorporated by an Act of the Illinois legislature as a city with a right to be governed by its own people, and from then on its growth-was steady, until today we find a modern city of about 15,000 population. BARGE LINE TERMINAL. At the head of year around navigation on the Mississippi River Cairo has become an important barge line terminal and point for the 166 FLOOD CONTROL REPORT. transfer of freight from railroad to barge and from barge to railroad. The barge line terminal represents an inveestment of about $500,000 and is one of the largest floating docks in the country. Two principal barge lines use this dock, the Mississippi-Warrior service, operated by the Federal Government through its Inland Waterways Corporation, and the American Barge line, which is privately owned. Private lines also use it for their own freight. The volume of barge line business is increasing from year to year. The number of tons of freight handled through the Cairo Terminal during 1927 and 1928 is shown below: SOUTHBOUND. 1927. 1928. Grain . 18,347 tons 91,113 tons Merchandise. 103,867 tons 124,938 tons Total . 122,214 tons 216,051 tons NORTHBOUND. 1927 1928. Bauxite Ore . 112,550 tons 162,829 tons Merchandise . 197,389 tons 167,611 tons Total . 309,939 tons 330,440 tons Grand Total . 432,153 tons RAILROAD AND INDUSTRIAL CENTER. 546,491 tons Cairo was early recognized as the logical commercial center for this territory. In 1855 the Illinois Central Eailroad was completed into the city and since then three other railroads have been built. Cairo’s im- portance as a railroad and shipping center has made it an ideal location for various industries, especially those dealing in lumber and grain. The annual lumber business amounts in volume to 150 million feet valued at some $15,000,000. There are several grain elevators in the city and a large volume of grain business is handled. In addition to the lumber and grain business, Cairo is the center of the wholesale business in other commodities for the territory within a radius of 200 miles. HISTORY OF LEVEE BUILDING. When Cairo was first settled little was known concerning past floods. The settlers saw only a strip of low flat ground of a sandy nature, an ideal location to them commercially because of the boat traffic which passed up and down the two rivers. The building up of the present modern system of levees has been a gradual process. The following paragraphs concerning the early history of levee construction at Cairo are taken from a “Report on Flood and Drainage Problems in City of Cairo, Illinois, and Cairo Drainage Dis¬ trict” by C. E. Smith and Company, Consulting Engineers, St. Louis, Mo., published by the City of Cairo in 1922: “The first levee in Cairo was built in 1828 and surrounded a hotel near the site of the present Halliday House. By 1843 a levee encircling some 800 acres of land had been completed by the land trust. Being of light con¬ struction and low height, it had little effect towards preventing overflows in the flood of 1844. Later when additional funds became available, repairs, ad¬ ditions and extensions were made but continuing damage was experienced in succeeding floods. In the 1849 flood the west levee, along the Mississippi, was MISSISSIPPI AND OHIO RIVERS. 167 cut for a distance of 1,625 feet. During the June flood of 1858 it again gave way and caused the last flood that ever submerged Cairo. “In 1862, through neglect, erosion set in on the Ohio levee, between Eighth and Fourteenth Streets, and necessitated expensive repairs. In 1875 radical changes in the channel of the Mississippi occurred and a section of the Mississippi levee, near 33rd Street, was undermined and abandoned. An entirely new section on what is now called New Levee Street was con¬ structed in 1876 to replace it. After 1875 we learn of little trouble with levees until the flood of 1912 wflien both the Mississippi and Ohio levees in the drainage district north of Cairo were breached and Cairo cut off for days from outside communication by rail although the city itself was not inundated and water traffic continued. One year later, in 1913, when the record flood of 54.8 feet occurred, heroic measures were required to keep the water out of the city, but as in every flood since 1858 the people won. Not once in 65 years from 1858 to 1922 has Cairo been under water.” In 1914 and 1915 through appropriations by the City of Cairo and the State and Federal Governments the levees were again enlarged. The work done by the State at this time consisted of a concrete wall, 1.61 miles in length along the Ohio River levee of the city. In the spring of 1927 a record flood occurred which reached a stage of 56.4 or within 3.6 feet of the top of the levee and the water was kept out of the city and the drainage district only by constant effort and the expenditure of a large sum of money. In 1927 and 1928 the State of Illinois, under its emergency flood relief act, repaired the damage done to the city levee and that of the Cairo Drainage District. At the present time (1929) the Federal Government is raising and enlarging the Mississippi River levee of the City of Cairo and of the Cairo Drainage District and is planning to raise and strengthen the Ohio' River levee. COST OF LEVEES. The cost to date of the levee system protecting the City of Cairo and the Cairo Drainage District is approximately as follows: Expended by various agencies previous to 1913 (estimated). $1,500,000.00 Federal Government, 1913-1914. 250,000.00 City of Cairo, railroads and drainage district by taxation, 1913-1914 400,000.00 State of Illinois, 1913-1914. 250,000.00 State of Illinois, 1915. 25,000.00 City of Cairo and drainage district repairs to levees, 1916-1928 about 50,000.00 State of Illinois, 1927-1928, levee repairs... 347,000.00 Total. $2,822,000.00 The above does not include the amount spent by the Federal Gov¬ ernment in 1928-29 in raising the Mississippi River levee nor sums spent for revetment work by the Federal Government nor the money spent by various agencies in fighting floods. NECESSITY OF ADDITIONAL PROTECTION. A great catastrophe and the loss of many lives would doubtless have resulted had the levees protecting the City of Cairo given way during the flood of 1927. That this catastrophe was narrowly averted is the belief of everyone having knowledge of the situation existing at that time. It required the expenditure of about $140,000 and all available labor re¬ sources of the city, the drainage district, the railroads and the various large industries to prepare and place along the levees the hundreds of thousands of sand bags required to check slides and “well up” the num¬ erous sand boils inside the levees which were a constant menace. 168 FLOOD CONTROL REPORT. The flood reached a height of 59.3 at the Cache River, over-topping the levee for long stretches by a foot or more and requiring the building of timber bulkheads to hold out the water. Near the crest of the flood the Dorena crevasse occurred down the river just north of New Madrid, and the flood waters finding a new outlet, were prevented from reaching the crest of 58 or 58.5 at Cairo gauge predicted by the 'Weather Bureau. A height of 58.5 at Cairo gauge using the same river slope would have meant a height of 61.4; at Cache River levee, the Mississippi and Cache River levees of the Cairo Drainage District would have been over-topped, and it is probable that the cross-levee between the district and the City of Cairo would also have given way, thus flooding the city. It is evident, therefore, that the flood of 1927 was kept out of the City of Cairo only through the failure of the levee system below that point. Such a flood occurring under present conditions, with the Dorena crevasse repaired, might prove disastrous. The repairing of the Cache River levee by the State of Illinois and the raising of the Mississippi River levee of the Cairo Drainage District by the Federal Government were previously mentioned as improvements accomplished since the flood of 1927. These improvements, and other improvements planned by the Federal Government, while of great im¬ portance are insufficient and in order to assure the future safety of Cairo additional protection must be provided. SAND BOILS AND SEEPAGE. On account of the sandy nature of the sub-soil a’t Cairo there is a great deal of seepage during high water periods and sand boils within the levees become a serious menace. A sand boil may be described as a spring, the water being under sufficient pressure and velocity to carry in suspension silt and sand from underlying strata. Such a boil when located near the inside toe of a levee may cause a settlement of the latter or it may develop an under¬ ground connection between the river and the inside area causing a ‘Flow out.” The greater danger lies in the settlement of the levee caused by the removal of large quantities of sand underneath, to such an extent that it may become weakened or over-topped by the flood. Contrary to popular belief sand boils and seep water behind levees are not usually fed directly by rivers but from ground water put under pressure through lack of an outlet during highwater periods. Under certain conditions, however, it is believed that the flow may come directly from the river. For example where a sand strata outcrops on a river bank at a sufficiently low elevation, there will he a ground water flow toward the river during low water periods. During high water or flood periods a reversal of flow may occur resulting in seepage and sand boils from this same strata. Ordinarily this reversal of flow will be prevented through the filtering action of the sand, the voids on the outside being soon filled with silt removed from the water; however, in many cases the scouring action of the river current will prevent the formation of any layer of sediment of sufficient thickness to exclude leakage into the sand strata. It is believed that seepage of this kind occurred in several in¬ stances during the 1927 flood at Cairo. One case in mind is the boil at MISSISSIPPI AND OHIO RIVERS. 1G9 the Cairo Ice-Cream and Milk Company plant described by Mr. Geo. F. Dewey, City Engineer, as follows: “At two or three prominent sand boils the discharge was welled up with sack dirt to approximately a 48 foot elevation not checking the water flow but retaining the solids. One such large boil developed at the Cairo Ice Cream and Milk Company plant at Fourth and Commercial Avenue, around the casing of a new artesian well driven in August, 1926, to a depth of 190 feet. This boil was approximately 425 feet from the Ohio River and dis¬ charged several carloads of sand therefrom, and, after the recession of the river produced a subsidence in the Ohio river bank at a point from 75 to 125 feet south of Fourth Street, the location of the Government concrete river gauge.” PICTURE NO. 10. Cairo Drainage District. Mississippi River Levee during High water of 1927. Inner Slope of Levee Sandbagged to Prevent Slides. The subsidence above mentioned was clearly in evidence in January, 1929, and extended for a width of about 200 feet from the concrete wall down to and under the water surface, the gauge height at that time being about 18. Outcropping sand was noted a few feet above the waters edge. There is no direct evidence that water from the river entered through this sand, but it seems probable that it did. The greatest amount of subsidence, amounting to four or five feet, oc¬ curred only after about 600 cubic yards of rock had been dumped along the outside toe of the concrete wall to fill to original grade. This same sand boil also caused some settlement of the foundations of several build¬ ings on the inside of the concrete wall at this locality. 170 FLOOD CONTROL REPORT. The concrete wall at this point is about 16 feet high from bottom of foundation to top, with an outside toe of the foundation resting on inter¬ locking steel sheet piling 16 feet long, driven into a sand strata of in¬ definite thickness. This wall retains on the inside a fill with railroad ballast and tracks to a height within four or five feet of the top. That there was no apparent settlement of this wall or the fill which it sup¬ ports is remarkable. Will the movement of large bodies of sand and water under the more solid soil and permanent structures, such as a concrete wall and buildings resting thereon, although stopped for the time being, create an unstable condition which may lead to a recurrence of the movement dur¬ ing future flood periods and eventually lead to disaster ? Questions such PICTURE NO. 11. Cairo Drainage District. Ohio River Levee during High Water of 1927. Sand Boil Area “Welled Up” with Sand Bags. as the above complicate the situation at Cairo and make the prevention of sand boils of vital importance. The usual method of checking a sand boil is by means of a ring of sacks filled with sand or earth impounding the flowing water as in a well so as to create a counterhead which stops the inflow of the water. In some cases sub-levees are built to pond the water over wide areas behind the main levees. Both of these methods are expensive and of a temporary character and little adapted to a thickly populated locality. Standing water greatly detracts from the appearance of the city and creates unfavorable comment concerning the safety of the levees. MISSISSIPPI AND OHIO RIVERS. 171 There is only one permanent satisfactory method and that is to fill in all low areas to an elevation high enough to prevent the recurrence of sand boils. The sewer system of the City of Cairo, which is relied upon to re¬ move seepage, drains by gravity at all river stages below 33 feet on the Cairo gauge. Above this stage pumps are operated as required, the maximum operating capacity at the higher stages being represented by one 18 inch and four 20 inch centrifugal pumps. Mr. George Dewey, City Engineer, furnished the following figures concerning pumping operations during the period of March 16th to May 5th, 1927: Rainfall (18.35") . 653,762,066 gallons 17 per cent Artesian and driven wells. 84,000,000 gallons 2 per cent City Water Works . 250,000,000 gallons 7 per cent Traction Co. 250,000,000 gallons 7 per cent Total visible supply.1,237,862,066 gallons 33 percent Total water pumped.3,768,480,000 gallons 100 per cent Seepage .2,530,617,934 gallons 67 percent PICTURE NO. 12. Cairo, Ill., High Water of 1927, a Typical Sand Boil. The cost of pumping during the past 12 years has amounted to $109,000, or an average of about $9,000 per year. SLIDES. The occurance of slides is not the least of the dangers to be fought at Cairo in maintaining the levees against high water. As a usual thing a slide on the inside slope of a levee is caused by the line of saturation which varies from a gradient of 5 to 1 to one of 7 or 8 to 1 extending outside of the inside slope. In such case the inside 172 FLOOD CONTROL REPORT. toe of the levee has a tendency to slough off. This is prevented by the placing of sand bags, or other obstructions in the way. Slides sometimes occur on the outside slopes of the Cairo levees due to the escape of ground water into the river on receding stages or by the movement of a layer of quicksand. At Cairo the situation is aggravated by seep water being allowed to stand against the inside toe of the levee and by the fact that large quantities of cinder ballast or other porous material have been used from time to time in raising the railroad tracks on top of the levees. Porous material in the levee embankment itself has been the cause of many of the levee slides at Cairo. The remedy for this situation is the building of banquetts on the inside slopes of levees or the use of flat inside slopes so as to bring the line, of saturation inside the levee section. This construction will also tend to prevent sand boils. Slides on the outside slope can be per¬ manently prevented only by constructing levees of proper material, with flatter outside slopes and located far enough away from the river bank. In 1915 serious slides developed at three points on the outside of the Ohio River levee at Cairo just south of the Illinois Central Railroad bridge. The State Legislature appropriated funds to make the necessary repairs and the work was done by contract during the year 1916. The repairs consisted of wooden sheet piling driven near the bottom of the slope supported by round piling and stone filled cribbing, and a line of steel sheet piling near the crown of the levee anchored by means of tie- rods to heavy concrete blocks on the inside. Since these repairs were made some settlement has occurred and there has been some lateral top of the steel sheet piling. Some of this movement occurred after the movement of the sub-soil, and the filling resting thereon, forcing out the 1927 flood. During the summer of 1928 the Federal Government placed concrete revetment at this point, and it is believed that conditions are now stable and that there will be no more trouble. However, this is a danger point which should receive special attention in planning Cairo’s flood protection. CAVIXG BANKS. Much trouble in times past has been caused by caving banks on both the Mississippi and the Ohio sides of Cairo and the Cairo Drainage Dis¬ trict. A large amount of revetment, placed by the Federal Government has successfully prevented encroachment, but much more work needs to be done, especially along the Ohio River. It is believed that the 17. S. Government engineers have the situation well in hand and that they will continue to give attention to it as future occasion demands. Neverthe¬ less, there should be no interruption in the prosecution of a program which will provide adequate protection. THE CAIRO DRAINAGE DISTRICT. The interests of the Cairo Drainage District are so interwoven with those of the City of Cairo that they must be considered as one in mat¬ ters of flood protection. Future City, a suburb of Cairo, lies in the drainage district, and all future expansion of Cairo must be northward in that direction. The principal industries, upon which the inhabitants of MISSISSIPPI AND OHIO RIVERS. 173 Cairo rely for employment, and upon which the future prosperity of Cairo depends, are located in the drainage district. These industries in¬ clude several large lumber companies doing an annual business of over $10,000,000.00. There are available many excellent factory sites, con¬ venient to both rail and water transportation, which point to the early industrial development of the whole district. Flooding of the Cairo Drainage District would seriously interfere with railroad and highway communication into Cairo from the north. It is recommended, therefore, that the drainage district be included with Cairo in any plans for ad¬ ditional flood protection. MOUNDS AND MOUND CITY. Mound City has a population of about 3,200 and is located on the Ohio River about five miles north of Cairo. It is an industrial city hav- ing several large wood working plants, a large canning factory and a shipyard. Protection against floods is furnished Mound City by a “ring” levee completely surrounding the town. This levee was first built in 1860, enlarged in 1885 and in 1899, and again in 1914. In the latter year and in 1915 the State of Illinois appropriated $60,000 toward the work which included a concrete wall along the water front. The total cost of this levee has amounted to over $150,000. The flood of April, 1927, was kept out of Mound City only by sand-bagging and building of timber bulkheads. Considerable damage was done to the levee at this time and repairs were made by the State in 1928 under the terms of the flood relief act. The City of Mounds, about two miles west of Mound City, is the first station on the Illinois Central Railroad out of Cairo. This town was flooded in 1927 by the Mississippi River finding its way across the Cache River basin into the Ohio River. The protection of both Mound City and Mounds should be a part of any comprehensive flood control plan dealing with Cairo. THE ARMY FLOOD CONTROL PLAN AS AFFECTING CAIRO. The Mississippi River flood control act, appropriating $325,000,000 for flood control construction along the Mississippi River, was passed during the first session of the 70th Congress (approved May 15, 1928). This act (printed in full at the end of this report) provides for the adoption of the flood control plan of the Chief of Engineers of the Army, subject to modification by the President as to any controversial features subsequent to recommendations by the Mississippi Flood Control Board. The Flood Control Board, in its report to the President, dated August 8th, 1928, recommends the plan of the Chief of Engineers practically unchanged, and it is assumed that the intention is to carry out this plan without substantial modification. The provisions of the plan which are intended to relieve the flood situation at Cairo are: (a) The levees protecting Cairo and the territory immediately north of Cairo as far as the Cache River are to be strengthened and raised to a height equivalent to 60 feet on the Cairo gauge (substantially their present height). 174 FLOOD CONTROL REPORT. (b) A set-back floodway of five miles average width is provided from Bird’s Point to New Madrid, on the other side of the Mississippi from Cairo, capable of carrying about 450,000 second-feet if entirely cleared, the existing river side levee to have fuse-plug sections at each end, the one on the north to be built to elevation 55 on the Cairo gauge. This is the most vital part of the Federal Governments’ flood control program, so far as it relates to the City of Cairo, and since Cairo, more than any other city in the State of Illinois, is affected by flood conditions of the Mississippi River, the people of the State of Illinois are par¬ ticularly interested in seeing that the plans proposed are adequate and acceptable for Cairo’s protection. FLOOD CONTROL BOARD'S VIEW. In explanation of the design of the Birds Point to New Madrid Floodway and of its effect on flood levels at Cairo as computed by the Chief of Engineers, paragraphs 20 and 21 of the Report of the Flood Control Board to the President are quoted herewith: “20. From Birds Point to New Madrid, Mo., the floodway provided for by the adopted project will hold the maximum flood predicted as possible to 59 on the Cairo gauge and one foot below the proposed levee height. This will give a reasonable degree of safety to Cairo with its 15,000 inhabitants. In addition, this floodway, by reducing flood heights, will render the St. Francis Basin in southeast Missouri and Arkansas less liable to an accidental crevasse due to excessive flood heights. The riverside floodway plan offers the best solution for the situation at Cairo and vicinity because it gives a greater lowering of the flood plane than any other practical plan and pro¬ vides greater safety to more property and lives. It is the one desired by the greatest number of those vitally interested. The Mississippi River Commis¬ sion plan raises the levees opposite Cairo two feet, the same as the adopted plan, but makes no provision against a superflood. “21. A public hearing was held at New Madrid, Mo., at which the pro¬ posed Birds Point-New Madrid superstage floodway was freely discussed. In addition, an extensive treatise on the subject was submitted to the board by interested parties. Some divergent conclusions on the hydraulics involved have been expressed. However, when these are analyzed closely it is found that the practical result of the floodway will be what is desired. The first experts to study stages at Cairo, Ill., predicted the maximum possible flood as one which, if confined, would produce a stage of 66; and this figure cor¬ responded to a discharge of from 2,250,000 to 2,400,000 second-feet. The maximum stage was deduced on the assumption that each foot of gauge height above stages which have occurred would be produced by a certain amount of water computed from past measurements. Later other experts calculated that as the river rose and the slope became steeper, each foot on the gauge would represent a greater amount of water. This resulted in a stage, if confined, of about 63 for the same total discharge that was used in the first place as corresponding to 66 on the gauge. In both cases, if about 450,000 second-feet should be allowed to pass out of the river channel the resulting gauge height at Cairo would be about 59. All experts have found that the stretch of minimum capacity of the flood way would carry this amount or more. One expert expressed it by saying that the critical stretch, uncleared, would carry 150,000 second-feet and if cleared it would take about four times this amount (600,000 second-feet). The stretch in question is cleared and will undoubtedly remain cleared, so there need be no appre¬ hension about its accommodating 450,000 second-feet, which amount taken out of the river in a superflood will hold the Cairo gauge to about 59. The plan of the adopted project proposes to permit water to spill into the flood¬ way at stage 55 Cairo, so that great floods of lesser volume than the maxi¬ mum flood will also be reduced in height. The 1927 flood actually produced a stage of 56.4 at Cairo without accident and an equal flood under the plan of the adopted project will produce a stage of about 55^ for a short time MISSISSIPPI AND OHIO RIVERS. 175 only. It should be remembered that a flood approximating in volume the maximum predicted as possible can, according to predictions, occur, on the average, only once in 200 years.” PROTECTION OF CAIRO A, VITAL MATTER. Whether the Army plan, now being put in operation by the Federal Government, will or will not adequately protect the City of Cairo from danger of destruction by any possible flood, is a question of vital im¬ portance to the people and government of the State of Illinois. Engineers do not all agree that the plans proposed are adequate or safe. The Division of Waterways has considered this subject as being far too serious to be ignored or dismissed without full consideration. In harmony with this view, and to the end that opposing views might be presented, an arrangement was made with the Berthe Engineering Com¬ pany to make an independent investigation and report on the entire flood situation in the vicinity of Cairo, with recommendations as to what other or further flood protective works, if any, are necessary, perman¬ ently and positively, to protect Cairo, Mounds and Mound City from inundation. Essential parts of said report are included herein. SECTION II—REPORT OF THE BERTHE ENGINEERING CO. THE PROBLEM AT CAIRO. The real problem of river control begins at Cairo and the com¬ plexity of this problem is such that it not only requires thorough in¬ vestigation and careful study in order that a safe and sound solution be finally adopted, but, due to the influence which the manner of solution will inevitably exert upon the commercial and economic future of the City of Cairo, and through that, upon the entire southern section of Illinois included within the trade territory of that city, such conditions may justify some participation by the State itself in certain items of cost if by such participation a plan of greater economic benefit to that section of Illinois will result. FLOOD MENACE AT CAIRO. The importance and seriousness of the flood menace at Cairo is ad¬ mitted. As an indication of the seriousness of that flood menace we quote the following from the report of the Chief of Engineers: “Cairo, Illinois, has a population of about 15,000. Its levee is at elevation 60 on the gauge. Parts of the city are 20 feet below this ele¬ vation. This city is situated on the point of land between the Mississippi and Ohi’o where escape from a flood which overflows the levees will be almost impossible. The 15,000 people should be protected against the highest water predicted as possible. The actual top of the present levee is 60. It has been estimated that with the discharge confined within the limits of the present levee, stages are possible as high as six feet above the present levee top.” MEASURE OF PROTECTION NECESSARY. As indicating the measure of protection which should be provided under such conditions, and that it should not be measured by the yard- 176 FLOOD CONTROL REPORT. stick of cost but by the standard of safety; and as also demonstrating that there is a sure remedy, although not included or recommended in his plan, we quote this further extract from the report of the Chief of Engineers: “The catastrophe resulting from a crevasse on a city front would be so appalling that no measure should he spared to prevent it. A sure remedy would be the filling in of the land to bring it above the limit of dangerous overflow.” DEMAND FOR FURTHER STUDY. As an indication of the complexity of this problem we quote from an editorial in the February 23, 1928, issue of the Engineering News- Record as follows: “Probably nowhere else up and down the Mississippi River does the engineer face a harder flood control problem than at Cairo, Illinois. . By its very nature the Cairo problem involves all of the complex financial, physical and political aspects of Mississippi River Flood Control as a whole.” LOCATION AND ECONOMIC IMPORTANCE. Cairo is located at the extreme southern tip of the State of Illinois on a narrow strip of alluvial land built up by the river flood plane be¬ tween the Mississippi and Ohio Rivers at their junction. It is at the head of year around navigation on the Mississippi River, an important barge line terminal and a “breaking” point for freight rates in every direction, making it a natural and logical location for various manufac¬ turing, assembling and distributing industries. It has a present popula¬ tion of approximately 15,000 of which about two-thirds are white. The city is served by the Illinois Central, Missouri Pacific, Mobile & Ohio and Big Four railroads as well as by river connections with the Federal barge line and other river carriers. A highway bridge now under construction will form a connecting link between the State highway systems of Illinois and Missouri at this location. CITY OF CAIRO VALUATIONS. The assessed valuation of the City of Cairo proper for taxation pur¬ poses is $11,376,209.00, exclusive of railroad and utility property. The total assessment for Alexander County, including the City of Cairo and industrial district is $19,612,616. The actual values have been estimated at from $36,000,000 to $50,000,000. PROTECTIVE WORKS AND TOPOGRAPHY. The city is surrounded by a levee system about seven miles in length and contains an area of 1,300 acres within the levee system. The ground elevations in the city vary from 310 to 323 feet above zero of the Memphis datum plane or from 33 to 46 feet above the zero of the Cairo gauge. The zero of the Cairo gauge being equivalent to 277.04 Memphis datum. Memphis datum will be used in this report as being more con¬ venient since all levee grades in Missouri, Tennessee and Kentucky are referred to that datum. The average ground elevations in Cairo are about 320 Memphis datum or 43 feet on the Cairo gauge. MISSISSIPPI AND OHIO RIVERS. 177 The elevation of the lands on the Missouri bank opposite Cairo vary from 322 to 326 feet, being from twelve to sixteen feet higher than the lowest land in Cairo and from two to six feet higher than the average elevation of Cairo. The grade or top of the Cairo levees is equivalent to 60 feet on the Cairo gauge, the top of the concrete wall at the gauge being at elevation 337 Memphis datum. The section of the ]evee line along the Ohio River front of the city consists of a concrete wall backed up with earth fill, the top of the wall extending from two to eight feet above the top of the earth fill and the foot of the wall being protected against under-seepage with a line of interlocking steel sheet piling. The remainder of the levee line is of earth, the major portion serving a joint use as a railway em¬ bankment. All of the controlling city levees are up to the equivalent of 60 feet on the Cairo gauge and although there is considerable variation in section, all have wide crowns and no sections have been noted with less than three to one side slopes. While the use as an embankment for railway trackage appears to possess a material advantage in a more thorough solidification, as well as facilitating maintenance and emerg¬ ency work, there is an attendant disadvantage in that the penetration of ballast carrying with it a certain percentage of voids into the center of the embankment causes this to act as a reservoir for rain water which tends to bring about slides in the embankment in finding its way out. This has probably been the incipient cause of the slides which have de¬ veloped at certain locations along the earthen levees. HEIGHT OF CAIRO LEVEES AND COMPARATIVE DIFFERENTIALS. The heights of the city levees vary from 15 to 24 feet and compared with other levees in the alluvial valley are not only not excessive but somewhat below the average. The height of the levees protecting the City of New Orleans vary from 8 to 20 feet and some points in the city are 26y 2 feet below the levee grade. Levee heights of from 35 to 40 feet are not unusual in the lower valley. Improved street levels in Cairo are generally from 15 to 17 feet below the present levee grades but some of the lower unimproved areas in the city are as much as 27 feet below the levee grade although such areas are limited. SAND BOILS. While the underlying sub-strata of the city is of sand and gravel, there is a superimposed top strata of silt and clay which varies in thick¬ ness from only a foot or two in places to depths as great as ten or twelve feet. By reason of the porous sub-strata beneath the top soil, above-bank river stages bring about a rise in ground water pressure against the top soil. This accounts for the prevalence of sand boils during extreme high water stages at points where the top soil is thin or where it has been penetrated by wells, foundations or other excavations. It is conceded that sand boils constitute a serious menace to the maintenance of levees and bring about an increased hazard in times of high water. They should be eliminated in all instances and especially so in city areas. —12 F C 178 FLOOD CONTROL REPORT. While sub-levees and water blankets may be and are used to nullify their effects in agricultural areas, such methods are not adaptable to city con¬ ditions and they should be eliminated by a reduction in the differential between flood plane and ground levels. C. E. SMITH REPORT. A report by C. E. Smith, Consulting Engineer, retained by the City of Cairo in 1922 for a study and report on its flood problems, shows ex¬ tensive investigations into sub-soil conditions at Cairo, locations where sand boils have been prevalent and advisable remedies. The report con¬ tains much other valuable information, and extracts from it will be found in the text. DRAINAGE AND INDUSTRIAL DISTRICT. Just north of the City of Cairo is the Cairo Drainage District com¬ prising some 6,000 acres of land. Most of this is farming land although possibly about 600 or 700 acres is used as an industrial district at what is known as Future City and the Goose Pond Area along the Ohio Eiver front. This district is bounded by the Mississippi Eiver on the west. Cache Eiver on the north, the Ohio Eiver on the east and the City of Cairo on the south. The population of the drainage district was esti¬ mated in 1922 as about 2,500 but is now considerably less, probably not in excess of 2,000. The district is entirely surrounded by levees, the length of the surrounding levee line being between 14 and 15 miles and, except for the south levee which is part of the City of Cairo levee system, this levee line previous to 1927 flood was constructed to a grade equival¬ ent to from 57 to 58 feet on the Cairo gauge. Except for the levee along the south bank of Cache Eiver these levees also serve as railroad em¬ bankments. The protection of the area with this district presents no great difficulties. Being encircled by the levee system mechanical drain¬ age becomes necessary during flood stages in the rivers. LENGTH AND GRADES OF CAIRO LEVEE SYSTEMS. The following tabulation of the levee system of the City of Cairo and the Cairo Drainage District appears in the C. E. Smith report herein before referred to and as there have been no changes other than main¬ tenance since the date of that report, remains correct today. The length and crown elevations of levees surrounding Cairo and the Drainage District, exclusive of cross levee, are as follows: CITY OF CAIRO. Location. Length. Crown elevation— Cairo gage. Feet. Miles. Ohio side— Concrete__ 8,520 4,550 18,800 1.61 .86 3.56 60.0' 60.0' 60.0' Earth_ Mississippi side— Earth_ Total_____ 31,870 6.03 MISSISSIPPI AND OHIO RIVERS. 179 CAIRO DRAINAGE DISTRICT. Location. Length. Crown elevation— Feet. Miles. Cairo gage. Ohio levee— Earth_ 14,916 2.82 58.0' Mississippi levee— Earth_ 33,270 28,253 6.30 57.0 to 58.0' Cache levee— Earth___ 5.33 Total.._ 76,439 14.45 With the exception of the Cache River levee, at north end of Drain¬ age District, all other levees are almost wholly occupied with railroad tracks. This occupancy occasions crown widths in excess of usual levee practice but the customary standard slopes of 3 to 1 appears to be well maintained over the entire system. The Cache River levee has been strengthened by the State of Illinois with a 30-foot banquette added to the landside section. RIVER STAGES AND FLOOD VOLUMES AT CAIRO— 1882 TO 1927 INCLUSIVE. In 1927 the river rose to a stage of 56.4 on the Cairo gauge, being the highest stage ever recorded at Cairo and it was estimated by the Weather Bureau that except for the relief resulting from the Dorena crevasse, 35 miles below Cairo, the river would have reached a stage of 57.7 or 58 feet. The local forecaster estimated 58 to 58 The following is a table of river stages and discharges at Cairo, Illinois as measured and shown by publications of the Mississippi River Commission. Year. Cairo crest gage readings. Discharge, second feet. Discharge measured at— 1882________ 51.87 *1,562,000 (•*) 1,520,000 (**) *1,686,000 1,543,000 2,015,000 2,015,000 1,775,000 1,527,000 1,501,000 111,800,000 Helena, f 1883..____ 52.17 1884_______ 51.79 Fulton.J 1886__ 51.02 1903_____ 50.57 Helena. 1907............ 50.33 Columbus.1 Columbus.^ Columbus.1 Columbus.^ Columbus.1 Columbus^ Hickman. 1912......... 53.94 1913...... 54.69 1916....... 53.21 1920........... 51.40 1922........ 53.60 1927...... 56.40 * Discharge read at Helena includes contributions from the St. John, Obion and St. Francis water¬ sheds and are therefore in excess of actual discharge at Cairo. + Gage, 46.5. ** No discharge measurements. X Gage, 35. * Actual measurement at Columbus was 1,728,000 second feet, but was made when gage was 53.7 or 2.7' below crest. Discharge computed by Mississippi River Commission to have been 1,800,000 second feet. In 1916 and 1922 there was no crevasse which affected the Cairo gauge. In 1912 and 1913 there were crevasses both above and below Cairo, and in 1927 the Dorena crevasse, 30 miles below Cairo, took from 180 FLOOD CONTROL REPORT. iy 2 to 2 feet off the crest. The effect of such crevasse was augmented by the diversion which obtained at and above New Madrid into the St. Francis basin and return water from which did not re-enter the main river until it reached the mouth of the St. Francis River near Helena. SIZE OF FLOOD TO PROTECT AGAINST. How large or great a flood should we protect against? It is gen¬ erally conceded that 100 per cent protection is economically unfeasible. How far should we go and where should we stop? As a starting point, what has occurred can occur again and thus certainly protection should be provided against the greatest flood of record. From the character of development which has taken place in the alluvial valley during the past two decades, even with the partial protection afforded, we can form some concept of that which will follow the provision of greater protection. Fortunately in the 1927 flood, compared with the area flooded, the known loss of life was small. This was due to the fact that there were no crevasses upon city fronts. Yet over 600,000 people were driven from their homes. In another 20 years a similar flood affecting the same areas would probably make homeless a number twice as large. We have been following a policy of designing flood control works to protect against the greatest flood of record. But records were broken in 1912 and 1913, along certain reaches in 1922 and finally again in 1927, four records over a span of 16 years, an average of a record every four years. Presumably following that policy we would eventually reach the greatest flood and protection against all floods of the future, but when a single flood can cause a known loss of over 200 lives, direct property damages of a quarter of a billion dollars and drive 600,000 people from their homes the hazard has become too great and the fallacy of the continuation of such a policy has become apparent. The time has come to give some attention to probabilities. MAXIMUM PROBABLE FLOOD AS DETERMINED BY MISSISSIPPI RIVER COMMISSION. The Mississippi River Commission working upon the basis of coin¬ cidental rainfall and flood volumes has arrived at the conclusion that the maximum probable flood along the lower Mississippi is represented by a flood volume of 25 per cent greater than that of 1927 at Cairo and 10 per cent greater below the mouth of the Arkansas. MAXIMUM POSSIBLE FLOOD AS DETERMINED BY WEATHER BUREAU. Working from another basis, that of relative stages as is used by the weather bureau in computing flood stages for daily forecast, the weather bureau arrived at a stage of 65 feet at Cairo as the maximum stage possible which Doctor Frankenfeld, Senior Meteorologist of the Bureau, stated probably would not happen once in 10,000 years but that it was’ within the realm of possibility. The publications of the bureau give this maximum possible stage at Cairo as from 65.5 to 66 feet. It also gives the 1927 confined stage at Cairo at from 57.7 to 58 feet. With a flood equal to that of 1913 in the Upper Ohio coincident with the 1927 MISSISSIPPI AND OHIO RIVERS. 181 flood in the Upper Mississippi the confined stage at Cairo is estimated at from 62 to 62^ feet. The probability of such a flood is not stated, but in consideration of the fact that there is no record of any such flood ever having occurred, and the further estimate of the Weather Bureau that 200 years would probably elapse before the recurrence of another flood along the reach below Vicksburg as great as that of 1927, it would seem reasonable to consider that such a flood as would result at Cairo from a coincidence of the 1927 Mississippi flood and the 1913 Ohio flood would take at least as long a probable time interval, that is, of not oftener than once in 200 years. RELATIVE IMPORTANCE OF PROTECTION. It is respectfully submitted that the importance of protection to agricultural districts as compared with that of protection to congested centers of population, as in large cities where the human life hazard enters to so much larger an extent into the equation, to such an extent in fact that General Jadwin stated that “the catastrophe resulting from a crevasse on a city front would be so appalling that no measure should be spared to prevent it,” is not equivalent to the latter instance and that there appears to be no reason which would make equal protection economically justifiable. It must first be remembered that these greatest floods, which are listed as barely within the realm of possibility, may never occur, and in the judgment of our best meteorologists would occur only once in ten thousand years, if at all. It seems reasonable that in view of the human life hazard we might and should protect our congested centers of population against even this remotely possible flood, but should we attempt upon any ground to justify an expenditure at this time to protect the agricultural lands in the valley against an improbable but remotely possible flood the cycle of probable recurrence of which would be but once in ten thousand years ? EMERGENCY PROTECTION REQUIRED AT CAIRO. Immediate Flood Hazards .—While it is conceded that floods mav occur in the future which would overtop the Cairo levees it must be remembered that such a flood never has occurred. It will also be noted that with the present grade of the levees in Missouri, which are from one to two feet lower than at Cairo, it would require a greater than the probable flood to overtop the Cairo levees as the entire line of Missouri levees would first be overtopped. The one principal danger with which Cairo is confronted is the lack of stability of her sub-soil and the prevalence of sand boils with the possibility that stages which approximated, but did not overtop her levees, might bring about pressures which would cause failures or blow outs in the levee foundations. There is also the question if the present levee sections are in all cases such as would successfully withstand long sustained flood periods with the flood plane within a foot of their top without complete saturation and danger from sloughing. 182 FLOOD CONTROL REPORT. REDUCTION OF DIFFERENTIALS BY FILLING METHOD 100 PER CENT EFFECTIVE IN EVERY FLOOD. The danger from boils is more imminent than the danger of over¬ topping the present levees. A flood much less than the maximum might produce a disaster through uncontrollable seepage. Proposed methods of reducing differentials by diversion are only partially effec¬ tive or wholly ineffective against lesser floods than the maximum. The stages which caused the troubles in 1922 described in the Smith report are even below those at which diversion would start under the proposed plan. Raising the lowest portions of the city would largely eliminate this danger and reduce such hazard to a minimum and such method of reducing differentials would be fully effective in every flood. It would seem axiomatic that this should be the first step taken to secure a flood safe city. Therefore the immediate emergency work, which is work that will be required regardless of any plan that may be adopted, should consist first of the filling up of the lower city areas to the elevations indicated in the following extract from the C. E. Smith report. According to that report this will require a total of 3,150,000 cubic yards within the city itself and 1,250,750 cubic yards in the industrial part of the Drainage District listed in that report as the Goose Pond Area, being a total of 4,400,750 cubic yards. HAZARDS EMPHASIZED IN C. E. SMITH REPORT. We quote the following from the C. E. Smith report as to the seriousness of the sand boil situation at Cairo and in the industrial district. It will be noted that these observations were the result of an investigation based primarily upon conditions which obtained during the 1922 flood which only reached 53.6 on the Cairo gauge, 5.4 feet below the maximum flood level provided in the Jadwin plan assuming the flood plane reduction works included in that plan to be 100 per cent effective. In other words, the Jadwin plan would permit an in¬ crease in differentials between flood plane and city levels at Cairo of 5.4 feet over the actual differentials which obtained in 1922 and 2.6 over those which obtained at the maximum 1927 flood crest, without providing any remedy for this evil other than the strengthening of levee sections. FROM C. E. SMITH REPORT. These sand boils and seep water studies should prove enlightening to the people of Cairo and awaken them to the necessity for promptly dealing with both problems. There is not much consolation in knowing that they originate in ground water instead of in the rivers and no one should let our explanation of the phenomena minimize, in their minds, the danger that is created by their annual appearance. More levees, perhaps, have failed in the Mississippi Valley through undermining by sand boils and a softening of the base by seep water than from any other cause. Seep water rises slowly but sand boils break out suddenly and no one, charged with the maintenance of the MISSISSIPPI AND OHIO RIVERS. 183 levees during high water, knowns when or where or what the result of the next one will be. They are treacherous and when combined with seep water there is presented one of the greatest evils to safety in flood protection. About the only successful way to prevent sand boils and seep water is to increase the surface over the affected areas so that greater re¬ sistance will be offered to the rise of ground water, and increase the amount of pumping so as to lower the ground water level. That means that the low areas in the city must be filled and raised to a height to which ground water will not carry with a reasonable amount of pumping. The following itemized statement taken from the C. E. Smith re¬ port includes those items which should be considered as necessary under any plan and which comprise the 4,400,750 cubic yards of filling recom¬ mended in a foregoing paragraph. The work while emergent, forms a necessary, in fact, the most necessary part of the permanent protective works for Cairo. Its ommission from flood control plan leaves the City of Cairo without any assured and certain protection from ultimate cat¬ astrophe. It will be noted from the depth of the fill that it will reduce extreme differentials far in excess of the reduction in maximum flood heights claimed for the Jadwin plan, and at least the major portion of it is an absolute essential whether or not the Missouri floodway is con¬ structed. Recommendations of C. E. Smith Report Concurred In. FILLING OF LOW AREAS We recommend the raising of all low areas within the city to an elevation level with established street grades, except at some points where that height will not provide a sufficient covering over sand boil areas or will not give enough stability to the inside levee slopes, where the filling should be carried higher behind the levees. SUMMARY FOR CITY. Original City. First Addition . Third Addition . Fourth Addition . Fifth Addition . Fairground Addition . Feuchter and Lansden 1st Addition. Feuchter and Lansden 2nd Addition Edgewood Park Addition. Hooker’s Addition . Burgois Addition . Miller’s Addition . Farrell’s Addition . Miscellaneous Property, west side. . City Property—Streets, etc. Miscellaneous Property, north side. . Total 201,100 764.950 51,850 60,800 267,200 3,850 34,400 19,050 10,450 9,300 27,300 76,350 12,700 1,049,050 382,700 178.950 cubic yards cubic yards cubic yards cubic yards cubic yards cubic yards cubic yards cubic yards cubic yards cubic yards cubic yards cubic yards cubic yards cubic yards cubic yards cubic yards Total yardage .3,150,000 cubic yards In the Goose Pond area in the drainage district, seep water reached elevation 30.2 City datum this year. The filling of that area to seep water height is almost compulsory and the yardage noted below is cal¬ culated on that basis: 184 FLOOD CONTROL RETORT. CAIRO DRAINAGE DISTRICT. Filling in Goose Pond Area calculated to 1922 seep water height, elevation 30.2 City Datum. Cubic Yards Owner. Required C. C. C. and St. L. R. R. between north city limits and Logan property. .. 352,000 Future City Blocks and Streets. 432,000 C. C. C. and St. L. R. R. leased to Chicago Mill and Lumber Company. ... 12,760 J. T. Logan property. Goose Pond. 453,600 Total yardage .1,250,750 TOTAL YARDAGE TO BE HANDLED. In City of Cairo.3,150,000 cubic yards In Drainage District, Goose Pond.'..1,250,750 cubic yards Grand total .4,400,750 cubic yards Some modifications might advisedly be made in some of these items as listed in the Smith report, but a careful inspection with this report in hand indicated that the coverage was well worked out not only to provide a sufficient coverage to eliminate the sand boil evil, but to mate¬ rially improve seep water conditions. The Smith report considers the hydraulic fill method, which is unquestionably the correct and economic method, but the cost figures are based upon a single plant and a five-year program. The hazards are such that the work should not extend over so long a period, but should either be contracted for or provided with plant installation on a basis of completing this entire work in two years. In view of this fact the estimate of cost should be raised to 25 cents per cubic yard, making a total cost for filling of about $1,100,000. Second: All earthen levee sections should be enlarged to the standard section now recommended b}^ the Chief of Engineers. All of this presumes that caving or sliding banks along both Ohio and Mis¬ sissippi River fronts will be protected by revetment or other bank sta¬ bilization works. ARMY PLAN FAILS TO PROTECT AGAINST GREATEST HAZARD AT CAIRO. It will be noted that this work, classified as emergency work and immediately necessary, as was evidenced by the extremely serious sand boil situation which obtained during the 1927 flood, and without which there can be no feeling of security in the City of Cairo during major river floods, forms no part of and is not included in the Army or Jadwin plan for flood control. Notwithstanding that these conditions approximated the safety limit in 1927 when the stage was only 56.4, and that in recognition of that fact and when there was no impending danger of the overtopping of the levee, the removal of all women and children from the city was seriously contemplated, the army plan, even if 100% effective, would submit this city to the additional hazard of stages as high as 59 feet without the provision of any remedy against this menace, which is more feared by the citizens of Cairo than any other. Both the location of the sand boils and the geological formation clearly indicate that heavier levee sections alone will not eradicate this evil. Cairo stands in as much probable danger from this cause as it MISSISSIPPI AND OHIO RIVERS. 185 does from overtopping of its levee system. No flood of record has oc¬ curred which would have overtopped her levees, but the sand boil evil has repeatedly reached proportions which taxed her resources to com¬ bat with stages which lacked from 3.6 to 6 feet of reaching the levee top. Only a program which would reduce the maximum flood plane below 55 feet on the gauge could be considered as making Cairo rea¬ sonably safe without raising of the lower city areas, and even then some filling over areas of thin top cover would be advisable. REDUCTION OF FLOOD LEVELS. It will be conceded that if economically practicable the ideal solu¬ tion of the flood protective problem at Cairo would be by a reduction in flood levels sufficient to require no raise in levee grades. EFFECT OF WINDSTORMS ON FREE-BOARD REQUIRED ON EARTHEN LEVEES. It is the concensus of opinion of every engineer with active personal experience in combatting floods during windstorms on the lower Mis¬ sissippi River that less than a three-foot free-board in an earthen levee constitutes an invitation to disaster. In 1920 with a 30-mile gale, a stage of only 51 feet, an effective free-board of seven feet with a thick¬ ness of levee of 44 feet at the water surface, it took a force of 200 men to withstand a wave attack along a front of only 1400 feet, and when the wind subsided, only from 12 to 15 feet of the 44-foot thickness at the water surface remained. In 1913, with a wind velocity much less, and only a two-foot free-board, several hundred men concentrated on a quarter of a mile of levee line were unable to avert a breach in the Missouri levee at Medleys. In 1927, a 20 to 28 mile gale, lasting 18 hours, cut levees with free-board of from four to seven feet several feet beyond the center line, notwithstanding a constant force of from 250 to 300 men to the mile of levee under attack. In 1920 the waves snapped 4x6 uprights like kindling wood. Only the man who has combatted wave action on earthen levees during a sustained 30-mile gale has any conception of the severity of that attack. Considering the section proposed in the army report, a 3-foot free¬ board applied to the maximum section would give a thickness at water surface of 42 feet. Considering that this territory is subjected to ter¬ rific windstorms almost annually, that they have occurred during the high water season, that a considerable portion of the Cairo levee system is of earth and will so remain, and considering the special hazards in¬ volved, it would appear that the minimum free-board which can be applied to standard earthen levees in this locality, and provide a rea¬ sonable factor of safety at points where hazard to life exists, is three feet. MINIMUM REDUCTION IN FLOOD PLANE REQUIRED TO MAKE PRESENT CAIRO LEVEE GRADES ADEQUATE. The predicted maximum possible flood is 66 feet (Revised Army figures, 65 feet). The required reduction in flood plane to provide a three-foot free-board at Cairo would be nine feet. The proposed reduc¬ tion of six feet in the Army plan would, if accomplished, leave not an 186 FLOOD CONTROL REPORT. inch of free-board (Revised Army figure is one foot) against the maxi¬ mum flood, and is therefore untenable—it would be a miracle if dis¬ aster were averted and certainly no such hazard should be applied to- city areas. It is therefore respectfully submitted that the minimum reduction in flood plane which would of itself make present levee grades at Cairo adequate is nine feet. PERMANENT PROTECTION. It has been generally considered that several alternative methods may be applied in the protection of the City of Cairo, three of which are most frequently mentioned and will be considered herein. A. A reduction in maximum flood plane to the extent that the present protective works will suffice. B. An increase in levee grades and sections sufficient to give the city a safe free-board above the maximum flood. C. A joint program of raising and strengthening the levee suffi¬ ciently to provide a safe free-board above the maximum flood plus sufficient filling in and rehabilitation of the lower city areas as wall preserve a safe equilibrium between flood plane and city grade and eliminate the sand boil evil. CAN LEVEE GRADES BE RAISED AT CAIRO ? We must differ with any conclusion that either a 30, 40, or even 50-foot levee is unsafe regardless of section. To agree with such con¬ clusion would be to condemn every existing earthen dam of over 30, 40 or 50 feet in height as an unsafe structure. We do not believe that it is the element of safety which now operates to limit levee heights along the Mississippi River, but the element of economy instead. That levee heights are, along some reaches of the river, approaching their economic limit, may be conceded, and it is quite evident that the Tensas basin floodway is included in the plan not so much as a safety require¬ ment as of a measure of economy. The proposed five-mile floodway in Missouri alone will not protect Cairo without a raise in levee grades. As already cited herein, no re¬ duction of less than nine feet in maximum flood plane can provide Cairo with a safe free-board of three feet on her earthen levees if their grade is held at 60 feet. But such a reduction in flood plane is clearly with¬ out the limits of economic feasibility. NOT PROHIBITIVE IN COST. While the readjustment of railway tracks, building rehabilitation and the raising of the concrete wall for the concrete wall section along the Ohio River front presents some problems of a different nature from ordinary earthen levee construction through agricultural districts, they are not of a difficult nature, nor, for such a moderate raise in grade as may be found necessary, prohibitive in cost. The estimate of the Gov¬ ernment engineers of $3,070,000 for a six-foot raise in grade of the entire citv svstem is indicative of this fact. MISSISSIPPI AND OHIO RIVERS. 187 THREE-FOOT RAISE IN LEVEE GRADE PRACTICABLE. Nobody will seriously question the practicability of a three-foot raise in the Cairo levee system with suitable levee sections and the filling in of the low areas in the city and industrial district to the extent rec¬ ommended herein, which, while it would reduce the extreme differen¬ tials between city levels and levee grades from six to seventeen feet, would not involve any rehabilitation costs of consequence, as was clearly shown in the Smith report. ECONOMICAL AND ADVANTAGEOUS TO CAIRO. Such a program would give the City of Cairo an assured free¬ board above even the possible flood and a greater factory of safety against any flood plane than the Army plan alone. It further pos¬ sessed the flexibility required in that, if the free-board on the earthen levee sections appear inadequate, a two-foot raise in these sections can be made at a comparatively nominal cost and the concrete wall, where less free-board is required, left at a lower grade. When the entire cost of a six-foot raise in the City’s levee system was estimated at $3,070,000 (Engineering News-Record, February 23, 1928), it is evident that this plan will not be prohibitive in cost. AUTHORITY OF GOVERNMENTAL AGENCIES TO REDUCE DIFFERENTIAL BY FILLING. The question may arise as to the power or authority of the execu¬ tive agencies in charge to include in the plan such an item as the fill¬ ing in of the low areas in the City of Cairo and its industrial district to the extent recommended and required to establish what will be beyond a doubt a safe equilibrium between city levels and maximum flood plane. The purpose of the act is stated to be for the control of floods, but the word “protection” occurring in the act indicates clearly that the pur¬ pose of such flood control is to provide protection. The act does not restrict the executive agencies to any particular method of securing the desired results and certainly no court would construe that they do not hold authority to use both the most effective and most economic method of accomplishing such results. We believe that any such objection would be swept aside by the courts as a mere quibble and contrary to the intent and purpose of the act itself. It is suggested that in the improbable event that the law should be so construed to prevent the federal agencies from doing this work, the State of Illinois could just as consistently participate in the cost of same as it could in the expense of repairing the levees after the 1927 flood. WILL REDUCE PUMPING COSTS AT CAIRO. It is deemed to be beyond the financial ability of the City of Cairo to participate in such costs; it will require such resources as they can command to provide rights of way for the enlarged levee sections. No detailed estimate of cost of this right of way is as yet available, but it will not be materially increased by a three-foot raise in grade. In ad- 188 FLOOD CONTROL REPORT. dition to the provisions of rights of way it will devolve upon the city to maintain and operate its pumping equipment, which is an indis¬ pensable necessity to any city or area surrounded by a ring levee. While the work proposed will tend to materially reduce the amount of seep water pumpage, it will not by any means eliminate that necessity, nor can it be eliminated unless and until the entire city is filled to a grade above the flood plane. ADDITIONAL DRAINAGE REQUIREMENTS. While considerable improvement has been made in the arrange¬ ment of the city^s drainage pumps and one unit added since 1922, the present installation, consisting of one 18-inch and four 20-inch centri¬ fugal pumps, all electrically driven, either direct of through belts, seep water levels averaged a foot higher in 1927 than in 1922. Although additional pumping capacity will undoubtedly ultimately be required, the immediate requirement is a revision of the sewer system to the end that the maximum performance can be had from the existing installa¬ tion. The existing leads from some of the outlying heavy seepage areas are too small to relieve the area, and capacity of pumping units exceeds the rate of delivery to them to such an extent that only intermittent operation is possible. A general revamping and reconstruction of much of the mileage of the city^s drainage sewers with features of construc¬ tion which will tend to prevent sand infiltration, minimize water ham¬ mer, and permit continuous operation during pumping periods appears necessarv before satisfactory drainage conditions can be maintained dur- ing prolonged high water stages. We do not hold with the C. E. Smith report that lowering of ground and seep water levels by increased pumping will reduce flood hazards at Cairo. Such action is undoubtedly necessary to maintain satisfactory living and health conditions, but does not relate to the problem of river flood control, except to the extent that the elimination of present water cover during floods through increased pumping will, unless such areas are earth filled to such degree as to maintain at least the same equilibrium as that which obtained from the water blanket thus removed, actually increase such flood hazards. The matter of drainage being therefore a municipal rather than a problem of river flood control, any detailed discussion of such prob¬ lem is without the scope of this report. It is well to call attention to the fact, however, that unless there is a substantial filling of the low seep water areas, the city is precluded from affecting material improve¬ ment in flood-time seep water conditions through danger from an in¬ creased flood hazard resulting from a decrease in the counter-balancing effect of the seep water blanket. OHIO WATER FRONT TREATMENT. The raising of the existing concrete wall along the Ohio water front a matter of three feet presents no serious or unusually expensive construction difficulties. It is deemed essential that all basements along this frontage be abandoned and filled, and desirable from a commercial standpoint that landside fill should be raised at least an equivalent if MISSISSIPPI AND OHIO RIVERS. 189 not a greater amount, preferably to the height of the present wall. Such filling would require a considerable amount of building rehabilitation along this frontage, the cost of which would be largely, if not wholly, compensated for by increased commercial advantages. PROBLEMS AT MOUNDS AND MOUND CITY- 1927 FLOOD AND PRESENT CONDITIONS. In the 1927 flood the City of Mounds was flooded by Mississippi River water finding its way from the Mississippi River across the Cache River basin into the Ohio River, these flood waters not only flooding the City of Mounds, but also surrounding and encircling the town of Mound City. This latter town was not flooded, being protected by its ring levee. Due to the work done since the 1927 flood, after flood gates are provided at drainage openings, such condition will not occur again for river stages against which the present levee grades are effective. The sub-grade of the Illinois Central main line tracks which protect the town of Mounds on the north and west, together with Illinois State Highway No. 2 and a short connecting link of levee between that highway and the Illinois Central embankment just south of Mounds constructed by the State of Illinois, will protect Mounds and Mound City on the south and west. FLEXIBILITY OF PLAN. While these improvements, including the circle levee around Mound City, will be effective in protecting these two towns only r gainst con¬ fined floods which do not overtop them, which means floods of less than 58 feet at Cairo, all of the levees are of moderate height and can be increased in height and section to provide protection against any flood. This leaves a considerable area between Mounds and Mound City and north and west of State Highway No. 2 subject to flooding by back water from the Ohio River, but State Highway No. 147, being constructed north from the eastern limits of Mound City, to the same grade as State Highway No. 2, will provide, after flood gates are pro¬ vided at drainage openings, equivalent protection for this area within which is located the national cemetery. Thus some eight miles of levee structures, all of which, with the exception of the short connecting link at Mounds between State Highway No. 2 and the Illinois Central em¬ bankment, is occupied either by railroad tracks or a state road, will, with properly adjusted grades and sections, provide completely effective pro¬ tection to the towns of Mounds and Mound City and the area between. NON-INTERFERENCE WITH HIGHWAY SURFACING AND R. R. TRACKS. Levee grades and sections can be increased to the extent found necessary by riverside enlargement without any interference either with the railroad tracks or highway surfaces. This by reason of the fact that the present grade is sufficiently high that it will constitute a per¬ fectly safe banquette and the probable limited raise in levee grades which may be found necessary above it will not require any modifica¬ tion in banquette section. 190 FLOOD CONTROL REPORT. CACHE FLOODWAY PRESERVED. This plan now in effect leaves the Cache River open, thus leaving an open floodway between the levees protecting the areas north and east of the Cache River and the levees of the Cairo Drainage District, through which flood waters may flow unobstructed from the Mississippi into the Ohio or vice versa. This seems to be a very desirable feature since, within the limit of its effectiveness it will tend to equalize the conditions between the two rivers and especially to relieve a congested condition on the Mississippi side when subjected to unbalanced flood loads as in 1927. There appears to be a material advantage to the City of Cairo in retaining the Cache River flood-time cross connection as an equalizer between the two rivers, and it should not be closed, unless a further detailed study of the situation should determine its effects to be nominal. It appears that the solid embankment approaches of the Cache bridge on State Highway No. 2 have encroached upon this Cache floodway to the extent that they may be difficult of maintenance, al¬ though they will have no important effect upon flood levels. PROTECTIVE WORKS WITHIN SCOPE OF MAIN RIVER IMPROVEMENTS. With the exception of that portion of the levee system which will be included in that portion of State Highway No. 147, extending north from Mound City, and the Ohio River front levee of Mound City itself, all of this levee line on the north and west side of Cache River is nec¬ essary as a protection against headwater overflow from the Mississippi River and is properly a component part of the flood control improve¬ ments of the main river. The only portion of the protective works which can conceivably be classified as coming within the “tributary” clauses of the flood control act is that reach of levee extending along the Ohio River front at Mound City and north from Mound City along State Highway No. 147 to the hills. PRESENT PROTECTIVE WORKS AT MOUND CITY. Mound City is protected by a ring levee about miles in total length, with a grade approximately equivalent to a corresponding Ohio River stage of 60 feet on the Cairo gauge, with crown widths averaging 10 feet and side slopes varying from 2 to 1 to 3 to 1. While this levee has had some emergency repairs since the 1927 flood, that reach of the levee extending from State Highway No. 147 to the Ohio River bank and along the Ohio River front is very deficient in section and a sub¬ stantial increase in section would appear to be imperative. ENCROACHMENT OF MANUFACTURING PLANTS UPON LEVEE. Unfortunately almost the entire river front, immediately behind the levee, is occupied by a number of manufacturing plants, mostly stave mills, veneering mills or other woodworking plants which are not only built immediately against the levee but encroach upon it. One of the sequences of such action is to be seen in the very steep landside slopes immediately opposite these plants resulting in unusually deficient levee cross sections. The prosperity of the city depends almost entirely upon the continued successful operation of these plants, as they constitute practically its only industries. MISSISSIPPI AND OHIO RIVERS. 191 RIVERSIDE ENLARGEMENT POSSIBLE NORTH FROM RAILROAD AVENUE. The present levee along this reach averages about 12 feet in height. A short section of the levee, between 400 and 500 feet in length, south of Railroad Avenue, is protected with a concrete wall which extends from two to three feet above the top of the earth embankment. There is also a concrete core wall flush with top of levee extending some 800 feet north from First Street. Considering the reach north from Railroad Avenue there is ample room for riverside enlargement to adequate cross-section. This will involve, however, the removal of some loading sheds between Railroad Avenue and Second Street and of the power house and one of the woodworking shops of the veneering mill located in the block south of Fourth Street, which structures are all on the riverside of levee. All of these manufacturing establishments on landside of levee should be required to remodel to the extent of non-encroachment upon the levee structure itself. LANDSIDE ENLARGEMENT NECESSARY SOUTH OF RAILROAD AVENUE. Along the reach of this levee extending south or down river from Railroad Avenue to the point where the levee leaves the Ohio River bank and turns south, being a distance of some 2000 feet, no riverside enlargement is possible and a substantial landside enlargement is im¬ perative. Immediately adjoining and encroaching on this levee on the land- side is a saw mill and woodworking plant which will have to be moved to permit of this landside enlargement. It is along this reach that a portion of the concrete wall extends and the river bank has scoured away to the extent that buttress footings of the concrete wall have been exposed, although the footings of the wall itself, from the best informa¬ tion obtainable without boring test, extend some eight feet below. RIVER BANK SCOUR. While there is evidence of very considerable river bank scour along this particular reach and some rip-rap has been placed in an attempt to stop it, it is not a caving bank and would appear to be susceptible of effective local remedial treatment by additional rip-rapping or by retards or short deflecting hurdle dikes above. Apparently the scour has been due to deflection of current into the bank at this point through the influence of certain dikes constructed on the Kentucky bank above. The correction of this condition apparently comes within the scope of channel improvements and will undoubtedly be taken care of by the governmental agency holding such jurisdiction. It is mentioned, how¬ ever, because it will need attention in the near future, although it does not constitute any immediate menace to the stability of the levee. The city drainage and seep water is cared for during river flood stages by drainage pumps. We have not investigated the adequacy of the pump¬ ing equipment as not being within the province of this report. 192 FLOOD CONTROL REPORT. PROBABLE COST. Although some special structures such as concrete riverside toe walls and possibly some concrete retaining walls on the landside where manufacturing plants are located may be found advisable or necessary when a detailed plan for the improvement of this Ohio front levee is worked out, it is improbable that such details will involve any expendi¬ tures of magnitude. The two expensive features will be the acquire¬ ment of necessary rights of way for landside enlargement and the trans¬ porting of the material with which to make the enlargement, as no pits are available opposite the work and it will therefore be a haul-in job. Prevailing Ohio Kiver stages do not indicate any available source of supply from which material could be economically placed in the levee section by the hydraulic method. If such were found practicable on the riverside enlargement reach, a concrete toe wall would be required along a considerable portion of the reach to limit the slope of the hydraulic dredged material within the area available. Koughly approx¬ imated, the enlargement and rehabilitation of this reach of levee, includ¬ ing the connecting reaches along Trinity Slough and on the north to State Highway 147, may cost from $150,000 to $100,000 if constructed to the maximum section recommended in the report of the Chief of Engineers, which should certainly be used on city fronts. Eight of way costs may appear high, but some 175,000 cubic- yards of material is involved, including special structures and unit costs will be high. Without a detailed knowledge as to just what occupancy by the vari¬ ous manufacturing plants is held by fee title it is impossible at this time to closely approximate right of way cost. LEVEE MILEAGE IN THIS PROTECTION UNIT. With the completion of the levee along State Highway No. 147 north from the eastern limits of Mound City to the hills, it does not appear that it will be necessary to maintain the back levee at Mound City or that part of same which lies to the north and west of said high¬ way, although it could be maintained by the city as emergency protec¬ tion if so desired. Eliminating this back levee will give a total levee length from Mounds to the hills north of Mound City, including the levee line along the I. C. Eailroad embankment, State Highway No. 2, State Highway No. 147, the Mound City Ohio Eiver front levee, and that reach of the Mound City ring levee extending from State High¬ way No. 147 along the north bank of Trinity Slough to connect with the Ohio Eiver front levee, of approximately eight miles. Of this eight miles, four miles, extending from Mounds to the Ohio Eiver front levee at Mound City is chargeable to protection from Mississippi Eiver flood water and the remaining four miles to back water protection. Of this latter four miles, one and one-half miles is along the Mound City frontage and two and one-half miles along State Highway No. 147, extending north from Mound City to the hills. The whole forms a loop extending north from hills at Mounds south to the Cache bot¬ toms, then along the north line of these bottomlands and the north bank of Trinity Slough to the Ohio Eiver, thence along the river bank MISSISSIPPI AND OHIO RIVERS. 193 past the town of Mound City and north to the foothills. The protected area, including the towns of Mounds and Mound City, is approximately six square miles and constitutes a self-contained flood control unit which cannot be flooded by the failure of any levees except its own. ADVISABLE ADDITIONAL LEVEES. The present protective works for Mounds and Mound City and in¬ tervening territory, even when completed, will leave an area of some 40 or 50 square miles lying south of Fayville and Olive Branch and west of Mounds unprotected, and this does not include what is known as the “Dog Tooth Bend” area to the south, which it is deemed eco¬ nomically unfeasible to protect. The protection of this area to the west, while presenting no con¬ struction difficulties, would involve the closure of the Cache cut-off be¬ tween the Mississippi and Ohio Rivers, with its equalizing effects on the two rivers. In 1913 the flood waters crossed from the Ohio to the Mississippi and in 1927 the process was reversed, the Mississippi water flowing across to the Ohio. Nevertheless, this would seem to be the constructive thing to do. The Mounds-Mound City loop would have to be maintained as a pro¬ tection against Ohio River backwater, but less increase in grade and sec¬ tion would be required to adequately serve that purpose. Under pres¬ ent conditions and without a levee to the west shutting off Mississippi River flood waters from these levees, their grade should be raised a matter of from two to three feet to provide a safe free-board against the maximum possible flood. Some less raise than that might be re¬ quired towards the Mounds end of the loop if the west levee were con¬ structed, but the difference would be nominal. MISSISSIPPI RIVER LEVEES WEST OF CACHE RIVER. Two alternative routes are available for the protection of that por¬ tion of Alexander County lying south of the C. and E. I. R. R. and north of the Cairo Drainage District. One route would be to follow proposed State Highway No. 150, which parallels on the east side the Mounds-Olive Branch line of the I. C. R. R. from Cache to Olive Branch, utilizing the highway em¬ bankment as a levee from the point where it leaves the Cairo Drain¬ age District to Olive Branch. This would involve some minor drain¬ age diversions, but is generally a good levee location and except at the southern end would not require any high levee. Another exception would be at the crossing of Lake Creek and another slough just south of it where some high fill would be necessary over unstable soil. The total length of this levee line would be about seven and one-half miles and it would add about 25 square miles to the area protected against maximum floods. The other route would be to construct a riverside enlargement of the embankment of the Cairo and Thebes branch of the Missouri Pacific R. R. Co. from Beech Ridge to Fayville, with a short connection at Beech Ridge over to the M. and 0. levee of the Cairo Drainage District. This —13 F C 194 FLOOD CONTROL REPORT. would involve about 113/2 miles of construction as compared with 7^ miles of the Highway 150 route, but it would protect approximately 20 square miles of additional territory, included in which is the Horse Shoe Lake State Park, and would also afford protection to a considerable additional mileage of improved highways as well as the Missouri Pacific tracks from Fayville to Beech Ridge. This levee would not neces¬ sarily follow the railroad throughout, but deviate to the west to follow the crest of the ridge to the north and west of Miller City. It has the further advantage of non-interference with the natural drainage to Horse Shoe Lake and in spite of the fact that it is about four miles longer is the preferable route of the two. WITHIN JURISDICTION OF MISSISSIPPI RIVER FLOOD CONTROL PLAN. This levee from the Cairo Drainage District Levee near Beech Ridge to Fayville would constitute a main river levee under the pro¬ visions of the flood control act and no local contributions would be re¬ quired other than rights of way, which item the territory affected could easily take care of. The levee should be constructed and it is respect¬ fully suggested that the State of Illinois request that it be included within the flood control plan. CONCLUSIONS AND RECOMMENDATIONS. 1. That a 66-foot confined flood at Cairo as the maximum possible flood may be considered a safe assumption. 2. That an economically justifiable program would protect cen¬ ters of population against the greatest possible flood and agricultural areas against the greatest probable flood. 3. That to provide a safe free-board for earthen levee sections against the maximum flood with no raise in levee grades at Cairo will require a reduction in elevation of maximum flood plane of nine feet. 4. That a reduction in extreme differentials between city levels and levee grade at Cairo is imperative and that a certain amount of fill¬ ing in of the lower areas is necessary to establish a safe equilibrium. 5. That, whether or not the Missouri Bird^s Point-New Madrid floodway is constructed the Cairo levees should be raised. Additional flood protection measures recommended are therefore: 1. The filling in of low areas in the City of Cairo and its indus¬ trial district to the extent of 4,400,750 cubic yards for the purpose of reducing the extreme differentials of 27 feet between city elevation and levee grade to not to exceed 20 feet, as compared wdth the modified grade, substantially along the lines of this report. 2. That the low area in the City of Cairo and in the industrial part of the Cairo Drainage District be filled by the hydraulic method in substantial accordance with the recommendations of the C. E. Smith report, involving a total quantity of 4,400,750 cubic yards with little or no rehabilitation cost. (The filling recommended is itemized in this report.) 3. That the controlling levee grade for the Cairo grade point be fixed at a minimum of 63 feet on the Cairo gauge. It is deemed ad- MISSISSIPPI AND OHIO RIVERS. 195 visable that the grade of the earthen levee sections protecting the City of Cairo be raised two feet above this controlling grade. 4. It is understood that the present orders of the War Depart¬ ment required the lowering of the central 3000 feet of the solid em¬ bankment approach at the Illinois end of the Cairo-Missouri bridge a matter of ten or eleven feet. It is respectfully suggested that in lieu of such action, and as a part of the flood control plan, suitable equalizer openings be provided in this embankment and its present grade pre¬ served. SECTION III. COMMENTS AND CONCLUSIONS BY DIVISION OF WATERWAYS The Division of Waterways agrees in the main with the conclu¬ sions and recommendations contained in the report of the Berthe Engi¬ neering Company, as submitted herewith, except that a raise in grade of two feet only for earth levees is recommended as of immediate impor¬ tance instead of the higher grade proposed in the Berthe report, proper consideration to be given in the future to a further raise in grade after observations have been made as to the effect of the operation of the Bird’s Point-New Madrid floodway on Cairo gauge heights. The views of the Division of Waterways in the matter are indicated by the fol¬ lowing comments and conclusions. “the greatest possible flood” After all is said and done, flood records do not go back far enough to give sufficient data on which to base a prediction of the magnitude of the greatest possible flood. The U. S. Weather Bureau has said that a maximum flood at Cairo will occur when maximum floods in the Ohio and the Upper Mississippi meet at that point. This is con¬ sidered a remote possibility, but the maximum floods considered in the Upper Mississippi and the Ohio, although greater than has ever ob¬ tained before in either river, are based on records covering a compara¬ tively limited period of time. The Army Plan states that a maximum flood will be one of 2,250,000 to 2,400,000 second-feet, producing a stage at Cairo, if confined, to 63, which stage, it is claimed, will be reduced by the proposed Bird’s Point- New Madrid flood way to 59. To compute the exact discharge in cubic feet per second and the resulting gauge height of the confined flood at Cairo we believe to be very difficult, in view of the uncertain factors involved. In computing such a discharge, errors or differences of 10 to 15 per cent are ob¬ tained by different experts, but these differences matter little in view of the greater uncertainty involved in determining what a maximum discharge is. From time to time expert engineers have established grade lines and sections for the Mississippi River levees which they believed to be sufficient, only to have to revise their estimates and increase their fac- 196 FLOOD CONTROL REPORT. tors of safety in the light of data furnished by new and more disas¬ trous floods. The lesson to be drawn from this appears to be that a factor of safety should be introduced to cover the uncertainties, by designing flood protection works stronger than is thought necessary, in order to pro¬ tect from the expected maximum. Certainly where human life is at stake additional expenditure for this purpose is fully warranted. FREQUENCY OF THE GREATEST POSSIBLE FLOOD. When we speak of the greatest possible flood we will, of course, have in mind how soon such a flood may occur. We believe that all estimates as to the frequency of the greatest possible flood to be mere guesswork. There is nothing in the records to show that the maximum possible flood will not come within 200 years or even 100 years. We do not know whether two such floods will occur 50 years apart, and then not another one for 400 years, or whether to expect our first one 50 or 200 years hence. A present generation may know such a flood or perhaps no one now living will be alive when such a flood occurs. The fact that such a flood never has occurred in the period covered by our records does not prove it impossible. It is not believed possible, however, to go beyond a period of 100 years in designing levees and floodways for flood protection. When overflowed frequently, floodways have a habit of filling up gradually by sedimentation,, thus reducing their capacity. What may be suffi¬ cient now in the way of design may not be sufficient for the same pur¬ pose later. As time passes, however, changes in the condition of flood- ways may be noted and guarded against, additional knowledge will be gained concerning the behavior of great floods and necessary additional construction provided. CITY VS. COUNTRY AREAS—FLOOD PROTECTION. In sparsely settled areas there is a limit beyond which it may not be economical to go in providing flood protection. In fact, in many cases it is found uneconomical to protect farming lands from floods occurring once in 30 to 50 years. Conditions are changing, however. We are in a day of progress. Paved roads are being built through drain¬ age and levee districts, and better transit facilities are provided in all directions. The flooding of a protected area now not only causes a local loss, but affects the whole surrounding country. Then, too, people are demanding the right of safe living free from even the thought of a pos¬ sibility of danger. The human life hazard is being given first considera¬ tion in all areas. With densely populated city areas there can be no question of the necessity of complete protection from all possible floods. Here we have danger to human life. A great flood is on the way—no one knows how great. The flood approaches the danger line. A near-panic develops and perhaps the inhabitants must be removed to places of safety at great cost in suffering and money. Even though levees may not break, great damage has been done because of lack of confidence. Confidence MISSISSIPPI AND OHIO RIVERS. 197 —a sense of safety—to be justified, must be engendered by knowledge of safe levee construction. 1STo government could justify its failure to remove the inhabitants of a city whose levee was being washed by waves in a 30-mile gale with the water within a foot of the top. PROTECTION FROM THE GREATEST POSSIBLE FLOOD A NECESSITY OF THE PRESENT. There is a tendency to think of a disaster which may happen but infrequently, as too remote to be guarded against. We must not lose sight of the fact that no man can tell when such a disaster will take place. In the fall of 1926 a record flood occurred on the Illinois Eiver in this State. In the spring of 1927, in spite of many predictions to the contrary, a flood of equal magnitude occurred. Protection from the greatest possible flood is of vital importance to the people of Cairo today. THE bird's POINT-NEW MADRID FLOODWAY. Conceding, as we do, that every assumption and every calculation made by the engineers in the design of the Bird’s Point-New Madrid floodway has been honestly made, nevertheless it is believed that this floodway, as designed, is more or less of an experiment and that no one, today, has sufficient knowledge of the actual working characteristics of such a floodway to enable him to determine with any degree of cer¬ tainty the effect of its construction on gauge heights at Cairo. More research and experiment are needed with the Mississippi River, itself, before such a determination can be made. It is expected that, with the Army Flood Control Plan in operation, there will be opportunity to observe, under actual operating conditions, the performance of this and other floodwavs and that within a few vears onlv, knowledge will be gained which will enable such revisions as may seem advisable to be made in existing plans. FREEBOARD NECESSARY IN EARTH LEVEE CONSTRUCTION. The Army Flood Control Plan provides for the maintenance of the existing levee grade of 60 on the gauge at Cairo and by means of the Bird’s Point-New Madrid floodway for reducing the maximum pos¬ sible flood stage to 59, thus providing a freeboard of only one foot. It will be readily understood that should a flood ever reach 59 it would take an enormous amount of labor and be very costly to furnish the necessary additional protection required for Cairo’s 20 miles of levees by means of sandbags and bulkheads. In fact, should a wind¬ storm develop, it would be an impossible task. The lives of the people of Cairo should not be jeopardized in this manner. That earth levees must have a freeboard, and that the abso¬ lute minimum recognized by engineers is three feet, is a well-known fact. In the case of a citv where many lives are at stake there can be no question of the necessity of a freeboard, and three feet might reasonably be regarded as not enough. 198 FLOOD CONTROL REPORT. NECESSITY OF PROTECTING AREAS NORTH OF THE CAIRO DRAINAGE DISTRICT. In the Berthe report the suggestion is made that an area of 40 or 50 square miles, lying south of Fayville and Olive Branch and west of Mounds, be closed by a levee connecting with the Cache River Levee of the Cairo Drainage District. At the present time a cut-off exists be¬ tween the Mississippi and Ohio Rivers at this point, the flood waters flow¬ ing in either direction as determined by the relative elevation of the two streams. It is not known just what the equalizing effect of this cut-off is, but it is thought that any disadvantage arising from its closing by the proposed levee may be balanced by a saving in the cost of levees to protect Mounds and vicinity. It is believed that the protection of this area is desirable as a part of the general flood protection plan, because, in addition to protecting a large adjacent agricultural area, it would relieve to some extent the State highways and railroads, included in the area, from damage in¬ cident to an extremely high flood in the Mississippi. The Division of Waterways has not investigated the feasibility of this prospect and it is not known what difficulties in the way of pro¬ viding for stream diversion and interior drainage may exist. In the absence of additional information the project appears desirable. FILLING OF LOW AREAS OF CAIRO AND CAIRO DRAINAGE DISTRICT. It is a well established fact that the greatest menace to the City of Cairo is the danger of breaks in the levees caused by seepage and sand boils rather than breaks caused by weakness of section or over¬ topping. Several times, during flood periods, sand boils have develop- oped which, before they could be placed under control, have washed large quantities of sand from underneath levees causing dangerous set¬ tlement. In some of these cases disaster has been averted by a narrow margin. Sand boils begin to be dangerous when floods reach an elevation of 50 on the gauge, a point nine feet below the predicted possible flood height. It has been stated that the sand boil menace at Cairo will be reduced when the Army Plan is in operation, floods of lesser volume than the maximum spilling over into the Bird’s Point-New Madrid floodway through the proposed fuse-plug section, at elevation 55 Cairo gauge, causing a reduction of flood height. It is believed that as far as relief from sand boils is concerned, the effect of the floodway will be nominal and that there will still remain the possibility that a flood much less than the greatest possible flood will produce a disaster. It is recommended as necessary that the low areas of the City of Cairo and the adjoining Drainage District be filled substantially as recommended in the C. E. Smith report and that of the Berthe Engi¬ neering Company. It is believed that the work can be done economi¬ cally by hydraulic dredge. This measure is of far more immediate im¬ portance than the raising of the levees. MISSISSIPPI AND OHIO RIVERS. 199 RAISING AND STRENGTHENING LEVEES. The statement has been made that Cairo has reached the limit in levee height and that future flood relief must come through a lowering of the flood crest. It would be very desirable to protect Cairo in this manner and the Bird’s Point-New Madrid floodway is designed to do this but falls short of furnishing the dependable degree of security nec¬ essary for a city population. The common objections to higher levees in Cairo are three: 1. Associated with the higher levee idea is that of a higher flood level and the possibility of increased trouble and danger from sand boils and seepage. 2. The fear of injury to the city commercially, because high levees are thought to create a bad impression and lack of confidence as to Cairo’s safety as a business or residence location. 3. Higher levees are thought to be less secure. The first two objections will be overcome to a large extent by the filling in of the low areas of the city and drainage district as contem¬ plated. The sand boil menace will be removed or at least greatly re¬ duced and the levees will not appear as high with the low areas filled in. The second objection in any case does not seem to be a reasonable one, as higher and stronger levees should convey the impression of greater rather than less security. The third objection cannot be held valid as with a raise of two or three feet Cairo’s levees will still be lower than many of the levees along the lower Mississippi River. It is believed that the earth levees protecting Cairo, the Cairo Drainage District, Mounds and Mound City should be built to an ele¬ vation corresponding to 62 on the Cairo gauge and that security against the maximum possible flood of the Army Plan can be obtained only in this way. This raise in levee elevation is believed necessary to secure a de¬ pendable freeboard above the 59-foot stage admitted as possible. In recommending a two-foot raise no consideration is given to the need of an additional factor of safety to cover uncertainties in determination of the possible maximum flood height, either those involved in the pre¬ diction of the maximum possible flood or those included in the design of the Bird’s Point-New Madrid floodway, but it is recommended that the question of the necessity of additional security be given proper future attention. It is believed to be very probable that an opportunity will be given for engineers to judge the efficiency of the present plan by ob¬ serving its operation during minor floods. It is recommended that measures be taken to secure these data during future flood periods. In addition to raising the grade of the earth levees at Cairo, it is recommended that the section be increased to conform to the standards adopted by the Chief Engineer for similar soil conditions. Economy should not be the ruling factor in design. Cairo’s levees instead of being just safe enough should have a factor of safety. Good material for levee construction can be obtained within reasonable distance of 200 FLOOD CONTROL REPORT. Cairo but with higher stages floods will remain for longer periods against the levees and there will be greater danger of saturation and sloughing of the inside slopes. It is believed that a proper factor of safety re¬ quires a section which will retain a line of saturation of 6 to 1. A stronger section should be adopted if later soil tests demand it. The stronger section with flatter inside slopes or banquettes will also tend to lessen the danger from sand boils near the inside toe. There are no unsurmountable obstacles in the way of raising and strengthening the levees at Cairo. The Mississippi River levee of Cairo and the Cairo Drainage District, except for a short distance, can be raised by a river-side enlargement. The Cache River levee of the Cairo Drainage District can be raised by either a river-side or an inside en¬ largement. The Ohio River levee of the Cairo Drainage District for a PICTURE NO. 13. Cairo, Ill. Seawall, built by the State of Illinois in 1915, protecting the City from inundation by the flood of 1927. Picture was taken near the crest of the flood. portion of its length must be raised by an inside enlargement. Just south of the Illinois Central Railroad bridge, where slides have occurred, it may be necessary to move levee and tracks further away from the river, or adopt a special type of construction. On account of the sandy nature of the sub-soil, borrow-pits adjacent to levees are not advisable and it will be necessary to secure material elsewhere and haul it in by dump cars, utilizing the existing railroad tracks or making use of an industrial track system. On account of the advisability of protecting railroads and highways which enter Cairo from Mounds and Mound City, additional protection for these cities should be provided by river-side enlargements of existing structures, viz., the Illinois Central Railroad on the west, State High¬ way Ho. 2 on the south and State Highway No. 147 on the east. If it MISSISSIPPI AND OHIO RIVERS. 201 is not found practicable to raise these embankments to an equivalent of 62 Cairo gauge, this amount of protection at least should be provided for the two cities by constructing a new ring levee for Mounds and by raising and strengthening the levee at Mound City. THE CONCRETE SEA WALL. The concrete wall built by the State of Illinois in 1915 is believed to be strong enough to withstand the expected flood stage of 59. A plan for providing additional freeboard to' protect from wave action, either by the addition of flash boards or by the raising of the wall itself, should be adopted as a part of Cairo’s ultimate plan for flood protection. It is not believed that it will be found practicable or necessary to raise the railroad tracks on the inside of the sea wall as advocated in the report of the Berthe Engineering Company. Certain areas on the outside of the concrete wall should be filled and new revetment provided. PLOOD PROTECTION PROVIDED BY THE FLOOD CONTROL ACT OF 1928. The Mississippi River Flood Control Act of 1928 provides that the Federal Government shall furnish flood protection to the City of Cairo by paying the entire cost of strengthening the existing levees and raising them where necessary to the grade equivalent of 60, Cairo gauge. Local agencies must furnish the necessary right-of-way, remove obstructions, construct railroad and road crossings and bear all expense except that of the actual levee construction. At the present time (1929) the Federal Government is proceeding with this work. The raising and enlarging of the Mississippi River levee of the City of Cairo and the Cairo Drainage District is nearly completed and plans are being made to raise and strengthen the Ohio River levee. The cost of this work to the Federal Government, when completed, will be in the neighborhood of $1,600,000.00. Additional cost to be borne by local interests will be about $125,000.00. When the above work is completed, in order to completely enclose Cairo and the Cairo' Drainage District with a levee to the adopted grade, the levee along Cache River must be strengthened and enlarged. At the present time it is not known to what extent the Federal Government will participate in the cost of rebuilding this levee. During certain flood periods the Mississippi River flows through the Cache basin to the Ohio; therefore, it seems that this levee should be considered as a main Mississippi River levee and paid for entirely by the Federal Government. It is understood that additional levee protection is being planned for Mounds and Mound City. It is not known at the present time to what extent the Federal Government will participate in the cost of this work. ESTIMATE OF COST OF RECOMMENDED ADDITIONAL FLOOD PROTECTION. On account of the uncertainty which exists as to the amount of work which will be paid for by the Federal Government and on account of the absence of accurate surveys showing topography, the grade, section and alignment of levees, railroad embankments and other existing structures, it is not possible to estimate with any degree of accuracy the cost of the additional flood protection recommended. It is believed that the filling of the low areas of Cairo and the Cairo Drainage District as recom- 202 FLOOD CONTROL REPORT. mended by the report of the Berthe Engineering Company can be done for not to exceed $1,200,000.00. Before an accurate estimate can be made, however, of this work and of the additional cost of raising the levees of Cairo, Mounds and Mound City to the recommended grade of 62 Cairo' gauge, an accurate survey should be made. This survey should include the accurate topographic mapping of the city and low areas of the Cairo Drainage District. The estimated cost of such a survey, to¬ gether with the engineering studies and plans for additional flood pro¬ tection for Cairo, Mounds and Mound City, is $20,000.00. CONCLUSIONS, RECOMMENDED ADDITIONAL FLOOD PROTECTION FOR CAIRO, MOUND CITY AND MOUNDS. In order to provide the degree of protection necessary for a city area it is the opinion of the Division of Waterways that the Army Plan as known at present should be supplemented by the following relief meas¬ ures. 1. The low areas of Cairo and certain parts of the Cairo Drainage District should be filled in substantially as recommended by the report of the Berthe Engineering Company. 2. The earth levees only of the City of Cairo, the Cairo drainage District, Mounds and Mound City should be raised to a grade elevation corresponding to 62 feet on the Cairo gauge so as to provide a three foot free-board above the maximum possible flood anticipated by the Army Flood Control Plan. 3. All earthen levee sections should be enlarged to conform to the latest standard sections adopted by the Chief of Engineers for similar soil and sub-soil conditions. 4. It is suggested that the feasibility of constructing a levee on the east bank of the Mississippi River northward from the Cache River levee of the Cairo Drainage District be investigated and, if found feas¬ ible, that the Federal Government be requested to construct this levee as a part of the flood control plan. 5. A complete survey should be made of Cairo and adjacent areas in advance of the preparation of any final plans and estimates. SECTION IV—THE MISSISSIPPI RIVER FLOOD CONTROL ACT. (Public—No. 391—70th Congress.) (S. 3740.) An Act For the control of floods on the Mississippi River and its tributaries, and for other purposes. Be it enacted by the Senate and House of Representatives of the United States of America in Congress assembled, That the project for the flood control of the Mississippi River in its alluvial valley and for its improvement from the Head of Passes to Cape Girardeau, Mo., in accordance with the engineering plan set forth and recommended in the report submitted by the Chief of Engineers to the Secretary of War dated December 1, 1927, and printed in House Document Numbered 90, Seventieth Congress, first session, is hereby adopted and authorized MISSISSIPPI AND OHIO RIVERS. 203 to be prosecuted under the direction of the Secretary of War and the supervision of the Chief of Engineers: Provided, That a board to con¬ sist of the Chief of Engineers, the president of the Mississippi River Commission, and a civil engineer chosen from civil life to be appointed by the President, by and with the advice and consent of the Senate, whose compensation shall be fixed by the President and be paid out of the appropriations made to carry on this project, is hereby created; and such board is authorized and directed to consider the engineering differences between the adopted project and the plans recommended by the Mississippi River Commission in its special report dated Novem¬ ber 28, 1927, and after such study and such further surveys as may be necessary, to recommend to the President such action as it may deem necessary to be taken in respect to such engineering differences and the decision of the President upon all recommendations or ques¬ tions submitted to him by such board shall be followed in carrying out the project herein adopted. The board shall not have any power or authority in respect to such project except as hereinbefore pro¬ vided. Such project and the changes therein, if any, shall be executed in accordance with the provisions of section 8 of this Act. Such sur¬ veys shall be made between Baton Rouge, Louisiana, and Cape Girardeau, Missouri, as the board may deem necessary to enable it to ascertain and determine the best method of securing flood relief in addition to levees, before any flood-control works other than levees and revetments are undertaken on that portion of the river: Pro¬ vided, That all diversion works and outlets constructed under the pro¬ visions of this Act shall be built in a manner and of a character which will fully and amply protect the adjacent lands: Provided further, That pending completion of any floodway, spillway, or diversion chan¬ nel, the areas within the same shall be given the same degree of pro¬ tection as is afforded by levees on the west side of the river contiguous to the levee at the head of said floodway, but nothing herein shall prevent, postpone, delay, or in anywise interfere with the execution of that part of the project on the east side of the river, including raising, strength¬ ening, and enlarging the levees on the east side of the river. The sum of $325,000,000 is hereby authorized to be appropriated for this pur¬ pose. All unexpended balances of appropriations heretofore made for prosecuting work of flood control on the Mississippi River in accord¬ ance with the provisions of the Flood Control Acts approved March 1, 1917, and March 4, 1923, are hereby made available for expenditure under the provisions of this Act, except section 13. Sec. 2. That it is hereby declared to be the sense of Congress that the principle of local contribution toward the cost of flood-control work, which has been incorporated in all previous national legislation on the subject, is sound, as recognizing the special interest of the local population in its own protection, and as a means of preventing in¬ ordinate requests for unjustified items of work having no material national interest. As a full compliance with this principle in view of the great expenditure estimated at approximately $292,000,000, here- 204 FLOOD CONTROL REPORT. tofore made by the local interests in the alluvial valley of the Missis¬ sippi River for protection against the floods of that river; in view of the extent of national concern in the control of these floods in the interests of national prosperity, the flow of interstate commerce, and the movement of the United States mails; and, in view of the gigantic scale of the project, involving flood waters of a volume and flowing from a drainage area largely outside the States most affected, and far exceeding those of any other river in the United States, no local contribution to the project herein adopted is required. Sec. 3. Except when authorized by the Secretary of War upon the recommendation of the Chief of Engineers, no money appropriated un¬ der authority of this Act shall be expended on the construction of any item of the project until the States or levee districts have given as¬ surances satisfactory to the Secretary of War that they will (a) main¬ tain all flood control works after their completion, except controlling and regulating spillway structures, including special relief levees; maintenance includes normally such matters as cutting grass, removal of weeds, local drainage and minor repairs of main river levees; (b) agree to accept land turned over to them under the provisions of section 4; (c) provide without cost to the United States, all rights of way for levee foundations and levees on the main stem of the Mississippi River between Cape Girardeau, Missouri and the Head of Passes. Ho liability of any kind shall attach to or rest upon the United States for any damage from or by floods or flood waters at any place: Provided, lioivever, That if in carrying out the purposes of this Act it shall be found that upon any stretch of the banks of the Mississippi Kiver it is impracticable to construct levees, either because such con¬ struction is not economically justified or because such construction would unreasonably restrict the flood channel, and lands in such stretch of the river are subjected to overflow and damage which are not now overflowed or damaged by reason of the construction of levees on the opposite banks of the river it shall be the duty of the Secretary of War and the Chief of Engineers to institute proceedings on behalf of the United States Government to acquire either the absolute ownership of the lands so subjected to overflow and damage or floodage rights over such lands. Sec. 4. The United States shall provide flowage rights for addi¬ tional destructive flood waters that will pass by reason of diversions from the main channel of the Mississippi River: Provided, That in all cases where the execution of the flood-control plan herein adopted re¬ sults in benefits to property such benefits shall be taken into considera¬ tion by way of reducing the amount of compensation to be paid. The Secretary of War may cause proceedings to be instituted for the acquirement by condemnation of any lands, easements, or rights of way which, in the opinion of the Secretary of War and the Chief of Engineers, are needed in carrying out this project, the said proceedings to be instituted in the United States District Court for the district in which the land, easement, or right of way is located. In all such proceedings the court, for the purpose of ascertaining the value of the MISSISSIPPI AND OHIO RIVERS. 205 property and assessing the compensation to be paid, shall appoint three commissioners, whose award, when confirmed by the court, shall be final. When the owners of any land, easement, or right of way shall fix a price for the same which, in the opinion of the Secretary of War is reasonable, he may purchase the same at such price; and the Secretary of War is also authorized to accept donations of lands, easements, and rights of way required for this project. The provisions of section 5 and 6 of the River and Harbor Act of July 18, 1918, are hereby made applicable to the acquisition of lands, easements, or rights of way needed for works of flood control: Provided, That any land acquired under the provisions of this section shall be turned over without cost to the ownership of States or local interests. Sec. 5. Subject to the approval of the heads of the several execu¬ tive departments concerned, the Secretary of War, on the recommen¬ dation of the Chief of Engineers, may engage the services and assistance of the Coast and Geodetic Survey, the Geological Survey, or other mapping agencies of the Government, in the preparation of maps re¬ quired in furtherance of this project, and funds to pay for such services may be allotted from appropriations made under authority of this Act. Sec. 6.- Funds appropriated under authority of section 1 of this Act may be expended for the prosecution of such works for the control of the floods of the Mississippi River as have heretofore been author¬ ized and are not included in the present project, including levee work on the Mississippi River between Rock Island, Illinois, and Cape Girardeau, Missouri, and on the outlets and tributaries of the Missis¬ sippi River between Rock Island and Head of Passes in so far as such outlets or tributaries are affected by the backwaters of the Mississippi: Provided, That for such work on the Mississippi River between Rock Island, Illinois, and Cape Girardeau, Missouri, and on such tributaries, the States or levee districts shall provide rights of way without cost to the United States, contribute 33 1/3 per centum of the costs of the works, and maintain them after completion; And, 'provided further, That no more than $10,000,000 of the sums authorized in section 1 of this Act, shall be expended under the provisions of this section. In an emergency, funds appropriated under authority of section 1 of this Act may be expended for the maintenance of any levee when it is demonstrated to the satisfaction of the Secretary of War that the levee can not be adequately maintained by the State or levee district. Sec. 7. That the sum of $5,000,000 is authorized to be appro¬ priated as an emergency fund to be allotted by the Secretary of War on the recommendation of the Chief of Engineers, in rescue work or in the repair or maintenance of any flood-control work on any tributaries of the Mississippi River threatened or destroyed by flood including the flood of 1927. Sec. 8. The project herein authorized shall be prosecuted by the Mississippi River Commission under the direction of the Secretary of War and supervision of the Chief of Engineers and subject to the pro¬ visions of this Act. It shall perform such functions and through such agencies as they shall designate after consultation and discussion with 206 FLOOD CONTROL REPORT. the president of the commission. For all other purposes the existing laws governing the constitution and activities of the commission shall remain unchanged. The commission shall make inspection trips of such frequency and duration as will enable it to acquire first hand informa¬ tion as to conditions and problems germane to the matter of flood con¬ trol within the area of its jurisdiction; and on such trips of inspection ample opportunity for hearings and suggestions shall be afforded persons affected by or interested in such problems. The president of the com¬ mission shall be the executive officer thereof and shall have the qualifi¬ cations now prescribed by law for the Assistant Chief of Engineers, shall have the title brigadier general, Corps of Engineers, and shall have the rank, pay, and allowances of a brigadier general while actually assigned to such duty: Provided, That the present incumbent of the office may be appointed a brigadier general of the Army, retired, and shall be eligible for the position of president of the commission if re¬ called to active service by the President under the provisions of- exist¬ ing law. The salary of the president of the Mississippi River Commission shall hereafter be $10,000 per annum, and the salary of the other mem¬ bers of the commission shall hereafter be $7,500 per annum. The official salary of any officer of the United States Army or other branch of the Government appointed or employed under this Act shall be deducted from the amount of salary or compensation provided by, or which shall be fixed under, the terms of this Act. Sec. 9. The provisions of sections 13, 14, 16 and 17 of the River and Harbor Act of March 3, 1899, are hereby made applicable to all lands, waters, easements, and other property and rights acquired or constructed under the provisions of this x4ct. Sec. 10. That it is the sense of Congress that the surveys of the Mississippi River and its tributaries, authorized pursuant to the Act of January 21, 1927, and House Document Numbered 308, Sixty-ninth Congress, first session be prosecuted as speedily as practicable, and the Secretary of War, through the Corps of Engineers, United States Army, is directed to prepare and submit to Congress at the earliest practicable date projects for flood control on all tributary streams of the Mississippi River system subject to destructive floods which pro¬ jects shall include: The Red River and tributaries, the Yazoo River and tributaries, the White River and tributaries, the Saint Francis River and tributaries, the Arkansas River and tributaries, the Ohio River and tributaries, the Missouri River and tributaries, and the Illinois River and tributaries; and the reports thereon, in addition to the surveys provided by said House Document 308, Sixty-ninth Congress, first session, shall include the effect on the subject of fur¬ ther flood control of the lower Mississippi River to be attained through the control of the flood waters in the drainage basins of the tributaries by the establishment of a reservoir system; the benefits that will accrue to navigation and agriculture from the prevention of erosion and sif¬ tage entering the stream; a determination of the capacity of the soils of the district to receive and hold waters from such reservoirs; the MISSISSIPPI AND OHIO RIVERS. 207 prospective income from the disposal of reservoired waters; the extent to which reservoired waters may be made available for public and private uses; and inquiry as to the return flow of waters placed in the soils from reservoirs, and as to their stabilizing effect on stream flow as a means of preventing erosion, siltage and improving navigation: Pro¬ vided, That before transmitting such reports to Congress the same shall be presented to the Mississippi Eiver Commission, and its conclusions and recommendation thereon shall be transmitted to Congress by the Secretary of War with his report. The sum of $5,000,000 is hereby authorized to be used out of the appropriation herein authorized in section 1 of this Act, in addition to amounts authorized in the River and Harbor Act of January 21, 1927, to be expended under the direction of the Secretary of War and the supervision of the Chief of Engineers for the preparation of the flood- control projects authorized to be submitted to Congress under this section: Provided further, That the flood surveys herein provided for shall be made simultaneously with the flood-oontrol work on the Mississippi River provided for in this Act: And provided further, That the President shall proceed to ascertain through the Secretary of Agriculture and such other agencies as he may deem proper, the extent to and manner in which the floods in the Mississippi Valley may be controlled by proper forestry practice. Sec. 11. That the Secretary of War shall cause the Mississippi River Commission to make an examination and survey of the Mississippi River below Cape Girardeau, Missouri, (a) at places where levees have heretofore been constructed on one side of the river and the lands on the opposite side have been thereby subjected to greater overflow, and where, without unreasonably restricting the flood channel, levees can be constructed to reduce the extent of this overflow, and where the construction of such levees is economically justified, and report there¬ on to the Congress as soon as practicable with such recommendations as the commission may deem advisable; (b) with a view to determining the estimated effects, if any, upon lands lying between the river and adjacent hills by reason of overflow of such lands caused by the con¬ struction of levees at other points along the Mississippi River, and determining the equities of the owners of such lands and the value of the same, and the commission shall report thereon to the Congress as soon as practicable with such recommendation as it may deem advisable: Provided, That inasmuch as the Mississippi River Commission made a report on the 26th day of October, 1912, recommending a. levee to be built from Tiptonville, Tennessee, to the Obion River in Tennessee, the said Mississippi River Commission is authorized to make a resurvey of said proposed levee and a relocation of the same if necessary, and if such levee is found feasible, and is approved by the board created in section 1 of this Act, and by the President the same shall be built out of appropriations hereafter to be made. Sec. 12. All laws or parts of laws inconsistent with the above are hereby repealed. 208 FLOOD CONTROL REI»ORT. Sec. 13. That the project for the control of floods in the Sacra¬ mento River, California, adopted by section 2 of the Act approved March 1, 1917, entitled “An Act to provide for the control of the floods of the Mississippi River and of the Sacramento River, California and for other purposes, “is hereby modified in accordance with the report of the California Debris Commission submitted in Senate Docu¬ ment Numbered 23, Sixty-ninth Congress, first session: Provided, That the total amounts contributed by the Federal Government, including the amounts heretofore contributed by it, shall in no event exceed in the aggregate $17,600,000. Sec. 14. In every contract or agreement to be made or entered into for the acquisition of land either by private sale or condemna¬ tion as in this Act provided the provisions contained in section 3741 of the Revised Statutes being section 22 of title 41 of the United States Code shall be applicable. Approved, May 15, 1928. FLOOD CONTROL WORKS MOUNDS, MOUND CITY, CAIRO « n d ADJACENT TERRITORY FIGURE NO 4" r *c *u_ onriKM or n* rtrw n •UT’Ml (rftMCUMO COMPANY Oiwrarx MO \NCH UNDS \MillCR 'CAf Mf* POSSIBLE ALTERNATIVE LOCATION MISSISSIPPI RIVER LEVSE FioVRE NO Vi CAIRO, ILL *nd VICINITY REPORT TO ILLINOIS DIVISION OF BSR7SS KNCIXStSIYO COl?AXI CKARLSSTV'S. LO. FIGURE NO 45 I MAP CAIRO, ILLINOIS SYNBOL9 A res proposed /o be f.Hed Ee /jbhiked Ctfu Grades OOOiE ROND AREA CAIRO DRAINAGE DtCTRjCT Crete E-lOO' ne RE NO 45 u * CL- MEMPHIS DATUM APPENDIX “A.” RAINFALL STUDIES. 1. INTRODUCTION. To obtain a clearer conception of the causes which produce floods on the Illinois River, a number of flood periods were studied in detail. Since it was not feasible to study all of the flood periods which have occurred, because of the large amount of work involved, nine of the larger ones were chosen for a detailed study. The following flood periods were selected: March to August, 1892; January to July, 1893; January to June, 1898; January to May, 1900; January to April, 1904; January to April, 1913; December 1915 to February 1916; October 1921 to April 1922; and August 1926 to June 1927. The first phase of the study of each flood period was a determina¬ tion of the amount of precipitation which caused the flood. The daily precipitation records which are published monthly by the United States Weather Bureau in “Climatological Data,” were used for this purpose. Since the precipitation records previous to 1895 were not published, it was necessary to have copies of the original records for 1892 and 1893 made at the office of the Weather Bureau in Washington. To discover the effect of the concentration of tributary flow upon the floods in the Illinois River Valley, it was necessary to obtain the pre¬ cipitation over a number of the more important sub-watersheds. The tributary watersheds used are listed in Column 2 of Tables A-2 to A-10, Appendix A. In computing the average precipitation over each such watershed, the daily precipitation at each of the Weather Bureau’s rainfall stations within and adjacent to the watershed were assigned weights, based upon the location of the station with respect to the boundary of the watershed. The precipitation at each station was con¬ sidered as extending halfway to the adjacent stations. In this way each watershed was divided into a number of parts, each of which was covered by a precipitation station. The area of each part, as determined by planimeter, divided by the total area of the watershed, gave the weight to be assigned each precipitation station. These weights were expressed as percentages. In Table A-l, Appendix A, are given (1) the tributary watershed considered, (2) the precipitation stations used in computing the average precipitations over each watershed, and (3) the weights assigned each station for each of the nine flood periods studied. Since some of the stations were discontinued from time to time and new stations established, separate weights had to be used for each flood period. The average daily precipitations over each watershed were then computed by multiplying the daily precipitation at each station by the weight assigned that station, and adding the products. 211 212 FLOOD CONTROL REPORT. In order that the distribution of precipitation over the different sub-watersheds might be studied more readily, the daily values were grouped by ten-day and monthly periods and are given in Tables A-2 to A-10, Appendix A. These condensed tables show the precipitation data for an entire flood period on one sheet, thus making it easier to study the distribution of rainfall by watersheds. Table A-ll, Appendix A, has been prepared to enable the reader to determine how much the monthly precipitations listed in Tables A-2 to A-10, Appendix A, are above or below normal. The normal precipita¬ tions are given for the northern division, the central division, and for the two divisions combined. The northern division, as defined by the Weather Bureau, includes all the precipitation stations to the north of an east and west line passing just north of Peoria. The central division includes all the stations south of this line and north of an east and west line passing just north of Grafton. In computing the normal precipitations for each division, the arithmetical average of the normal monthly precipitations at the various stations was taken. The weighted daily precipitations are shown graphically in Figs. A-l to A-37, Appendix A, respectively. Also, summation curves of monthly precipitation are shown on these figures; and above them, are platted the hydrographs of river stages. The nine flood periods are analyzed in the following sections. Since the more recent floods have been the more disastrous, the floods have been considered in inverse order of their occurence. 2. ANALYSIS OF 1926-1927 FLOOD PERIOD. The flood period from August 1926 to June 1927 was very unusual, not only because of the high river stages produced, but also because of the large number of days during which the river was above flood stage. The stages reached during October at Henry, Havana, and Beardstown were the highest which have ever been recorded. During the 11-month period the river at Morris was above flood stage for 56 days; at Peoria, 186 days; at Havana, 252 days; at Beardstown, 265 days; at Pearl, 260 days; and at Grafton, 92 days. The average precipitation over the Illinois River watershed during this 11-month period was 45.90 in., which is the maximum which has ever been recorded over that watershed in a like period. The sub-water¬ sheds over which the precipitation was above the average are as follows: Iroquois River, 47.55 in.; Vermilion River, 49.24 in.; Mackinaw River, 54.01 in.; Spoon River, 48.52 in.; Sangamon River, 52.99 in.; Macoupin Creek, 55.91 in.; Illinois River, Peoria to Havana, 51.11 in.; Illinois River, Havana to Beardstown, 49.22 in.; Illinois River, Beardstown to Pearl, 53.65 in.; and Illinois River, Pearl to Grafton, 54.44 in. Al¬ though the total precipitation for this period was far above normal, the precipitations for December, January and February were below nor¬ mal, thus dividing the period into two major precipitation divisions, each of which produced extremely high stages. During August 1926, the average precipitation over the Illinois River watershed was 3.97 in., which was about 0.60 in. above normal. 213 APPENDIX “A.” Of this total, 75 per cent occurred from August 1 to August 20. The ground was dry, however, at the end of the growing period and the August rains did not cause any appreciable rises in the river below La Salle. On the tributaries small rises resulted. During September 1926, the average precipitation was 10.51 in., which is the record monthly precipitation for any month as far back as 1857. Over the following tributary watersheds the precipitation was above the average: Iroquois River, 10.76 in.; Vermilion River, 11.45 in.; Mackinaw River, 12.53 in.; Spoon River, 11.01 in.; Sangamon River, 13.14 in.; Macoupin Creek, 12.21 in.; Illinois River, Morris to Peoria, 11.01 in.; Illinois River, Peoria to Havana, 10.83 in.; Illinois River, Beardstown to Pearl, 14.10 in.; and Illinois River, Pearl to Grafton, 12.98 in. Although there were only five days in September upon which no rain fell, the major portion fell during three storm periods. From September 1-9, 5.66 in. fell; from September 10-16, 1.41 in.; and from September 19-30, 3.44 in. The first of these storms produced the greatest rise and brought the river well above the flood stage at all points. The second storm increased the stages from one to two feet; but the river had receded to about its former stage when the third storm, followed immediately by the fourth storm of 2.58 in. during the first five days of October, brought the river to its maximum crest. The record stages reached were as follows: at Henry, 18.2 ft. on October 8-9; at Havana, 23.1 ft. on October 11, which was 0.6 ft. higher than the former record of April 1922; and at Beardstown, 26.25 ft. on October 12, which was 1.15 ft. higher than the record established in April 1922. The stage of 25.0 ft. at Peoria has been exceeded only by that of 1844. The particularly excessive rains over the Mackinaw, Sangamon, and Spoon Rivers, and over the Illinois River Valley between Peoria and Pearl account in part for the flood stages in this reach of the river being greater than those above and below. As a result of the extremely high stages, the levees of the following Drainage and Levee Districts were either overstopped or broken; Banner Special, East Liverpool, Chautauqua, Kerton Valley, Langellier, Lacey, Otter Creek, West Matanzas, Hamm, Kelly Lake, Lost Creek, Meredosia, Little Creek, McGees Creek, Oakes, Mauvaisterre, Valley City, Scott County, Big Swan, Hillview, Fairbanks and Wilson. The total area flooded in these districts was approximately 100,000 acres. Although the precipitation during October was only about 1.0 in. above normal, practically all of it fell during the first week and was the direct cause of the high flood stages reached during the second week in October. Following the peak stage, the river receded very gradually until about the middle of November; but for most or all of this period the river remained above flood stage. Although the daily precipitations which caused the October flood are shown in the tables, it was thought worth while to present these data in pictorial form, and a storm map is presented in Fig. 8, (General Report) which shows by isohyetal lines the accumulated rainfall which produced this flood. 214 FLOOD CONTROL REPORT. A storm period from November 13-19 produced 2.13 in. of rain and 0.65 in. of snow (water equivalent). The snow storm came on November 17-18. The rain raised the river at Peoria from a 15.0 ft. stage on November 13 to a 21.2 ft. stage on November 21; and at Beardstown, from a 14.5 ft. stage on November 13-14 to a 19.4 ft. stage on Novem¬ ber 23. The snow which fell on November 17-18 did not melt until about November 23. The melting snow held the river at Peoria at a nearly constant stage until the end of the month; but at Beardstown, because of the discharge from the Sangamon River, the river rose to a 20.4 ft. stage on November 30. The river then fell slowly during December and January. As previously stated, the precipitation during December and Janu¬ ary was considerably below normal. Of the 1.08 in. precipitated during December, about one-half was in the form of snow, which did not re¬ main on the ground for more than a few days. Also, most of the precipitation of 1.50 in. during January was snow. The largest daily snowfall was 0.93 in. (water equivalent) on January 13. These snows accumulated on the ground until about January 28 when a warm period began which continued until about February 8. On February 4-5, a rain of 0.81 in. melted the remaining snow and caused a sudden rise in the river. At Peoria, the rise was from a 13.7 ft. stage on January 31 to a 22.6 ft. stage on February 10; at Beardstown the river rose from an 11.9 ft. stage on February 1 to a 19.8 ft. stage on February 14. If the rain of February 4-5 had occurred a week earlier at the beginning of the warm spell, or if the rain had been greater—either of which events was highly probable—the stages reached in February would have been comparable with those reached in the preceding fall. The March rainfall totaled 3.48 in. of which 2.61 in. fell between the 10th and the 20th. Although this rainfall was about 0.50 in. above normal, it was not at all unusual. A stage of 19.8 ft. was reached at Peoria on March 27, a stage of 17.6 ft. at Havana on March 28, and a stage of 20.5 ft. at Beardstown on March 28. These stages are not at all unusual for March. During April, an average of 6.51 in. fell over the Illinois River watershed. This is about 90 per cent above normal. The high stages of the last week in March were maintained by 0.94 in. of rain on April 1, and 1.88 in. from April 2-14. From April 15-21 there was 2.74 in. of rain. These rains, coming when the river was at an 18.0 ft. stage at Peoria and a 22.0 ft. stage at Beardstown, caused a maximum stage of 24.7 ft. at Peoria on April 24, a 22.0 ft. stage at Havana on April 28, and a 25.2 ft. stage at Beardstown on April 26. The stages at Beardstown, Pearl and Grafton were the second highest of record. At Peoria and Havana the floods of October 1926 and April 1922 were somewhat higher than that of April 1927. The stages on the upper river were not unusual. The river remained at a high stage for several weeks. By March 17 it had fallen to an 18.3 ft. stage at Peoria and a 19.4 ft. stage at Beardstown. These high stages were maintained by 1.34 in. of rain during the first ten days of May and 1.99 in. during the second ten 215 APPENDIX “A.” days. During the last ten days in May there was 2.53 in. of rain which caused a rise to a 24.0 ft. stage at Peoria and a 24.7 ft. stage at Beardstown on May 29. In no other year of record has the Illinois River been above flood stage as often or for as long periods. There were three extreme flood periods, one of which was the highest of record for the stretch of river between Peoria and Beardstown. None of these floods was the result of one storm period, but of a series of storm periods following each other at such time intervals as to cause progressively higher river stages. All the rainfall studies show conclusively that at least three extended storm periods, following closely upon each other, or else heavy rains falling upon accumulated snow, are necessary to cause a big flood upon the Illinois River. It is to be noted, also, that the total rainfall is not the only factor to be considered, and that the intensity of rainfall during each storm period and the time interval between storm periods are of perhaps equal importance. Since there is an endless number of combinations of these factors, it is to be expected that the same total rainfall will rarely pro¬ duce the same flood stages. 3. ANALYSIS OF THE FLOOD OF APRIL 1922. Between Havana and Valley City the stages reached in the April 1922 flood were the highest which had been recorded up to that time, ex¬ ceeding even the flood of 1844. North of Havana and south of Valley City, the 1844 stages were considerably higher than those of 1922. At Pearl and Grafton the 1922 flood stages were the highest of record, exclusive of 1844. At Morris a stage of 20.3 ft. was reached on April 12, the second highest stage ever reached. The highest stage was 22.9 ft. on January 22, 1916. The stage of 20.2 ft. at La Salle was exceeded in 1844, 1904 and 1916. The stage of 24.8 ft. at Peoria on April 15, 1922, was exceeded by those of 1844 and 1926. The 22.5 ft. stage at Havana on April 17-20, 1922, was exceeded by that of 1926 only. The stage of 25.1 ft. at Beardstown on April 20, 1922, was exceeded by those of 1926 and 1927. The stage of 23.0 ft. at Pearl on April 29, 1922, and the stage of 25.8 ft. at Grafton on April 20, have been exceeded by that of 1844 only. The precipitation above La Salle for the period from October to December, 1921, was 9.03 in. which was 2.50 inches above normal. Above Peoria, the precipitation for the same period was 8.10 in.; above Havana, 8.51 in.; above Beardstown, 8.41 in.; and above Grafton, 8.08 in. Not only was the precipitation during these three months above normal, but the distribution was rather unusual. At intervals of about seven to ten days, precipitations of from 0.50 to 0.75 in. occurred, which produced little or no flood run-off. The hydrographs during this period 210 FLOOD CONTROL REPORT. show a remarkable uniformity of flow. This means that these rains were absorbed by the ground and replenished the ground-water storage, so that by the time cold weather set in the water content of the soil was unusually high. The January and February precipitations were about 1.0 in. below normal. During the latter half of January the pre¬ cipitation was mostly in the form of snow, which accumulated on the ground. During February the precipitation was light and the tempera¬ ture unusually mild. On or about February 19 the temperature rose above freezing. By the 22d the temperature records for that month were broken at a number of stations. It was the warmest February that had been experienced in Peoria in 67 years. The temperature remained high, the snow and the ice melted, and the smaller streams began to rise. Thus at the end of February, the saturated soil had started to give up its stored water. The March precipitation was from two to five inches above normal. The average over the Mackinaw watershed was 5.65 in.; over the Sangamon, 7.39 in.; over the Vermilion, 5.59 in.; over the Illinois River Valley from Peoria to Havana, 5.12 in.; and from Havana to Beardstown the average precipitation was 6.21 in. Although the total monthly precipitation was high, the individual daily rains were not. Over the watershed above Peoria, there were only three days on which the average precipitation was more than 0.50 in.; and the largest of these was 0.80 in. Over the Mackinaw and Sangamon River water sheds the precipitations were greater. Over the Mackinaw there were four daily rains in excess of 0.50 in., one of which amounted to 1.18 in. and another to 1.05 in. Over the Sangamon River watershed 2.51 in. of rain fell on March 14 and 1.19 in. on March 19. Over many parts of the Illinois River watershed, especially the northern portion, the April precipitation was about normal. Over the Vermilion River watershed the excess was about 1.00 in.; over the Mackinaw River watershed it was 0.80 in.; over the Sangamon River watershed, 2.80 in.; and over the Illinois between Peoria and Beardstown the rainfall was about 0.50 in. above normal. There were only two days in April on which the precipitation over the watershed above Peoria ex¬ ceeded 0.50 in. These were April 10th and 11th and the total precipita¬ tion was 1.67 in. Above Havana on these two days the precipitation was 1.50 in. Over the Sangamon River watershed there were five days with precipitation in excess of 0.50 in., the maximum being 1.12 in. on April 17. The high stages at Peoria and Havana were due, therefore, to a high March and April precipitation distribution as to both quantity and time so as to produce a slow and steady rise of all the tributaries, and this caused a greater concentration at Peoria and points downstream than would have been the case if the precipitation had been more intense. The heavy run-off from the Mackinaw River watershed and from the Illinois Valley between Peoria and Havana caused the exceptional stage at Havana. The Beardstown stage was due primarily to the high dis¬ charge from the Sangamon River and also to the slow run-off from the lower river due to backwater from the Mississippi. 217 APPENDIX “A.” Whereas the 1926 and 1927 floods were due principally to the excessive precipitation, the April 1922 flood was due more to the dis¬ tribution of a more moderate rainfall. From October 1921 to April 1922 all the factors which produce spring floods acted in conjunction, and the disastrous floods below La Salle resulted. 4. ANALYSIS OF FLOOD OF JANUAKY 1916. The 1916 flood was the result of excessive January precipitation combined with a sudden thaw and the melting of accumulated snow. For the State as a whole, the average precipitation during January was more than one inch greater than during any other January of record. The average precipitation over the watershed above Morris was 4.31 in., and the heavier precipitation over the lower portion of the Illinois River watershed increased the average to 5.41 in., for the entire watershed above Grafton. The average precipitation during December 1915, was 1.75 in., which was mostly in the form of snow; but the snow did not remain more than a few days, as the warm rains removed it. The heaviest precipitation was over the Sangamon River and Macoupin Creek water¬ sheds, and over the immediate watershed of the Illinois River below Peoria. The December rains and snows maintained an 11.0 ft. stage at Peoria, a 9.5 ft. stage at Beardstown, and an 11.0 ft. stage at Grafton. On January 1 there was an average rainfall of 0.84 in. which started a rise that continued through the cold period from January 11-19. During this period, 1.50 in. of snow (water equivalent) fell and accumulated on the ground. On the evening of January 19, the temperature rose above 45 degrees and a warm rain began and continued until January 21. The total amount precipitated was 1.21 in. of which 0.84 in. fell on January 21. As a result of the rain, the melting snow and the rise in temperature, the Illinois Valley was immediately affected. Ice began to move in the streams and on some of the tribu¬ taries above La Salle it was necessary to dynamite incipient ice jams. The river at Morris crested on January 22 at a 22.0 ft. stage, which is the maximum stage ever reached at Morris. A contributing cause of this high stage was an ice jam at the Main Street bridge in Ottawa. The water at La Salle rose at an unusually high rate and from 7 a. m. on January 21st to 3 p. m. on the 22d, the river rose 11.7 feet. The crest stage of 24.0 ft. was reached on the afternoon of January 22. This is the maximum stage ever reached at La Salle. An ice jam at Henry contributed to this high stage. The flood wave reached Peoria on January 25 and the highest stage was 23.1 ft., which was the highest stage reached at that place since 1844. This record has since been exceeded by the floods of 1922, 1926 and 1927. The river at Peoria did not remain at crest stage very long, but fell slowly. The river at Havana did not crest until January 31, because of heavy rains over the Mackinaw and adjacent Illinois River watersheds during the last week in January. The crest stage at Havana was 19.5 ft. which was the highest reached up to that time. 218 FLOOD CONTROL REPORT. The crest at Beardstown was reached on February 1-2 at a stage of 20.6 ft., which up to that time had been exceeded only in 1904. The river remained at a very high stage for about ten days, and was above the 15.0 ft. stage until March 1. The crest of 19.8 ft. at Pearl was reached on February 2-3. This stage had been exceeded in 1904 and 1892. The river at Pearl re¬ mained at flood stage for about three days and then rapidly receded to a 15.0 ft. stage by February 15. The river at Grafton crested at a 23.4 ft. stage on January 31- February 1, about two days before the crest at Pearl was reached, show¬ ing the effect of local precipitation. Fortunately, the Mississippi River was comparatively low, or else the stages on the lower Illinois would have been much higher. The levees of the following Drainage and Levee Districts were breached and the districts flooded; Partridge, Hennepin, Meredosia, McGees Creek, Hartwell and Eldred. Although the January precipitation was very unusual, yet only a portion of it affected the flood on the upper river. A thaw in the last of January or the first part of February is not so very unusual and is a fact of more or less common knowledge. Also, an accumulation of 1.50 in. of snow in January is not unusual and was exceeded in several of the nine years studied. Nor is a rainfall of 1.21 in. in three days an unusual occurrence. The snow, the rain and the rising temperature from a combination which occurs periodically. It is believed that a similar combination with either greater snowfall or greater rainfall, or both, is a probability which must be considered in predicting future late winter floods. 5. ANALYSIS OF FLOOD OF MARCH AND APRIL 1913. The flood of March-April, 1913, was caused primarily by an average precipitation of 3.85 in. of rain from March 21-25, distributed as fol¬ lows: 0.83 in. on March 21, 1.04 in. on March 23, 0.71 in. on March 24, and 0.77 in. on March 25. The secondary cause was the thaw which began on March 8 and melted 0.83 in. of accumulated snow. This melting snow saturated the ground and the surface run-off produced stages of 16.7 ft. at Peoria and 13.4 ft. at Beardstown, and thus prepared the wav for the flood of the last of the month. Neither of these causes c/ would have produced a large flood by itself, but acting in combination a large flood resulted. This flood is similar in its causes to that of 1916. The accumulated snow was not a maximum and the four-day precipita¬ tion of 3.85 in. was not unusual. If the same rain had occurred a week earlier, a much greater flood would have resulted. It is believed that a considerably larger flood than those of 1913 and 1916 is highly probable in the late winter or early spring as the result of a heavy three or four day rain coming at the same time as a sudden thaw and com¬ bining with the melting of an accumulation of snow. The total rain for March and April 1913 was 7.46 in. which is only slightly above normal for these months. The maximum precipitation for these two mon:hs during the 72 years for which records are available is 10.76 in. 219 APPENDIX “A.” A more detailed analysis of the 1913 flood is given below. During the four months preceding the flood period from January to April 1913 the precipitation was much below normal. There were deficits in rain¬ fall of 0.80 in., 0.80 in., and 1.80 in. in September, November and December, respectively. In October the rainfall was 1.30 in. above normal. The deficit for the four-month period was, therefore, 2.10 in. During January 1913 the total precipitation was 2.74 in. which was about 0.70 in. above normal. As shown in Table A-5, Appendix A, which gives the ten-day summations of precipitations, the precipitation over the Iroquois River watershed was 3.37 in.; over the Kankakee River watershed, 3.66 in.; over the Sangamon River watershed above Riverton, 4.60 in.; over the Macoupin Creek watershed, 4.17 in.; and over the Illinois River watershed between Pearl and Grafton, 4.85 in. There were freezing temperatures from January 3-14. During this period 0.95 in. of snow accumulated on the ground. From January 15- 20 the temperature rose and an unusually warm period set in. This was accompanied by light daily rains, aggregating 0.50 in., which started a rise in the river; and while the river was still rising, a rain of 0.56 in. on January 20 and one of 0.52 in. on January 23 continued the rise to a stage on January 25 about five feet above the low stage existing on January 1. On January 28 it turned very cold again and continued so until February 14. During this period light snows fell, totaling 0.31 in. From February 15-22 the weather was warm, but as there was only about 0.50 in. of rain, the river fell about two feet. On February 21-22, 0.84 in. of rain fell, which resulted in a rise of from one to two feet. Another cold spell occurred from February 23 to March 7, and during this period 0.83 in. of snow (water equivalent) fell. A thaw started on March 8 and the rise started which ended in flood stages during the last of the month. While the river was rising, as a result of the melting snow, light rains, aggregating 0.37 in. fell from March 13-16. At Peoria a stage of 16.7 ft. was reached on March 17; at Havana, 13.6 ft. on March 18-20; at Beardstown, 13.4 ft. on March 21; and at Pearl, 10.0 ft. on March 16-18. Up to this time the precipitation had been below normal. The melting snow, however, had saturated the ground. On March 19 a heavy storm period set in and by March 27, 3.84 in. of rain had fallen. On March 21, 0.83 in. fell and before all of this had run off, 2.52 in. fell from March 23-25, with 1.04 in. on the 23d. It was this heavy, but in no way unusual, rain which caused the 1913 flood. The crest stages reached during this flood were as follows: at Morris, 18.3 ft. on March 28; at La Salle, 19.4 ft. on March 29; at Peoria, 22.3 ft. on March 30-April 2; at Havana, 19.9 ft. on April 4; at Beardstown 21.8 ft. on April 5; at Pearl, 20.2 ft. on April 5-9; and at Grafton, 20.5 ft. on April 11-12. A second rise on the lower, river produced a maximum crest of 21.0 ft. at Pearl on April 13. The above stages below Havana were the highest ever reached up to 1913, with the exception of 1844. At Havana the same stage was reached in 1904. The stage of 22.3 ft. at Peoria was exceeded in 1844, 1904, 220 FLOOD CONTROL REPORT. 1916, 1922, 1926 and 1927. On the upper river the stages were not exceptional. In comparing the several floods discussed it must be remembered that the flood heights of the several floods are not true indices of the comparative discharges, since, during the earlier floods, there were fewer leveed areas between Peoria and Pearl. The conditions which caused the 1913 flood were in no way unusual and are likely to recur frequently. 6. ANALYSIS OF FLOOD OF MARCH-APRIL 1904. The causes of the 1904 flood were similar to those of the 1913 and the 1916 floods, namely, high March rainfall acting in conjunction with a spring thaw. The first storm period of the flood period from January to April 1904 occurred during the last week in January. The ground water at the time was somewhat below normal. In October 1903, the precipita¬ tion was normal; during Xovember it was 1.29 in. below normal over the upper portion of the Illinois Eiver watershed, and 1.61 in. below nor¬ mal over the southern portion ; during December there was also a deficit amounting to 0.45 in. over the northern and 0.62 in. over the south¬ ern portion of the watershed. Over the northern portion there was a fair covering of snow during the latter part of December, amounting to a water equivalent of 0.50 in.; whereas over the souther portion there was little snow on the ground at the end of December. The tempera¬ ture during December was about 5 degrees below normal, which re¬ sulted in a small run-off for that month. The abnormally cold weather continued until January 20. During this time, the snow accumulation was about 0.60 in. On January 20 a two-day thaw, accompanied by 1.50 in. of rain, produced a rise in the river, varying from about nine feet at Morris to six feet at Beardstown. As shown in Table A-6, Appendix A, the precipitation was heaviest over the Iroquois and Vermilion water¬ sheds and over the immediate valley of the Illinois Eiver between Havana and Pearl. As most of the snow was on the upper watershed, the largest run-off came from that area. The flood peaks at Morris and La Salle were quite pronounced, reflecting the steeper slopes above these points. Below La Salle the effect of the flatter slopes and wider flood planes was quite evident. The maximum stage at Morris was 14.0 ft., at Peoria 16.3 ft., and at Beardstown 15.0 ft. On January 23 the temperature dropped below freezing and remained there until February 5. The cold weather had the effect of lowering the crest of the wave then passing down stream. During this second cold period, about 0.50 in. of snow accumulated on the ground. A two-day thaw set in on February 5. There was no rain, but the melting snow and ice caused a 5.5 ft. rise at Morris and a 2.0 ft. rise at Peoria, the gage at Peoria reading 16.6 ft. At Beardstown the river flowed at approximately a 15.0 ft. stage throughout February and to the third week in March. The weather turned cold about February 7 and remained below freezing until the last of the month. During this time about 1.0 in. of snow (water equivalent) collected on the surface. On the last day of Feb- 221 APPENDIX “A.” ruary, the weather moderated, and, during the daytime, temperatures of 40 to 50 degrees prevailed. The snow and ice melted, ran off, and produced a third period of high water during the first week of March. A 16.6 ft. stage was recorded at Morris on March 4 and a second peak of 15.4 ft. occurred on March 8. At Peoria there was only one crest, that of 18.5 ft. from March 11-13. This rise was caused by the melting of a comparatively small amount of snow and the liberation of a portion of the stored ground water. At Havana the river had been above the 13.0 ft. stage since January. It now rose to a 15.5 ft. stage on March 14-16. At Beardstown the river had maintained a still more uniform stage, and from March 7-21 the gage varied from 15.3 ft. by only a few tenths of a foot. The rise up to the middle of March had been caused by the usual spring thaw. During March there were only three days without rain, but most of the rains were light. From March 1-10 the total average precipitation above Beardstown was 0.45 in., of which 0.25 in. fell on March 6. From March 11-20 the total precipitation was 1.45 in., of which 0.54 in. came on March 14 and 0.57 in. on March 17. During the last eleven days of March, 3.16 in. of rain fell, distributed as follows: 0.36 in. on the 21st; 0.56 in. on the 22d; 0.35 in. on the 24th; 0.88 in. on the 25th; 0.45 in. on the 30th; 0.37 in. on the 31st; and smaller amounts on the days not listed. The result of this almost continuous rainfall was a flood stage of 20.2 ft. at Morris on March 26; at La Salle, a stage of 20.4 ft. on March 27; at Peoria, a flood stage of 23.0 ft. on March 28; and at Havana, the flood crest remained at a 19.9 ft. stage from March 31 to April 2. This prolonged stage was due to the prolonged tributary flow from the larger tributaries, par¬ ticularly the Mackinaw Kiver and Spoon River. The crest was reached at Beardstown on April 4 at a stage of 20.0; but the river was above the 19.5 ft. stage until April 10. The precipitation over the Sangamon River watershed was especially heavy. In 1904, very little drainage work had been done on the Sangamon River watershed and therefore the run-off was much slower than in 1916, 1922, 1926 and 1927. The delayed run-off from the Sangamon prolonged the flood stage at Beards¬ town. At Pearl a flood crest of 19.4 ft. was reached on April 6-7. At Grafton the flood peak was reached on April 2 at a stage of 19.9 ft. This stage was caused by the Mississippi and not by the Illinois River. The high stage of the Mississippi reduced the slope of Illinois River and increased the gage heights at Pearl and Beardstown. A second flood on the Mississippi River during the latter part of April caused a 24.0 ft. stage at Grafton. The 1904 flood was a large one as far as total discharge is con¬ cerned, and the flood stages reached were the highest which had occurred since 1844, with the exception of the 1892 flood which produced a higher flood stage at Pearl; but because of the large amount of storage avail¬ able in the flood planes at that time, the flood stages were considerably lower than in later floods which occurred after the drainage and levee districts had leveed most of the bottom lands below Peoria, thereby con¬ fining the river to a very narrow flood channel. Nevertheless, the stages on the upper river were quite high. The 1904 record at Morris was 222 FLOOD CONTROL REPORT. not broken until 1916, and again in 1922. At La Salle the 1904 stage has been exceeded only by that of 1916. The total precipitation for January, February and March 1904 was 9.33 in. This total has been exceeded twice in the 72 years of record. 7. ANALYSIS OF FLOOD OF MARCH 1900. The flood of March 1900 was caused by the melting of a large amount of accumulated snow, unaccompanied by rain, following a pre¬ vious thaw which had brought the river to about a 12.0 ft. stage at Peoria and an 11.5 ft. stage at Beardstown. These were moderately high stages in 1900. The 1900 flood is an example of an unusually large amount of snow, but no rain, causing a flood. If the March rainfall of either 1904 or 1913 had occurred in 1900, probably the largest flood in the history of the river would have resulted. The flood period from January to April 1900 was unusual in that the monthly precipitations were in no way unusual. The rainfall dur¬ ing the preceding fall was below normal. The total precipitation for September, October, November and December was 9.43 in., which was 1.34 in. below normal. Although during December there was an average of about 0.60 in. of snow (water equivalent) precipitated, it did not re¬ main long and by the end of the month the ground was bare. Because of the deficit of precipitation during the fall months, the ground-water supply was less than normal. The January precipitation was only 1.25 in. which was about 1.0 in. below normal. The temperature during the middle of the month was unusually mild and the ground-water flow started early and caused rises of from about 4.0 ft. at Morris to about 1.5 ft. at Pearl. Jan¬ uary began with cold weather and ended with cold weather, but much of the month was like spring in its warmth. On January 18 the ice in the river at Ottawa began to break up, but the river froze again on the 27th. By January 25 most of the frost was out of the ground. From January 17-27 the river rose more or less steadily. The freezing weather which set in on January 27 caused the stream to recede somewhat at all stations except Havana, where the river continued to rise slowlv. The cold weather continued during the first week in Feb- ruary and from February 3-6 about 0.70 in. of snow (water equivalent) collected on the surface. There was a warm period, February 7-8, with about 0.35 in. of rain on the 7th and 0.60 in. of rain on the 8th, small amounts in themselves, but, combined with snow, making a total of 1.58 in. which ran off very quickly and caused a 9.0 ft. rise at Morris, a 4.0 ft. rise at Peoria, and about a 2.0 ft. rise at Beardstown. Light rains from February 12-16, together with the ground water flow, maintained the river at about a constant stage. A rain of 0.50 in. on February 21 caused a small rise in the stream. On February 27 a great snow storm started and by the 28th 1.24 in. of snow (water equivalent) had fallen. This snowfall was reported as being the greatest since 1830-31. It was followed on March 5 bv 0.63 in. of snow and on 4 / March 6 by 0.44 in. of snow (water equivalent). On March 9 a thaw began and the accumulated snow, totaling 2.50 in. started to melt. The 223 APPENDIX “A.” result was the maximum flood for 1900. The Peoria gage reached 19.9 ft. on March 16; the river at Havana crested at a 17.4 ft. stage on March 18; the crest passed Beardstown on March 19 at a 17.7 stage; at Pearl the maximum stage of 16.1 ft. was reached on March 22. Table A-7, Appendix A, shows that the heaviest snowfall from February 27 to March 6 was centered over the watershed between Beardstown and Havana and over the Mackinaw and Sangamon river valleys. The run-off from this storm must have been as great as those of later years when higher stages were reached; but in 1900 the flow was not restricted by levees and the storage in the river valley was much greater. The March flood of 1900 illustrates the effect of the melting of a large accumulation of snow. If the precipitations of March 5th and 6th had been in the form of rain, the run-off would have been much more rapid and the stages reached would have been much higher. So it is evident that a much more unfavorable combination of conditions might easily have occurred. Below Beardstown the stages were lower than those above. In nearly all of the floods considered, the river at Pearl crested before the flood wave arrived from Beardstown. This will always be the case un¬ less the Mississippi is at a high stage. In March 1900 the river at Grafton crested on the 16th, which was three days before a crest was reached at Beardstown. There were two rises at Grafton during April and May. These were caused by the Mississippi. The total precipitation during January, February and March was only 7.60 in. which is only slightly above normal, but the precipitation of 4.33 in. in February was nearly 2.00 in. above normal; and it was this abnormal precipitation, largely in the form of snow, which was responsible for the 1900 flood. 8. ANALYSIS OF FLOOD OF MARCH AND APRIL 1898. The flood of the first week of April 1898, was caused by three moderate storms coming the last three weeks of March and the melting of accumulated snow. Hone of the three storms was excessive, but the accumulation of snow was much greater than normal. During the four-month period preceding January 1898, there was a deficit of rainfall amounting to about 2.50 in., and because of the unusually high fall temperature, the evaporation was above normal. The result was that the amount of water stored in the ground when freezing temperature set in was much less than normal. On January 1, 1898, there was about 0.30 in. of snow on the ground over the northern division and about 0.55 in. over the central division. January was unusually warm, the average temperature being 5.5 degrees above normal. The precipitation also was above normal and varied from 3.30 in. over the watershed above Morris to 4.11 in. over the entire Illinois River watershed. The month started in with freezing temperatures and there was little melting of snow until about the 8th. A rain of from 0.78 in. to 1.20 in. from January 9-12 melted most of the snow then on the ground. Light snows fell from January 13-15 and remained on the ground until the 20th. On that day about 1.00 224 FLOOD CONTROL REPORT. in. of rain melted the snow. The weather turned cold again and on January 22 an average of 0.83 in. of snow and rain fell. This was followed on January 25 by about 0.70 in. of snow over the northern division and rain over the central division. On January 26 a cold wave brought low temperatures which continued until February 3rd. The temperature during February was about 2 degrees above normal. There were three cold periods. The first was the continuation of the January cold wave and was the most severe of the three periods. It lasted until February 3. The second cold period was on the 15th and 16th, and the third from the evening of the 23d to the morning of the 27th. The total average precipitation during February was 2.06 in. over the area above Morris, and 2.23 in. for the entire watershed. There were only two rain periods of any moment. The first was on February 10-11 and 0.60 in. of rain fell; the second was from February 18-21 and gave a total of about 0.90 in., most of which was in the form of snow over the northern portion of the watershed. The rain on February 10-11 did not remove all the snow from the upper end of the water¬ shed. The storm of February 19-21 covered the northern part of the watershed with about 12.0 in. of snow. Over the southern part of the watershed the ground was bare most of the month. Both the temperature and the precipitation were above normal dur¬ ing March. The average temperature exceeded the normal by nearly 5 degrees. The average precipitation above Morris was 4.55 in.; and above Grafton it was 5.79 in. There were three storm periods during the month, namely 10-13, 18-22 and 26-27. During the first storm period, 1.34 in. of rain fell; during the second, 2.14 in.; and during the third, 1.94 in. The first storm produced a stage of 15.8 ft. at Peoria on March 17, a stage of 13.4 ft. at Beardstown on March 21, and a stage of 12.9 ft. at Grafton on March 15. The second storm raised the river at Peoria to a 17.4 ft. stage on March 23; at Beardstown to a 14.8 ft. stage on March 26; and at Grafton to a 17.2 ft. stage on March 23. The third storm was the most intense of the three and caused a maximum stage of 19.4 ft. at Peoria on April 1 and a stage of 19.9 ft. at Beardstown on the same day. As far as flood stages are concerned, this flood was not nearly as severe as those which have followed in later years; but it furnishes an excellent illustration of how a flood is built up in successive stages by successive storm periods. In this instance there were three such storm periods. Had there been a fourth storm, a flood comparable with those of recent years would have resulted. 9. ANALYSIS OF FLOODS OF MARCH AND MAY 1893. Complete temperature data were not available for this flood period, but at Urbana, Illinois, the main temperature for January was 14.8 degrees and the maximum temperature reached was 48 degrees. Also, the hydrographs show the river at a very low stage throughout January and well into February. The river was frozen over until about February . 12 . 225 APPENDIX “A ” The precipitation during January was somewhat above normal over the northern half of the watershed and below normal over the southern half, and below normal for the watershed as a whole. All of the precipitation, however, must have been in the form of snow, and by February 1, 2.07 in. of snow (water equivalent) had accumulated on the watershed above Peoria and 1.52 in. over the watershed above Grafton. By February 10 this amount had been increased to 3.54 in. above Peoria and 2.95 in. above Grafton. If these assumptions as to temperature are correct, the accumulated snow of February 1 was the maximum for any of the flood periods considered. Evidently a sudden rise in temperature began on February 12, and the melting snow and ice started a rise in the river. From February 13-18, 1.07 in. of rain fell over the Illinois River watershed. By February 24, the river at Peoria had reached a stage of 13.8 ft.—a rise of 9.2 feet. The river then fell about 0.8 ft. by March 1. Probably a drop of temperature was responsible for this fall. During the last ten days in February, the average precipitation above Peoria was only 0.57 in., but over the Iroquois River watershed there was 1.42 in. of rain during this period. Warmer weather during the first week in March caused a second rise from the melting of the snow which fell in January and February. The river would have crested at about a 16.0 ft. stage at Peoria on March 9, but 1.02 in. of rain on the 8th and 9th continued the rise to a maximum stage of 19.9 ft. on March 15. At Beardstown the stage was 17.0 ft. on March 14 and at Pearl the river crested at a 16.0 ft. stage on March 17. The April rainfall was over 3.00 in. above normal. During the first ten days, 1.10 in. fell, and during the second and third ten-day periods the rain was 3.19 in. and 3.10 in., respectively. These heavy rains during the last half of the month produced a flood stage of 16.5 ft. at Peoria on May 6, a stage of 16.8 ft. at Beardstown on May 5, and a stage of 18.1 ft. at Pearl on May 4. The March flood was due principally to the melting of the snow over the northern portion of the watershed, resulting in high flood stages on the upper river, but only moderate stages on the lower river. The May flood was caused by excessive precipitation during the last half of April. A study of Table A-9, Appendix A, shows that the heaviest precipitation was over the lower end of the watershed, and this fact is reflected in the hydrographs, as the river crested at Pearl on May 4, at Beardstown on May 5, and at Peoria on May 6. The flood of 1893 was the smallest, in so far as stages were concerned, of any of the nine floods considered. 10. ANALYSIS OF FLOODS OF MAY AND JUNE 1892. Both of these floods were caused by excessive precipitation. The winter snows had melted and run off and the ground moisture was normal by the end of March. The March precipitation was only 2.32 in. which is about 0.50 in. below normal. During the first ten davs of —15 F C 226 FLOOD CONTROL REPORT. April, 2.52 in. of rain fell, followed by 3.16 in. and 0.76 in. during the succeeding ten-day periods, respectively. The distribution of these rains over the watershed is shown in Table A-10, Appendix A. May was also a very wet month. During the first ten days, 3.46 in. of rain fell. Over the northern portion of the watershed the precipitation was much above this average value. The average rainfall over the Vermilion River watershed for this period was 5.72 in., and over the Illinois River Valley between Morris and La Salle it was 8.45 in. There were no gage readings at Morris and La Salle, but the flood stages must have been high. At Peoria the river rose from a 10.9 ft. stage on May 2 to a 21.9 ft. stage on May 9. The lower river did not crest until the middle of the month, during which time more rain fell. From May 10-20 an average of 2.57 in. fell over the entire watershed. These rains were very uniformly distributed over the entire area, and maintained a high stage on the river above Peoria, but produced no peak stages. Below Beardstown, however, the run-off from these rains combined with the flood wave from the upper river, due to the preceding storm, and caused high flood crests. At Beardstown the river rose to an 18.4 ft. stage on May 15, and at Pearl a stage of 20.4 ft. was recorded on May 19. This is the fifth highest stage ever reached at Pearl. Higher stages were recorded in 1844, 1922, 1926 and 1927. Although the precipitation during the last ten days in May aggre¬ gated 3.07 in., no new flood crests resulted. During June there were heavy rains over the watershed above Peoria. There was 11.89 in. of rain over the DesPlaines watershed, and the average for the watershed above Peoria was 8.66 in. High stages on the upper river was the result. The only record available, however, is that at Peoria, where a stage of 18.5 ft. was reached. The stages on the lower river were not unusual. 11. COMPARISON OF FLOOD STAGES. In order that the magnitudes of the ten floods considered can be better compared as to flood stages, Table A-21, Appendix A, has been prepared. The numbers in parentheses directly over the flood stages in¬ dicate the order of magnitude of that stage with respect to the flood stages in other years at that station. It will be noted that on the upper river the flood of 1916 produced stages from three to four feet higher than those reached in any other flood. This was due principally to ice jams. The second, third and fourth highest differ only slightly from each other. Between Peoria and Beardstown, each of the later floods produced a high stage than that preceding. This does not mean necessarily that recent floods have been greater than former ones. The principal cause of this progressive increase in flood heights is the decrease in flood- plane storage resulting from the construction of levees. In 1904 there were few leveed areas along the river, whereas in 1926 nearly all of the bottom lands below Peoria had been included in drainage and levee districts. 227 APPENDIX “A.” TABLE A-21—MAXIMUM STAGES REACHED IN TEN FLOOD PERIODS. Year. ocauon. 1927 1926 1922 1916 1913 1904 1900 1898 (6) (4) (2) (1) (7) (3) (5) (8) Morris... 19.2 20.0 20.3 22.9 18.3 20.2 19.4 16.5 (4) (5) (3) (1) (6) (2) LaSalle_ . . _ . -_ 20.1 20.0 20.2 24.0 19.4 20.4 (3) (1) (2) (4) (6) (5) (8) (9) Peoria.. 24.7 25.0 24.8 23.1 22.3 23.0 19.9 19.4 (3) (1) (2) (5) (4) (4) (7) (6) Havana..... 22.0 23.1 22.5 19.5 19.9 19.9 17.4 18.0 (2) (1) (3) (5) (4) (6) (9) (7) Beardstown.... 25.2 26.2 25.1 20.6 21.8 20.0 17.7 19.9 (2) (3) (1) (6) (5) (7) (9) (8) Pearl.... . . ... 22.7 22.1 23.0 19.8 20.2 19.4 16.1 18.3 (2) (3) (1) (4) (5) (6) (8) (7) Grafton.... 25.7 23.7 25.8 23.4 20.5 19.9 17.1 17.2 1893 ( 8 ) 19.9 GO) 17.0 GO) 16.0 1892 (7) 21.9 ( 8 ) 18.4 (4) 20.4 12. RELATION BETWEEN RAINFALL AND RISE OF RIVER. A study was made to determine the relation between rises in the river and the rainfalls which produced them. With this end in view, all the rises in the river at Morris, La Salle, Peoria, Havana and Beards- town during the nine flood periods were taken from the hydrographs and tabulated in separate tables, together with the rainfalls which pro¬ duced them. In many instances, it was uncertain as to just what rain¬ falls caused the rises and the conclusions reached and recorded were based entirely upon the judgment of the observer. Many of the dis¬ crepancies noted later are due to errors of judgment. Also, many of the spring rises were caused almost entirely by melting snow and ice, and it was impossible to determine how much of the accumulated snow had melted to produce a certain rise. Each rise in feet divided by the corresponding rainfall in inches gave the rise in feet for each inch of rainfall. This ratio was a con¬ venient basis of comparison and furnishes a means of estimating future flood heights for an assumed rainfall. These data are given in Tables A-12 to A-20, Appendix A. As will be observed there is a wide range in the ratios, although the majority are fairly uniform. The high and low ratios were expected, because of the extreme difficulty in determining the true amount of rain, or rain and melting snow, which caused a particular rise. In fact these extreme values might very justifiably have been omitted from consideration, but only two such values were omitted in computing the averages. The ratios in Tables A-12 to A-20, Appendix A, were averaged and recorded in Table A-22, Appendix A. This table also shows maximum and minimum values and the number of items used in computing the averages. It is obvious from a glance at Tables A-12 to A-20, Appendix A, that one inch of rainfall has produced greater rises during the winter and spring, than during the summer and fall months. This is entirely logical, as the frozen ground in winter and the melting snow and ice in the spring assist in producing greater rises. It was decided to include the floods from December to April in one group and the remaining months in another group for Morris and La Salle. At Peoria, Beards- town, and Havana the month of April was included in the summer group. 228 FLOOD CONTROL REPORT. Table A-22, Appendix A, is very significant. It is to be noted that at each of the five points on the river, one inch of summer and fall rains produce rises from 25 to 50 per cent less than those produced by one inch of winter and spring rains. This can be partly explained by the greater imperviousness of the ground in the winter and spring months,, due to the frozen or saturated ground. Part of the explanation, how¬ ever, lies in an underestimation of the rains which produced spring floods, as in nearly every instance some of the run-off was from rains which had fallen weeks or months before and were stored in the soil during the winter months. It is also to be noted from Table A-22, Appendix A, that as the floods progress downstream, and the tributary watershed become greater, the rise per inch of rainfall becomes less. Thus for each inch of rainfall over the watershed above Morris, an average rise of 3.71 ft. has resulted at Morris; whereas at Beardstown the average rise per inch of rainfall is only 1.93 ft. TABLE A-22—RISES IN FEET PRODUCED BY ONE INCH OF RAINFALL. Station. Season. Number of rises. Rise in feet per inch of rainfall. Maximum. Mean. Minimum. Morris_ Dec.-Apr_ 48 6.15 3.71 1.01 May-Nov_ 12 4.25 2.33 1.01 LaSalle___ Dec.-Apr... 31 5.71 3.15 1.01 May-Nov_ 13 3.61 2.16 0.60 Peoria_ Dec.-Mar.. 40 5.09 2.42 1.00 Apr .-Nov... 21 3.48 1.64 0.48 Havana_ Dec.-Mar_ 25 3.86 2.00 0.59 Apr .-Nov_ 14 4.28 1.38 0.32 Beardstown_ Dec.-Mar_ 23 3.61 1.93 0.68 Apr.-Nov_ 23 4.00 1.45 0.33 The rise in a stream at a given point is dependent upon, not only the total amount of rainfall, but also the distribution and intensity of that rainfall, and upon the imperviousness of the surface upon which the rain falls. Thus a rain of a given magnitude, falling upon frozen ground in the early spring, or at other times of the year upon ground which has been saturated by closely preceding rains, will produce a greater rise than a ram of the same magnitude falling upon the same water¬ shed when the ground is dry. Although the condition of the ground surface during each of the storm periods was known with a fair degree of accuracy, this factor was not considered in computing the ratios in Tables A-12 to A-20, Appendix A. As many of the rises considered came as a part of a more extended rise, it can be assumed that in these instances the ground was practically saturated at the be¬ ginning of the storm which produced the final rise. There was no record, however, in any of the storm periods as to the distribution of rainfall during daily periods, and the difference in the intensities of the in¬ dividual storms was the principal cause of the variations in rises through the middle ranges. When all the foregoing factors are considered, the agreement be¬ tween the individual ratios in Tables A-12 to A-20, Appendix A is as close as could have been expected. 229 APPENDIX “A.” TABLES. TABLE NO. A-l—RAINFALL STATIONS AND THEIR WEIGHTS. Based on areas covered—used in computing weighted average daily rainfall. Flood Periods. Watersheds and rainfall stations. Water¬ shed area, sq. mi. 1926- 27 1921- 22 1915- 16 1913 1904 1900 1898 1893 1892 Per cents of sub-watershed areas Iroquois above Chebanse_ 2,185 Roberts _ __ 11 11 14 Kankakee 7 8 Watseka__ _ 32 32 86 89 Hoopeston. - _ _ 14 14 19 22 22 Collegeville, Ind_ 24 30 33 33 Wheat field, Ind__ 4 5 Thayer, Ind___ 8 Martinton-- - _ 34 40 40 70 87 Rantoul_ - .._- 5 5 9 13 7 Rennselaer, Ind_ 33 Winamac - - _ 12 Strawn_ __ 6 Valparaiso . _ 3 11 Hammond - _._ 2 LaFayette _ 5 Total_ _ 100 100 100 100 100 100 100 100 100 Kankakee above Momence_ 2,395 Kankakee.. . . ___ 2 7 Thayer_ .... . _ 15 Hobart___ 3 6 Valparaiso.. 10 11 31 23 26 23 55 Wheatfield.... 12 20 Hamlet___ 18 LaPorte... 10 16 16 18 20 21 13 South Bend.. . 10 10 10 10 20 18 15 Plymouth__ _ 15 25 25 18 Goshen.__ . 2 2 Winona Lake.. 3 3 5 4 Knox. .. __ 25 25 Martinton_ _ 7 11 8 8 7 Collegeville___ 6 14 Syracuse.__ 7 7 3 Hammond. 5 8 25 Rennselaer . __ 17 Glennwood_ . . 9 Winamac. ... 12 Warsaw__ 5 Michigan City_ _ 71 39 Watseka_ _ 4 6 Total... .. _ 100 100 100 100 100 100 100 100 100 Kankakee, Momence to Cus¬ ter Park_ _ 430 Kankakee_ 100 100 Manteno___ 82 Morris_ 4 Martinton_ . 70 18 70 68 63 Joliet_ __ 26 30 20 11 Hammond_ 12 36 Glennwood_ 21 Dwight_ 5 Watseka... _ 64 94 Aurora .. 6 Total__ 100 100 100 100 100 100 100 100 100 230 FLOOD CONTROL REPORT. TABLE NO. A-l—Continued. Flood Periods. Watersheds and rainfall stations. Water¬ shed area, sq.mi. 1926- 27 1921- 22 1915- 16 1913 1904 1900 1898 1893 1892 Per cents of s ub-watershed areas. Des Plaines above Joliet_ 835 Racine.... 12 4 4 4 4 18 7 Waukegan.. 30 Chicago_ 23 23 23 25 Elgin... 17 24 24 18 6 Joliet___ 18 18 18 10 19 10 10 Antioch_ 31 31 32 36 LaGrange__ 36 26 26 42 42 St. Charles.. 16 Ft. Sheridan__ 30 22 47 47 Wheaton___ 10 13 Zion__ 22 Watseka___ 7 Aurora. _ 4 4 Waukesha..__ 7 Total___ 100 100 100 100 100 100 100 100 100 Des Plaines below Joliet_ 595 Elgin.... 16 16 16 6 4 Aurora__ 30 30 30 21 11 6 61 38 Joliet_ 54 54 54 60 54 51 47 St. Charles.. 24 25 5 8 LaGrange_ 10 28 62 Wheaton__ 26 29 Hammond.... 3 11 Oswego__ 5 Glennw r ood_ 5 Total.. 100 100 100 100 100 100 100 100 100 Illinois, Morris— /Mouth Des Plaines/ 1,135 \Custer Park. __ / Aurora. ... 5 5 5 9 28 30 Morris_ 26 26 27 22 Dwight_ 40 40 48 43 57 Kankakee _ 15 15 Joliet___ 14 14 20 7 43 45 28 Yorkville_ 10 16 Matena_ 18 Martinton_ 19 11 Ottawa_ 22 2 38 38 Hammond_ 2 15 Strawn_ _ 9 Streator_ 22 Oswego_ _ 15 Watseka__ 19 21 LaGrange. __ 11 Total__ 100 100 100 100 100 100 100 100 100 Fox above Algonquin__ 1,335 Elgin..... 8 7 7 7 11 Waukegan_ 12 Marengo___ 7 5 Williams Bay_ 40 29 Racine_ 4 11 5 Waukesha_ 29 29 38 38 38 37 30 33 33 Antioch_ 30 50 50 53 Rilev____ 5 5 6 1 5 12 12 St. Charles. _ 3 4 Ft. Sheridan.. _ 8 4 16 16 Chemung_ 32 14 Delevan___ 25 39 39 Zion..... 13 Total_ 100 100 100 100 100 100 100 100 100 231 APPENDIX “A.” TABLE NO. A-l—Continued. Flood Periods. Ref. Watersheds and rainfall No. stations. Water¬ shed area, sq.mi. 1926- 27 1921- 22 1915- 16 1913 1904 1900 1898 1893 1892 Per cents of sub-watershed areas. 8 Fny, Algonqnin-Dayton 1,135 Elgin___ 20 21 21 17 14 Sycamore . 8 9 17 7 11 15 12 20 20 Paw Paw 25 30 22 Ottawa_.._.. _ 14 25 9 20 29 24 29 29 Morris 4 16 4 Aurora_ 29 30 33 11 30 11 43 43 St. Clharles 17 25 11 24 Yorkville 28 30 Riley 3 1 2 8 8 Oswego 22 Ashton 5 Total.. 100 100 100 100 100 100 100 100 100 9 Vermilion above Streator-. .. 1,055 Minonk_ 16 16 12 12 12 21 14 Pontiac__ 58 58 51 51 71 Roberts. 26 26 26 26 Streator. .. . __ 11 11 11 20 16 Martinton.. 6 3 Strawn.. . 59 Dwight_ _ 30 Lexington. . _ 34 Rantoul 3 12 Ottawa_ ._ 28 29 Watseka_ _ 24 30 Bloomington_ 36 41 Total....... 100 100 100 100 100 100 100 100 100 10 Vermilion above month __..... 1,280 Pontiac___ 50 50 41 41 58 Roberts...... 22 22 21 21 Minonk__ 16 16 10 10 10 17 12 LaSalle__ 12 12 5 5 5 Streator_ 23 23 23 33 29 Martinton__ 4 2 2 Strawn_ 46 Ottawa..__ 2 3 43 43 Lexington... 27 Dwight_ 24 Rantoul_ 3 9 Watseka___ 19 23 Bloomington.. 29 34 Total.. / 100 100 100 100 100 100 100 100 100 11 Illinois, Morris to LaSalle_ 570 Morris.. 27 46 25 25 Dwight__ 5 5 3 3 15 Ottawa___ 38 43 42 63 89 78 100 100 LaSalle.. 21 40 26 20 26 Paw Paw_ 9 9 8 Streator__ 3 2 6 11 5 Yorkville. . 5 Ashton___ 2 Total. 100 100 100 100 100 100 100 100 100 12 Illinois, LaSalle to Peoria. 1,610 Paw Paw.. 5 5 5 Walnut... 10 10 11 10 11 15 13 37 39 Tiskilwa_ _ 18 18 18 18 18 23 41 Henry_ 30 30 30 30 30 32 Peoria___ 9 9 9 9 9 10 12 Minonk. 13 13 13 13 13 12 21 LaSalle__ 15 15 19 15 19 232 FLOOD CONTROL REPORT. TABLE NO. A-l—Continued. Flood Periods. Watersheds and rainfall stations. Water¬ shed area. sq.mi. 1926- 27 1921- 22 1915- 16 1913 1904 1900 1898 1893 1892 Per cents of sub-watershed areas. Ottawa, ._.. 6 5 27 27 Streator_ 2 2 Ashton_ _ 4 E. Peoria..... 2 32 34 Galva... ... . 4 Total_ _ 100 100 100 100 100 100 100 100 100 Illinois, Peoria to Havana_ 1,050 Peoria.... 60 60 60 60 68 65 42 Fair view. 14 14 14 14 Havana_ 26 26 26 26 32 35 33 34 34 East Peoria.. 25 66 66 Total.... 100 100 100 100 100 100 100 100 100 Mackinaw above Green Valley Peoria.... 1,120 25 25 25 25 27 26 Minonk.... 21 21 21 21 21 21 15 Lincoln.. 3 3 3 3 Bloomington... 43 43 43 43 47 38 19 60 66 Roberts... 8 8. 8 8 Rantoul... 5 6 Strawn. 15 Lexington. 36 East Peoria. 30 34 34 Total.. 100 100 100 100 100 100 100 100 100 Spoon above Seville.. 1,580 Galva. 40 36 38 37 27 26 28 53 Tiskilwa_ _ 6 6 6 6 6 6 8 Fairview. 40 35 44 29 Macomb__ 8 3 6 3 Henrv.... 4 4 4 4 5 4 Peoria_ 2 2 2 2 3 4 Monmouth. 14 19 6 6 6 Knoxville__ 34 34 32 Bushnell_ 22 19 22 40 Havana... 2 2 39 East Peoria_ 5 61 Total__ 100 100 100 100 100 100 100 100 100 Spoon below Seville 220 Fairview_ . 28 28 28 28 Havana... 34 34 34 34 50 52 64 64 100 Astoria__ 26 26 26 26 20 19 Macomb_ 12 12 12 12 Bushnell.. .. . 30 29 36 36 Total.__ 100 100 100 100 100 100 100 100 100 Illinois, Havana to Beards- town_ 485 Havana_ 20 20 20 20 20 19 76 40 38 Astoria _ 54 54 62 62 62 63 Rushville__ . 10 10 18 18 18 18 56 62 Beardstown 16 16 Alexander 5 Bushnell 19 4 Total_ 100 100 100 100 100 100 100 100 100 Sangamon above Monticello.. Urbana. 590 60 60 48 48 45 Roberts 25 25 25 25 Clinton 10 10 5 5 Bloomington_ 5 5 5 5 5 4 3 7 27 Bement 17 17 Ref No 13 14 15 16 17 18 233 APPENDIX “A.” TABLE NO. A-l—Continued. Flood Periods. Ref. No. Watersheds and rainfall stations. Water¬ shed area, sq.mi. 1926- 27 1921- 22 1915- 16 1913 1904 1900 1898 1893 1892 Per cents of sub-watershed areas. Rantoul_ 50 42 70 72 Monticello_ 40 Strawn_ 14 Lexington_ 7 Philo. 15 15 73 Decatur_ 5 6 Total.__ 100 100 100 100 100 100 100 100 100 19 Sangamon above Riverton_ Roberts_ 2,710 5 5 5 5 Urbana___ 13 13 10 10 10 Clinton.. 10 10 7 7 Decatur... 24 24 21 25 27 21 33 31 Springfield__ 15 15 16 16 9 9 9 27 32 Alexander__ 5 5 5 5 Morrisonville_ 16 16 16 24 15 16 23 21 Pana_ 12 12 12 12 11 32 Bement_ 8 8 Rantoul_ 12 9 15 16 Loami_ 10 10 10 Mt. Pulaski... 5 5 5 Monticello_ 15 Strawn_ 4 Philo_ 3 3 24 Lexington_ 2 Bloomington_ 2 12 Total.... 100 100 100 100 100 100 100 100 100 20 Sangamon below Riverton_ 2,755 Bloomington_ 16 16 16 16 28 25 29 36 42 Clinton.... 16 16 16 16 Decatur... 3 3 3 3 3 2 3 12 Lincoln...... 28 28 28 28 Havana__ 12 12 15 15 15 15 17 21 20 Beardstown... 4 4 Alexander... 6 6 7 7 7 6 8 Springfield..__ 15 15 15 15 14 16 14 29 36 Mt. Pulaski.. 30 30 29 Astoria__ 3 3 Monticello.. 3 East Peoria__ 2 2 Total... 100 100 100 100 100 100 100 100 100 21 South Fork Sangamon above Taylorville_ 570 Decatur.... 10 10 10 30 10 13 31 Pana.... 54 54 54 54 50 100 100 Morrisonville__ 36 36 36 70 36 37 69 Total___ 100 100 100 100 100 100 100 100 100 22 Beardstown to Pearl. 1,620 Rushville. 5 5 16 20 16 16 25 25 Beardstown..... 19 19 19 Alexander... 19 19 24 24 26 19 19 Whitehall..... 8 8 11 11 21 20 Pearl... _ 5 5 'Griggs ville.. 30 30 34 45 40 24 33 47 47 Golden__ 14 14 Coatsburg... 14 13 14 Carrollton. 4 Winchester__ 28 32 Havana... 2 Springfield_ 7 8 Camp Point.. 15 Total... 100 100 100 100 100 100 100 100 100 234 FLOOD CONTROL REPORT TABLE NO. A-l—Concluded. Watersheds and rainfall stations. Water¬ shed area. sq.mi. Flood Periods. 1926- 27 1921- 22 1915- 16 1913 1904 1900 1898 1893 1892 Per cents of s ub-watershed areas. Crooked Creek above Ripley. 1,265 LaHarpe__ 25 25 26 30 25 36 38 Golden_ 22 22 Rushville_ 15 15 17 29 16 28 45 67 Macomb_ ____ 38 38 40 41 Bushnell_ 16 24 34 55 Coatsburg _ ... 7 12 25 Fandon_ 36 Camp Point_ 17 Griggs ville.. 3 Keokuk 30 Havana . ___ 3 Total. _ 100 100 100 100 100 100 100 100 100 Illinois, Pearl to Grafton_ 900 Pearl_ 15 15 White Hall... 38 38 53 53 96 93 Grafton_ 33 33 33 33 43 Alexander_ 14 14 14 14 15 17 15 Carrollton_ 81 75 Loami_ 4 3 Winchester 36 7 Carlinville_ 4 Springfield_ 4 4 Collinsville_ 3 Total__ 100 100 100 100 100 100 100 100 100 Macoupin Creek near Kane . 875 Carlinville_ 75 75 75 75 70 78 67 White Hall. 12 12 12 12 87 68 Grafton_ 8 8 8 8 13 Morrisonville_ 5 5 5 5 5 5 5 Carrollton_ 25 25 Loami_ 4 3 Pana. ... 13 Springfield_ 19 Greenville_ 13 Total. 100 100 100 100 100 100 100 100 100 [JK .. '• 1 - • A#! ’ _.. - 'S 1 .£ oV.S fi*- ' to S3 i ei.o ft.i ,1 '• '• <• ! •4. wSj-tf.i - .f-"-- ’* - - -• 7.P . ■ tt.ft S£. i ylt. ■ ‘t -- . v • ' -- 38.1 S£.l . ' 0 . , i.—»—« -u. . T J — TABLE NO. A-2—WEIGHTED AVERAGE TEN-DAY PRECIPITATIONS ON ILLINOIS RIVER WATERSHED. Ref No. Watershed. Areas. Flood period— August, 1926-June, 1927. Square miles. Per cent. August. September. October. November. December. January. February. March. April. May. June. Total. 4.63 10.76 4.40 3.12 1.42 1.55 2.18 3.34 6.33 5.50 4.32 1 Iroquois at Chebanse. 2,185 8 1.13 1.92 1.68 5.86 1.64 3.26 2.93 0.32 1.15 0.65 1.94 0.53 0.82 0.0 10.60 0.12 1.29 0.14 1.37 0.41 0.40 0.41 2.92 0.01 1.52 3.31 1.50 0.75 2.79 1.96 1.37 1.21 1.74 47.55 3.24 6.22 2.54 2.66 1.49 1.79 1.64 2.70 6.17 4.28 3.42 2 Kankakee above Momence 2,395 9 0.65 2.01 0.58 2.26 1.45 2.51 1.56 0.26 0.72 0.86 1.37 0.43 0.57 0.2 0.70 0.33 1.37 0.09 0.64 0.56 0.44 0.55 1.92 0.23 1.74 2.78 1.65 0.72 1.41 2.15 1.81 0.53 1.08 36.15 3.92 8.55 3.39 2.91 1.42 1.69 2.04 2.96 6.67 4.87 3.83 3 Kankakee above Custer Park.. 5,010 18 1.00 2.26 0.66 3.55 1.64 3.36 2.21 0.27 0.91 0.76 1.69 0.46 0.71 0.1 0.58 0.21 1.36 0.12 1.10 0.50 0.44 0.49 2.36 0.11 1.71 3.42 1.54 0.73 2.05 2.09 1.68 0.85 1.30 42.25 1.70 7.18 2.03 4.40 0.79 1.27 0.91 2.01 5.90 4.68 2.75 4 Desplaines above Joliet — 835 3 0.43 0.94 0.33 1.98 1.74 3.46 1.52 0.36 0.15 1.04 2.97 0.39 0.60 0.1 0.04 0.23 0.95 0.09 0.51 0.29 0.11 0.44 1.24 0.33 1.28 3.61 1.01 1.50 0.99 2.19 1.34 0.47 0.94 33.62 1.59 7.15 1.91 4.47 0.79 1.23 0.95 2.08 6.56 4.87 3.09 5 Desplaines above mouth. 1,430 5 0.53 0.78 0.28 1.69 1.92 3.54 1.38 0.36 0.17 0.98 3.11 0.38 0.55 0.1 0.06 0.19 0.92 0.12 0.57 0.27 0.11 0.53 1.25 0.30 1.33 3.48 1.75 1.33 1.11 2.43 1.65 0.51 0.93 34.69 6 Ill., Morris, to mouth of 3.74 9.33 2.13 4.15 0.99 1.46 2.56 2.42 7.62 4.98 4.05 Desplaines; Kankakee, mouth to Custer Park__ 1,135 4 1.68 1.67 0.39 4.01 1.97 3.35 1.66 0.16 0.31 1.01 2.89 0.25 0.65 0.1 0.20 0.13 1.28 0.05 1.63 0.37 0.56 0.68 0.66 1.08 1.53 3.96 2.13 0.80 1.84 2.34 2.54 0.77 0.74 43.43 3.44 8.39 2.93 3.39 1.24 1.58 1.91 1.74 6.80 4.91 3.75 7 Illinois above Morris_ 7,575 27 1.01 2.00 0.43 3.25 1.63 3.51 1.98 0.26 0.69 0.85 2.13 0.41 0.66 0.1 0.43 0.19 1.28 0.11 1.08 0.43 0.40 0.33 1.33 0.08 1.59 3.38 1.83 0.85 1.85 2.21 1.82 0.79 1.14 40.08 2.28 6.96 2.87 4.05 1.01 1.33 1.36 2.45 5.04 5.09 2.57 8 Fox above Algonquin.... 1,335 5 0.38 1.59 0.31 2.23 1.07 2.66 2.30 0.38 0.19 0.86 2.70 0.49 0.88 0.1 0.01 0.41 0.81 0.11 0.71 0.64 0.01 0.36 1.48 0.61 1.12 2.52 1.40 1.51 0.77 2.81 0.89 0.08 1.6C 34.01 2.46 7.21 2.44 4.65 0.82 1.17 1.32 2.31 5.64 4.88 2.6C 9 Fox above Dayton_ 2,530 8 0.68 1.35 0.43 2.20 1.68 3.33 1.93 0.35 0.16 0.90 3.33 0.42 0.68 0.1 0.02 0.29 0.77 0.11 0.82 0.43 0.07 0.40 1.49 0.42 1.26 2.85 1.53 1.26 0.97 2.65 1.06 0.25 1.29 35.50 4.71 11.42 3.89 4.24 1.30 1.96 2.69 3.07 7.37 6.6C 3.14 10 Vermilion above Streator 1,055 4 2.57 1.78 0.36 5.78 1.32 4.32 3.08 0.26 0.55 1.00 2.97 0.27 0.83 0.0 3 0.41 0.19 1.57 0.20 1.35 0.59 0.75 0.70 2.30 0.07 2.17 3.76 1.44 0.96 3.46 2.18 1.74 1.11 0.29 50.39 4.46 11.45 3.61 4.25 1.26 1.81 2.66 2.95 7.12 6.41 3.26 11 Vermilion above mouth.. 1,280 5 2.46 1.76 0.24 5.57 1.62 4.36 2.86 0.26 0.49 1.00 3.02 0.23 0.82 0.0 0.37 0.18 1.47 0.16 1.38 0.58 0.70 1.67 1.22 0.06 2.11 3.56 1.45 0.99 3.26 2.16 1.89 1.06 0.31 49.24 2.71 11.64 1.63 4.45 0.69 1.04 2.22 2.29 7.02 4.72 4.09 12 Illinois, Morris to LaSalle 570 2 1.49 1.04 0.18 4.06 2.47 5.11 1.27 0.22 0.14 0.93 3.33 0.19 0.63 0.0 3 0.07 0.10 0.89 0.05 1.56 0.26 0.40 0.51 1.61 0.17 1.75 3.15 2.12 0.87 1.82 2.03 2.66 0.69 0.74 42.50 3.32 8.63 2.78 3.74 1.09 1.46 1.89 1.94 6.57 5.04 3.38 13 Illinois above LaSalle.... 11,955 42 1.14 1.69 0.49 3.30 1.65 3.68 1.99 0.26 0.53 0.83 2.54 0.37 0.64 0.1 0.31 0.20 1.16 0.10 1.09 0.45 0.35 0.37 1.44 0.13 1.55 3.27 1.75 0.96 1.80 2.28 1.67 0.65 1.06 39.84 4.74 10.80 2.21 4.67 0.78 1.15 2.39 3.00 6.03 5.62 4.20 14 Illinois, LaSalle to Peoria 1,610 6 1.80 2.13 0.81 5.16 2.36 3.28 1.81 0.20 0.20 0.98 3.51 0.18 0.64 0.0 0.06 0.10 0.98 0.07 1.36 0.38 0.65 0.42 2.30 0.28 1.75 2.78 1.60 1.53 2.19 1.90 2.54 0.84 0.82 45.59 3.49 8.85 2.66 3.80 1.05 1.42 1.94 2.08 6.51 5.12 3.47 15 Illinois above Peoria_ 13,565 48 1.22 1.85 0.42 3.50 1.72 3.63 1.96 0.24 0.46 0.83 2.65 0.32 0.63 0.1 0.28 0.19 1.13 0.10 1.12 0.44 0.38 0.38 1.66 0.14 1.58 3.21 1.72 1.03 1.87 2.22 1.77 0.67 1.03 40.30 5.51 10.83 2.72 3.83 1.13 1.52 2.60 4.39 5.32 8.23 5.03 16 Illinois, Peoria to Havana 1,050 4 1.85 0.91 2.75 7.28 1.52 2.03 2.31 0.15 0.26 0.70 2.69 0.44 0.80 0.0 0.24 0.05 1.30 0.17 1.00 0.63 0.97 0.48 3.35 0.56 1.48 3.38 0.46 1.18 4.59 2.46 2.81 1.76 0.46 51.11 3.96 12.53 4.50 5.23 1.21 1.64 2.38 3.83 6.41 7.41 4.91 17 Valley_ 1,120 4 1.45 1.34 1.17 8.06 1.37 3.10 3.48 0.36 0.66 0.82 4.06 0.35 0.76 0.1 0.34 0.09 1.35 0.20 1.02 0.69 0.77 0.58 2.70 0.55 1.81 3.90 0.70 1.11 4.21 2.09 2.15 1.62 1.14 54.01 4.74 11.09 2.30 4.40 0.96 1.15 2.31 3.14 6.09 7.7C 4.66 18 Spoon above Seville_ 1,580 6 2.25 1.33 1.16 7.19 2.07 1.83 1.77 0.39 0.14 0.83 3.24 0.33 0.71 0.0 0.18 0.04 1.05 0.06 1.19 0.42 0.70 0.34 2.67 0.13 1.84 3.07 1.18 1.88 3.17 2.65 2.16 1.66 0.84 48.54 4.61 11.01 2.37 4.40 0.97 1.19 2.37 3.29 8.06 7.62 4.63 19 Spoon above mouth_ 1,800 6 2.17 1.29 1.15 7.20 1.99 1.82 1.85 0.40 0.12 0.83 3.23 0.34 0.70 0.0 0.20 0.04 1.07 0.08 1.20 0.48 0.69 0.35 2.80 0.14 1.83 3.15 1.08 1.82 3.13 2.67 2.11 1.68 0.84 48.52 3.69 9.41 2.75 3.94 1.07 1.41 2.04 2.57 6.38 5.59 3.75 20 Illinois above Havana 17,535 62 1.34 1.73 0.62 4.37 1.71 3.33 2.07 0.26 0.42 0.82 2.81 0.31 0.67 0. It 0.26 0.14 1.16 0.11 1.11 0.44 0.49 0.46 1.81 0.30 1.63 3.21 1.54 1.10 2.24 2.25 1.89 0.93 0.93 42.60 4.46 9.46 2.82 4.86 1.10 1.54 3.07 5.28 6.21 6.40 4.02 21 Beards town.... 485 2 1.20 1.74 1.62 5.86 1.68 1.92 2.35 0.13 0.34 0.93 3.28 0.65 0.69 0.0 10.39 0.00 1.43 0.11 1.44 1.03 0.60 0.61 4.54 0.13 2.52 3.60 0.09 1.56 1.93 2.91 1.43 2.59 0.00 49.22 4.94 13.13 5.32 3.55 1.01 1.94 1.02 4.75 6.87 6.00 4.30 22 ton.. 2,710 10 1.29 1.99 1.66 8.60 0.82 3.71 4.31 0.33 0.68 0.61 2.50 0.44 0.29 0.1 10.60 0.07 1.44 0.43 0.33 0.37 0.32 0.57 3.78 0.40 3.22 3.47 0.18 1.32 1.53 3.15 0.97 2.30 1.03 52.83 4.42 13.14 5.35 4.25 1.04 1.74 1.26 4.65 6.77 6.22 4.15 23 Sangamon above mouth 5,465 19 1.06 1.74 1.62 8.62 0.97 3.65 4.37 0.39 0.59 0.64 3.16 0.45 0.47 0.K 10.47 0.06 1.31 0.37 0.52 0.41 0.33 0.76 3.50 0.39 2.80 3.79 0.18 1.33 1.86 3.03 1.10 2.18 0.87 52.99 3.89 10.27 3.35 3.97 1.07 1.49 1.85 3.07 6.45 5.74 3.84 24 Illinois above Beardstown 23,485 83 1.30 1.74 0.85 5.38 1.53 3.36 2.61 0.28 0.46 0.76 2.88 0.33 0.61 O.P 0.32 0.11 1.22 0.16 0.97 0.43 0.45 0.52 2.24 0.31 1.89 3.33 1.23 1.16 2.13 2.45 1.70 1.26 0.88 44.99 25 4.73 14.10 4.55 4.06 1.32 1.54 1.21 6.47 6.20 5.62 3.85 Pearl. 1,620 6 0.68 2.41 1.64 8.84 2.30 2.96 3.94 0.29 0.32 0.83 2.46 0.77 0.86 0.0( 10.46 0.00 1.19 0.35 0.47 0.42 0.32 0.85 5.21 0.41 2.46 3.50 0.24 2.11 0.98 2.53 1.22 2.37 0.26 53.65 26 4.12 10.22 2.78 3.63 1.14 1.38 1.65 4.72 5.25 5.55 4.44 Ripley.. 1,265 4 1.10 1.81 1.21 6.66 1.67 1.89 2.09 0.49 0.20 0.81 2.40 0.42 0.87 o.oc 0.27 0.01 1.18 0.19 0.66 0.48 0.41 0.63 3.73 0.46 1.53 3.02 0.70 1.57 2.01 1.97 1.79 2.65 0.00 44.78 3.91 10.39 3.39 3.92 1.06 1.49 1.80 3.36 6.39 5.73 3.85 27 Illinois above Pearl_ 26,370 63 1.24 1.77 0.90 5.62 1.65 3.22 2.65 0.30 0.44 0.75 2.80 0.37 0.62 0.13 0.31 0.10 1.22 0.17 0.92 0.43 0.45 0.55 2.48 0.33 1.89 3.34 1.16 1.23 2.04 2.46 1.68 1.30 0.87 45.29 5.34 12.98 5.22 3.72 1.35 1.43 0.67 5.64 8.08 6.38 3.63 28 Illinois, Pearl to Grafton. 900 4 0.26 2.65 2.43 7.34 1.41 4.23 4.15 0.51 0.56 0.67 2.34 0.71 0.64 0.04 0.67 0.00 0.97 0.46 0.26 0.25 0.16 0.98 4.23 0.43 3.29 4.71 0.08 2.90 0.67 2.81 0.54 2.45 0.64 54.44 4.30 12.21 4.82 4.08 1.61 1.68 0.81 5.19 8.67 8.72 3.82 29 Macoupin Creek.. 875 3 0.22 2.51 1.57 5.59 2.05 4.51 3.14 0.57 1.11 0.64 2.82 0.62 0.49 0.14 0.98 0.02 0.99 0.67 0.24 0.38 0.19 1.01 5.66 0.52 4.91 3.75 0.01 3.44 ). 97 4.31 0.44 2.91 0.47 55.91 3.97 10.51 3.48 3.94 1.08 1.50 1.74 3.48 5.51 5.86 3.83 zo Illinois above Grafton_ 28,145 100 1.17 1.83 0.97 5.66 1.56 3.29 2.61 0.27 0.60 0.76 2.78 0.40 0.61 0.13 0.34 0.10 1.21 0.19 0.87 0.42 0.45 0.54 5.61 9.33 2.00 3.40 1.11 .34 .99 2.53 1.70 .13 1.00 45.90 ' • ■ : . :ir>0- *)>' i*q b>■< .IbJoT .liiqA .v uWt 1.0 01.8 i 8.1 &.S k fi-o.o ''.I 3* It ae.o IS. 8 80.0 ■ ■> '£.0 Gfr.fr .1 16 Q.lt ;«.o aO.l f.1 • t 04.* U. 0 fc&j ».l J .e ;Td*'0 10.0 O&iO jkr,0 1 r . « - !;«fr.i a?.i iO'.'.t ,v-.S 'Ll • • gfr.vr «>.0 8't.O 00.0 81/ kl 87.0 cO.O 81.1 ?s.s fi .0 i8.e isj. 88. S 8T.0 ,8.0 1 *$i&i *0.1 88. r 1.0 frl.0 U.O 08.0 %/> l.« frg.l s&.o ;. f • 2.1 »v.o at.! Jft.l 8T.G 81.0 tt.O M.itl ; 1.0 oo.s tt.t «•. i ofr 0 *;a.o 81.0 V&.0 fr«,t It .at i6.r 08.1 :s.O dt.i CS.C 8*1 fr.I 08.1 Pfr.C 03.0 se.o F ti.i M.l J 0.1 10.1 jfrC.O i&.S 80.fr it.: WM x.i n i Sf.t oi'.i 03.fr /Ottl ■i.o T8.I 51. t 03 f ..JO TABLE NO. A-3—WEIGHTED AVERAGE TEN-DAY PRECIPITATIONS ON ILLINOIS RIVER WATERSHED. Ref. No. Watershed. Areas. Flood period—October 1921-April 1922. Square miles. Per cent. October. November. December. January. February. March. April. Total. 2.77 4.27 1.70 1.69 0.98 5.95 4.94 1 Iroquois at Chebanse.— 2,185 8 1.20 0.32 1.25 0.28 3.68 0.41 0.39 1.11 0.20 0.73 0.68 0.28 0.21 0.23 0.54 0.34 2.85 2.76 1.38 3.10 0.46 22.30 3.92 3.73 2.44 1.86 0.88 4.58 4.02 2 Kankakee above Momence... 2,395 9 1.43 1.17 1.32 0.47 2.70 0.66 0.81 1.54 0.09 0.98 0.70 0.18 0.28 0.23 0.37 1.14 0.98 2.46 0.73 2.91 0.38 21.43 3.30 3.95 2.07 1.75 0.93 5.26 4.40 8 Kankakee above Custer Park-- 5,010 18 1.29 0.84 1.27 0.37 3.08 0.50 0.61 1.32 0.14 0.86 0.80 0.09 0.28 0.23 0.42 1.08 1.56 2.62 0.98 3.05 0.37 21.66 3.67 3.37 3.31 1.18 1.20 4.59 3.36 4 Des Plaines above Joliet... 835 3 1.01 1.31 1.35 1.45 1.63 0.29 1.25 1.94 0.12 1.02 0.12 0.04 0.30 0.05 0.85 0.67 1.07 2.85 1.43 1.76 0.17 20.68 3.37 3.24 3.36 1.29 0.96 4.69 3.30 5 Des Plaines above mouth.. 1,430 6 0.87 1.23 1.27 1.26 1.76 0.22 1.33 1.92 0.11 1.09 0.20 0.00 0.28 0.05 0.63 0.73 1.10 2.86 2.61 0.46 0.23 20.21 2.57 3.45 2.70 1.40 0.88 5.02 3.94 6 Ill . Morris to mouth of Des Plaines; Kan- kakee, mouth to Custer Park. 1,135 4 0.72 0.76 1.09 0.50 2.81 0.14 1.19 1.42 0.09 1.01 0.24 0.15 0.24 0.24 0.40 0.66 1.56 2.80 1.73 1.65 0.56 19.96 3.21 3.74 2.40 1.60 0.93 5.10 4.12 7 Illinois above Morris. 7,575 27 1.12 0.86 1.23 0.51 2.86 0.37 0.83 1.44 0.13 0.93 0.62 0.05 0.27 0.21 0.45 0.93 1.49 2.68 1.17 2.56 0.39 21.10 4.46 2.19 3.18 0.87 1.73 2.52 2.48 8 Fox above Algonquin. 1,335 5 1.55 1.58 1.33 0.99 1.04 0.16 1.34 1.75 0.09 0.79 0.08 0.00 0.28 0.06 1.39 0.12 0.62 1.78 0.63 1.76 0.09 17.43 3.75 2.46 3.31 1.07 1.25 3.16 2.38 9 Fox above Wedron___ 2,530 8 1.08 1.41 1.26 0.94 1.38 0.14 1.47 1.76 0.08 0.96 0.09 0.02 0.28 0.05 0.92 0.45 0.70 2.01 0.76 1.46 0.16 17.38 2.80 3.27 1.63 1.66 1.27 5.69 4.14 10 Vermilion above Streator... 1,055 4 1.22 0.56 1.02 0.43 2.68 0.16 0.61 0.97 0.05 0.92 0.52 0.22 0.26 0.41 0.60 0.87 2.28 2.44 1.18 2.22 0.74 20.36 2.79 3.17 1.84 1.59 1.21 5.31 3.97 11 Vermilion above mouth.. 1,280 5 1.11 0.62 1.06 0.45 2.57 0.16 0.79 1.03 0.02 0.91 0.46 0.22 0.25 0.38 0.58 0.76 2.18 2.38 1.25 2.02 0.70 19.88 2.54 2.76 3.00 1.19 0.82 3.59 2.84 12 Illinois, Morris to LaSalle... 670 2 0.44 1.00 1.10 0.64 2.00 0.12 1.71 1.27 0.02 0.98 0.10 0.11 0.20 0.14 0.48 0.48 0.91 2.20 1.33 1.04 0.47 16.74 3.21 3.30 2.52 1.46 0.99 4.60 3.63 13 Illinois above LaSalle... 11,955 42 1.07 0.94 1.20 0.68 2.45 0.27 1.01 1.43 0.08 0.93 0.36 0.17 0.27 0.19 0.53 0.79 1.34 2.47 1.08 2.18 0.37 19.71 3.01 2.32 2.77 1.20 0.95 4.15 2.66 14 Illinois, LaSalle to Peoria_ 1,610 6 0.48 1.01 1.52 0.46 1.79 0.07 1.73 1.00 0.04 0.99 0.14 0.07 0.22 0.19 0.54 0.79 1.04 2.32 1.36 0.77 0.53 17.08 3.18 3.18 2.55 1.42 0.98 4.54 3.51 15 Illinois above Peoria. 13,565 48 1.01 0.94 1.23 0.56 2.37 0.25 1.10 1.37 0.08 0.94 0.44 0.04 0.27 0.19 0.52 0.80 1.31 2.43 1.11 2.00 0.40 19.36 2.83 2.81 2.59 1.63 1.84 5.12 3.59 16 Illinois, Peoria to Havana. 1,050 4 0.74 0.75 1.34 0.50 2.15 0.16 1.67 0.79 0.13 1.43 0.05 0.15 0.35 0.57 0.92 0.69 1.80 2.63 1.36 1.51 0.72 20.41 2.84 3.41 2.34 1.48 1.48 5.65 4.16 17 Mackinaw above Green Valley..... 1,120 4 0.92 0.62 1.30 0.51 2.71 0.19 1.07 1.11 0.16 1.16 0.22 0.10 0.32 0.33 0.83 0.60 2.40 2.76 1.60 1.67 0.89 21.36 2.58 1.74 2.20 1.64 1.55 3.87 3.11 18 Spoon above Seville. 1,580 6 0.44 0.86 1.28 0.26 1.33 0.15 1.22 0.90 0.08 1.40 0.14 0.10 0.30 0.24 1.01 0.76 1.08 2.03 1.44 1.17 0.60 16.69 2.59 1.76 2.19 1.62 1.57 4.06 3.21 19 Spoon above mouth... 1,800 6 0.60 0.85 1.24 0.27 1.34 0.15 1.24 0.86 0.09 1.38 0.14 0.10 0.30 0.24 1.03 0.75 1.19 2.12 1.47 1.22 0.52 17.00 3.03 3.01 2.47 1.44 1.09 4.56 3.49 20 Illinois above Havana. 17,635 62 0.91 0.87 1.25 0.53 2.28 0.20 1.15 1.23 0.09 1.02 0.37 0.05 0.28 0.21 0.60 0.62 1.50 2.44 1.16 1.87 0.46 19.09 2.40 1.73 2.15 1.63 1.75 6.21 4.25 21 Illinois, Havana to Beardstown. 485 2 0.80 0.91 0.69 0.27 1.31 0.15 1.32 0.68 0.15 1.40 0.09 0.14 0.43 0.12 |,20 0.63 2.84 2.84 1.68 1.93 0.64 20.12 2.12 4.29 2.42 1.47 1.00 8.28 7.07 22 Sangamon above Riverton. 2,710 10 0.93 0.31 0.88 0.36 3.77 0.16 0.52 0.72 1.18 0.94 0.36 0.17 0.41 0.04 0.55 0.74 4.67 2.87 2.59 3.93 0.55 26.65 2.20 3.83 2.40 1.51 1.15 7.39 6.18 23 Sangamon above mouth___ 5,465 19 0.87 0.42 0.91 0.47 3.22 0.14 0.68 0.90 0.82 1.04 0.29 0.18 0.40 0.04 0.71 0.65 3.90 2.84 2.42 3.08 0.68 24.66 2.83 3.14 2.44 1.46 1.12 5.24 4.10 24 Illinois above Beardstown_... 23,485 83 0.91 0.77 1.15 0.51 2.46 0.17 1.05 1.14 0.25 1.03 0.36 0.07 0.31 0.17 0.64 0.63 2.09 2.52 1.46 2.11 0.53 20.33 2.37 2.12 2.20 1.54 1.19 6.63 6.14 25 Illinois, Beardstown to Pearl_ 1,620 6 0.67 0.56 1.14 0.38 1.64 0.10 1.06 0.63 0.51 1.14 0.21 0.19 0.47 0.01 0.71 0.63 2.61 2.39 2.87 2.62 0.65 21.19 3.01 1.54 1.73 1.14 1.76 4.69 4.24 26 Crooked Creek above Ripley_... 1,265 4 1.02 0.91 1.08 0.23 1.13 0.18 1.07 0.50 0.16 0.96 0.09 0.09 0.41 0.19 1.16 0.80 1.33 2.56 2.47 1.27 0.50 18.11 2.76 2.96 2.37 1.44 1.14 5.18 4.16 27 Illinois above Pearl_ 26,370 93 0.85 0.77 1.14 0.48 2.32 0.16 1.04 1.08 0.25 1.03 0.33 0.07 0.31 0.16 0.67 0.62 2.07 2.49 1.55 2.11 0.49 20.01 2.05 2.60 3.00 1.70 0.82 6.83 8.18 28 Illinois, Pearl to Grafton. 900 4 0.64 0.22 1.19 0.58 1.84 0.18 1.18 0.57 1.25 1.22 0.18 0.30 0.41 0.00 0.41 0.74 3.31 2.78 3.99 3.44 0.75 25.18 1.46 4.07 2.79 1.32 1.01 8.28 9.47 29 Macoupin above Kane___ 875 3 0.74 0.08 0.64 0.38 3.65 0.04 0.92 0.42 1.45 0.83 0.15 0.34 0.49 0.01 0.51 0.87 5.16 2.25 5.36 3.44 0.67 28.40 2.70 2.99 2.39 1.44 1.12 5.31 4.42 30 Illinois above Grafton. 28,145 100 0.84 0.74 1.12 0.48 2.35 0.16 1.05 1.04 0.30 1.03 0.32 0.09 0.31 0.15 0.66 0.64 2.21 2.48 1.72 2.19 0.51 20.37 * TABLE NO. A-4—WEIGHTED AVERAGE TEN-DAY PRECIPITATIONS ON ILLINOIS RIVER WATERSHED. 236 FLOOD CONTROL REPORT. O H CO o CO CO CO N CO ao p^ CM o p^ o 40 T-H TF TF 05 • 40 CO CO 40 CO CO CO 40 40 P^ o cm , O o o CM CM o t 05 CM T-H 05 CM oo o oo 1 ""' 40 CM *-< 05 ^F OO CO TF CM TF CM CO CO o CO 40 CM ° d o O O © o O d o © d © © ^H o T " H o d O >> Pi CM CM p- 05 CO r^- CO ^F 05 CO G o t-h o o o o o ^H o o G • • • • • • • • p o o o o o o o o o d X> CD o 05 CO 05 p- CM 05 oo iO CO ^H t—I T-H CO CO T-H T-H p^ 40 T-H • • • • o o o o o o o o o o »o CM CM 05 CO CM o 05 oo CO CO __ CM o oo 40 CO o p^ ^F CO P^ CO CO CO 05 oo CO CO 05 CO T-H t^T 40 O p^ CO T-H •* t-H CO 05 TF CM 00 05 p^ oo 40 CO ^F CO CO CO ^F CO oo G O o o o o o O o o o o o o CM 05 o T-H T—1 ^F OO o t-H T-H O t-H o o o o o o o o o o o o o o o o o >» P G G Pi G £ -p» G o cd G CD • M o G a 1 o i i CD Pi i i O ' o o G i i i i Q ; c © a Pi o -p> CD i -p> .£ J3 G O 4—t 1 ° ! js ; o 3 o G HJ 1 £ o > > > o o S P o O £> c3 © -*-5 Ph G G GQ CD 0) (D w Q Q PH .2 ’p p O £ © > o x> © o a 3 cr a o M © > O .D © X O £ o ■4-1 © © hi G O CO P o T3 > (D o .o © © > o c o X! © a X p o 0> (h > APPENDIX “A.” CO CO CM CO CO ■*« r- r^. CM o o CM 05 CO T—H CM T-H 40 oo TV oo CO CO CO CO 05 CO CO 05 © T-H 05 CO CO CM co CO CO oo CM CM t-H 05 o CM 05 40 CO CO 05 CO 40 CM 40 Tt< CO CM 40 CO CO CM o 40 T-H CO T-H T-H 40 CM 40 o o o O o o o O o o o o o o o o o o o o o O o o T-H o CM OO CM oo CO 40 CM CO CO oo o o o o o o o O o o o o T-H o o o o o o o o o o o o »o T-H OO 05 05 CO 40 oo CM 05 f-H CM t-H CM CO CM CM CM CM © o © © © © © © © © © o Tf« oo CO 05 CO CM t-H 40 40 CO T-H to CO CO CO CO iH CO CO o CO oo 05 05 Tt< O 40 T-H 40 ^H o o oo 40 T-H CM 05 CO CM CM oo CO CM CM CM 40 CO CM CM CO T-H 40 CO co CM T-H CM CO CM CM 05 T-H 05 CO 05 CO CO CM T-H o 40 o CM CO OO 40 CM T-H t-H T-H T-H CO CO T-H CM CM CM © 40 40 CM CO _ CO 40 CM 05 40 CO CM oo 05 05 05 40 CM o t-H 05 CO QO iH o o o o T-H T-H T-H T-H o T-H CM CO CM T-H t'- T-H *** 05 CO 05 CO OO CM CO 05 CO CM CM T-H o CM CO 40 o CO CM 40 OO CM r-H 40 40 05 CM o CO CM 40 T-H T-H CM CO o T-H o »H o o O ^H o T-H o T-H O o O T-H o tH o CM T-H CO T-H CM 40 o CO 05 t-H 05 05 o CO 05 OO OO 40 CO Tt< 40 05 05 CO CO o © o o o o o o o o o o CM O 05 O O © © 05 oo o o © © © © CO o 40 »o CM CM © © © © o CO oo CO CO CM CM CO o © 40 o 40 o o o o 40 40 oo 40 T-H co 40 CM oo o CO oo CM 40 05 CO 40 o ^H 40 oo 40 T-H ^H ^H CO ^H T-H T-H T-H t'T. 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A-5—WEIGHTED AVERAGE TEN-DAY PRECIPITATIONS ON ILLINOIS RIVER WATERSHED. TABLE NO. A-5—Concluded. 240 FLOOD CONTROL REPORT. CO T—H C5 ft £ cZ 3 G cZ "d .2 *2 CD ft 'd o o i ' < Ph 03 d © u. «< CO CO OO o G CM G T-H CO T-H 05 o t-h o r- OO CM CM o cZ , Ph cZ ■**< OO CO ^H T-H CO d o o o o o T—H o o o o ja o o o o o o o o o o “5 CO G 00 CO CM CM OO G G CO G 05 G o oo G G 05 o o o o T—H o O O O O G (M CM o oo TJH Tt« G G CM 1-4 +* © d \ G CL © ^ CD © . o o G o G O o O O G oo G T-H G G CM OO o CO C3 CD CM G © G G O T-H G oo G —' rd T-H T—H T-H CO T-H T-H T-H T-H r— O' C T-H T-H T—H CO G *d CD w P-. CD -4-3 I I I 1 1 i i 1 1 1 1 1 1 1 1 1 >> i • l l I i 1 1 1 1 © 1 1 1 1 T—< 1 1 1 • CD 1 1 1 1 _08 1 1 • 1 a3 a c3 > i i i i i i X3 1 U4 1 cj d i i i H-> d o a a> > o C3 m c3 >1 o H-* CD c Ih o 1 o > o o O > cZ w O .2 tZ o © © © pH a © > o tG i i -2 • H > i i ,G -4-3 G O a © > 03 a as > aS K a) > O d o s 00 x> c3 oo cc -O c3 CD Ph CD a! C ^3 S3 tG c3 03 00 "5 o ” O o o ^3 O G c C c a © o o C CD c3 a a > *-H H >-H h-H S m CO HH APPENDIX “A.” 241 CO 00 r- 05 00 CM CM 05 CM -cf 40 oo CO CO 05 ^H 40 T-H CM 05 T-H 40 Tf T-H ^H t*H T*H ^H T-H T-H o CM t-H oo CO CM oo •«v CO CM T-H »o 40 CO CO 40 Ttl O Tt« CO 40 05 CO CM r—< o O 05 CO CM CM CM CO 05 CO CO O CO © CO © CM © CO o CO © CM © CO © CO © CM o 05 05 T-H 05 05 T-H o rH o o o o T-H o o o © © o © © © © o o 05 *rt< CM 40 o 05 40 o o CM 40 40 o o 40 oo oo CO CO CM CM CM CO CO CM CM CM CM CM CO CM oo CM O CO Tfi !>. •**< r- t-H CO oo T-H CM CM 05 O CM CO oo CM 40 oo CO CM 40 oo T-H o CM 40 CO CM CO 40 40 40 CO Tt« CO CM CO 40 40 CO 40 CO t-H OO CO 40 CM O CM CM o N CO 40 CO 40 40 O •o © © © © o © o o CO CO cm 40 t'T. T-H CO 40 CO CM CM CM CM CM CM CM CO CM © o © © © © © O o o oo CM T-H 40 oo CO o CM T-H OO CM CO 05 05 40 r- T-H 40 CM CM oo CM 00 »o OO Tf« CM 40 40 o T-H oo 40 CM CM tH © o t-H tH T-H T-H CM CM ^H T-H T-H T-H T-H o T-H ^H CM o CO o O 40 CO T-H 40 o o o o o o o o o o o © © © © © © © o o 05 oo t>. o oo CO t-H T-H CO T-H CM CO CO CM CO CM CM CO CM © © © © © © © © o o I>- o »o oo CM CM T-H 40 oo CO 40 CM o 40 CO o CO CO »o CO CM 05 o o CO r^T oo 05 or !>► ^H © CM CO t-H CM © CM © t-H © CM © o o CM o 05 05C©*«ct<05T-H050t s -CO COCMOOOt-»t-h05CMOOO Ot-Ht-Ht-Ht-HOOCOt-Ht-H »OC0Ot^00OC005O40 COOt— ia5t>-i005CO 40 05 Ot-Ht-hOOOOOt-hO CMOC^COCO-^CO^COO T-H t-H OO 05 O 40 o 40 40 o 40 o o 40 40 oo T-H co oo CM CO o CO CM CO 05 CO T-H CM 40 CO t-H T-H co . oo CM CM CM a it o i i H-> i GO T3 a o i i 1-4 c3 (1) fa a> rCj « > o O H-> a as © > © > o o s> as as e3 X a o a o a a • rH 03 03 to M a a • -J as 03 4-H co CO T-H CM co CM CM CM 6 a & o -*_» GO 13 rt 3 ffl o J2 c3 oo O d H oS a> P-. a C£ o -n> oo ■a l-C cj a> « o a «5 IM a s © > o £> as M 0) Cj o T3 © dd o O i-. O to CS o3 © CM o -Q a3 w 3 N Cl » © i c c3 H M o © > d c> o o u o x> as U-i cS o H-5> © 4h O T3 i © M O a> > o Ph a • rH rO jn a 3 (C o o O d o d 03 • rH 4-H IS h-H oo 05 o CM CM CO 16 F C TABLE NO. A-6—WEIGHTED AVERAGE TEN-DAY PRECIPITATIONS ON ILLINOIS RIVER WATERSHED. 242 FLOOD CONTROL REPORT. CO CO 05 *—( 05 05 ^4 05 to tO CO 05 CO CO 1—4 05 o 1—4 05 CO 05 o CO o ^4 y-^ y—* 1-4 i—4 i—4 1-4 H to CO 05 o o CO CO Tt« 05 05 oo to ■Tt< CO 4J4 1-4 tO 05 oo 05 CO ^—4 00 CO ® 05 CO CO ▼-4 o 05 oo to o CO 05 CO CO 05 05 cc CO 05 CO 05 05 1—4 05 ^4 CO 05 CO 05 o 05 CO 05 to oo CO fc- 1—4 05 05 1—4 05 05 1-4 o ft • • • • • • • • ■ c o O o o o o O o o O CO 05 05 05 05 05 o CO O i—4 iO CO 05 05 05 oo 05 to ^4 vH o o 1—4 i-* o o tH 05 oo lO 05 co 00 ■^f to 05 oo 1^- CO CO CO CO 05 CO to oo 05 C 1 « o CO o 05 o O 1-4 05 o Tt« no tO CO no CO IO to 05 05 to CO to o to to CO o 05 no lO CO to T—4 05 i-4 ^4 Tt< 05 o 1—4 CO 05 05 • • • • • • • • • • 1—4 1—4 1—4 05 05 1—< CO 05 s 05 iO o OO o CO oc OO HO iO iO CO oo oo 05 oo CO o o o o o o o o o o bO oo CO 05 no o 05 CO o CO 05 Tf< 1—4 CO 4*4 CO 05 to Ol CO iO 05 CO 05 to o CO i—4 o 05 o CO 05 to 05 . 05 05 ^—4 o t—4 1—4 05 ^4 T—4 o 1-H o 1—4 >1 b. ci T—4 05 1—4 o o 05 to 1-4 3 to Tt< Ttl to 05 CO 1-4 32 o o o o o o o O o o 0 Ph CO o CO to CO CO O 05 05 (M 1—H ^4 CO o 05 o o o o o o o o o O to CO CO oo CO CO CO , 00 CO CO CO 1-4 o to 05 05 CO CO CO 05 CO to oo o 05 CO to rt* 05 . CO t-4 CO T—4 CO ^■H 1—H o 1—4 o 05 o 05 ^4 o O 1—4 o CO 1—4 ^5 o3 4t< 05 CO CO 1-4 oo oo •^f CO 4f 05 o o 05 to 4^4 OO 33 a i-4 f—i 1—4 1-4 t—4 o o 1—4 c3 >“5 OO 05 oo CO CO 05 o i-4 rH i—4 05 05 05 05 o i-4 o o o o o o o o o o 00 05 oo CO to T}< to oo to F-. O G 05 CL o ^ o O o a I o 05 >> t-. 2 £ a .2 a> o* O co c3 O f- < p . to to o to o to to to o to OO 05 i—4 CO CO CO CO CO to o3 O l4 CO o 00 1—4 to CO to o 3:3 s m c 05 05 to 1—4 t-4 r>- ^4 05 t4 • i 1 1 1 j ; i 1 i 1 T3 0) -C co Fh o c3 £ o X c3 ® 0> c3 a 03 34 b. a3 Ph b* « tn 3 o o > o 32 c3 O a> X c3 3 4 a o3 O •-5 ® > o X c3 as o c • H G s ® o Q 3 o a o > o •O c3 gg o c Pm GQ 0 Q 3 o a of 0 c3 £ W ® O a £ s GG o Q o JG -+-> o s* StS .2 (3 C 3 SO - o b. o a> > o XI c3 tn ‘3 3 cr c o M o 32 03 >4 O fct a o b- T3 ® £ o > o -Q aj X o l. o - 4-5 cl 0 t-H -4-5 03 0 > o pO c3 G o u o > APPENDIX “A.” ^H © © © © ■*r ^H © T-H © © © © © CO © © CO CM © CO T-H CM © CM CM © © CM © t-H T-H T-H T-H T-H T-H ^H ^H T-H © CO CM OO OO t>- © © Tfl © © © © © t'T. © CM © 00 T-H T-H 00 © © © t-H © © © © © © CM © © oo © CO © CO 00 CO ^H CO CM CO CM CO CM CO CM CO CM CO T-H CM T-H CM T-H CO CM Tt« CO •*f CM © CM © © © © CM T-H © © CM © CO CM © T-H © ^H © © T—H © T-H © © © © © © © © © © © © CM _ © T-H T-H © T-H CO © T-H © CM CM © y—4 © CM oo T-H ***» © v—i T-H tH © T-H -< © © T-H rH ^H CM CO © © t^. CM T-H T-H OO © oo © T-H T-< © CO oo CM © © CO Tfl CO CM © OO !>. CO © CO co © © 00 © © © co CM © CM CO CM CM CM CO co CM CO CM CM CM © © CM t-H CO © OO T-H © OO CO *** CM © ^H co © © Tfl CO T-H th T-H ^H ^H tH T-H ^H T-H ^H T-H T-H oo cm CM © © © © oo CO ^H © © © CM © CO CM © © © CM © © © © © © © © © © © © © CM © CM © CM © © © T-H © © © CM OO CM © © Tt< OO © t-H © © OO T-H CM OO T-H CO CO © CM © CO © © © OO CO iH t-H ^H ^H T-H © rH T-H T-H © T-H © © © © © T-H © T-H © ^H © CO © co CM © CM © CO © oo , " H CO 00 T-H T-H T-H © © © © © © © © © © © © © © © © T-H T-H oo CO CM , © T-H © CM T-H CM © , “ H T-H r - H © CO © © © © © © © © © © © © tH © oo © CM CO © oo © Tf< CM T-H CM © © CM T-H CM © © © © © oc CM © © T-H 00 © © © © © © CO © ° CM © CM © CM © CM T-H CM T-H CM © CM © CM © CO ^H CM T-H © © CO © t>. CO © CD CM © © Tf CM Tt< oo © © © © 00 CM t-H T-H T-H T-H © T-H CM CM T-H T-H © OO © © © © © T-H CO © CO t-H CM T-H CM CM T-H T-H CM © CM © © © © © © © © © © © © ©CMCM©OOt*«’*Ji©©CMCM© ^ ©T-H © © © © © © © © © © © © 00 N © T-H © © CM oo © CO 00 T-H CM © © © © © T-H © OO © ^H T-H T-H CO T-H T-H ^H tH t>T CM 243 TABLE A-6—Concluded. 244 FLOOD CONTROL REPORT. 05 t-H T-H CM C5 ^F O 00 05 CO CO o T-H 00 CO tF CM ic CO CO ic 00 CO o ^H T-H T-H T-H T—H T—• T-H T-H pH TF t-H CO T-H oo CO 00 CO H , T-H 1C -TF iC OO CO CM 05 CO CO ic oo 05 OO CO 05 O CO TF CM CO CM ic tF TF CO CO CM 0 TF 1C ■rF CM ^H CM TF OO CO CO *tF CO CO s- CO T-H CM o T-H 1C TF T-H a • • • • • < o o O © o 0 O 0 ic CM o CM 00 ic TF* o o T-H CM t-H CO o CM T-H ic T-H CM T-H CM T-H TF CO CO CO oo O CM CO 'TF CO 05 CO !>. CO in' o CO o T-H 05 tF tF T-H o T-H ic TF OO *-• T-H CO a co TF ic CO tF CO tF CO 1C CO 1C TF CO ic CO *< i 05 05 o oo 05 00 T-H 05 Ih o3 CO CO T-H CO CM TF T-H hH T-H T-H T-H 0 T-H T-H £ CM t-H oo 05 05 ic CO »c 1C CM ^H TF CM tF TF C o o © © o O 0 0 a ►”5 1 TF 1C T-H oo 05 o CO CO CO CO 00 0 T-H T-H CO ic ic oo CM ^F oo tF TF oo TF CM 00 1C ^F 00 *t3 o 1—1 o T-H o T-H o o o T-H o 0 0 0 O T-H 0 >. <3 Ch t* c3 oo CO oo CO CO 1C tF TF iC tF CO CM ^F T-H CO TF Hd o *h o © o © o 0 0 0 Q 0> B B ^H T-H CO !>. •tF TF CO CM t—h CM T-H T-H 0 0 T-H o © © © o 0 0 0 T-H oo TF p- tF T-H oo "TF 00 CM 05 1C oo iC CO o o o o CM 1C TF CO I>- 0 . CM CM T-H CO © CO hH CM T-H CM T-H CM 1 —H CM T-H >> s- a O 1C CM T-H CO CO o CO y—t ^F CM CO G T-H ^H t-H CM T-H O 0 T-H c3 ►c CO 05 CO T-H CM CO 0 CM CO CM 1C ic CO CO CO CO o o o o o 0 0 0 05 CO CO TF CO TF CO 0 T-H oo 05 0 © G *“< B o ^ o GQ > © a £ © 1 1 4 1 1 1 1 1 1 1 1 P O — CD P c3 « CD > 1 l l l l l P o a "0 u c3 a is > o X1 1 T-< Sh c3 c3 u 0 0 -O c3 O «*H a o > o Si c3 P O rl o £> a o -4-5 ® nd u a o B C$ c CD H o O 0O c3 0 — « « Jh cj 0 Xi ci P CQ CQ CD CQ CQ CQ c3 M G o o A! "o • *H O 0 "o _G _G o _G a 0 cj a cj m • k-H o <—• M £ 4-H coTFiccot>-ooo50 TABLE NO. A-7—WEIGHTED AVERAGE TEN-DAY PRECIPITATIONS ON ILLINOIS RIVER WATERSHED. APPENDIX “A.” 245 05 o 05 CO CO CM TP o > c3 CM lO o o on 05 ^P OO 3 40 Tp CM CM CO 'TP r-H CO CM • • • • • • • • • • .a o o o o o o o o o o 03 Eh TP TP o CM 05 05 05 TP 05 Tp CO TP o 40 OO 05 r-H r-H ^H r-H CM rH iH ^H rH 05 o CO o CO 05 o CO o 05 o Tt< TP o CM o TP o 40 o CO hH CO o 40 o 40 o CO o 05 o 40 o CO o r-H o . d d d © © © r-H o r-H o ^H o o d r-H d d r-H d c3 3 05 CM l>r o oo r-H tP CO »o CO CO CO r-H CO TP 05 3 d d d ^H r-H r-H d rH ^H o d ►o o CO Tp 40 05 05 CM CO OO T“H o CM CM r-H r-H CM CM r-H CM d © © o o O d d d d t-. -fi CO 05 oo CO 40 40 oo 40 A c Ph GO 3 o o d A 3 •20 1 73 a l l OJ £ a 3 X3 a 03 o 03 ►■o 03 > G C3 > D O (h tH o 3 O' a c o 4-5 m 03 03 > > o o -3 a o > rft o o r& X! D <13 > O yO d 73 b£> 03 o O -*■5 cO yO c2 03 03 pQ a 03 03 a cn 03 c c3 CD 03 a -a .2 a u < o > £ 03 > X3 Oj C O oj d 13 o s2 i O O rO 3 Ph Ph o d d g C c a 03 CD _ o a X X o d c3 03 03 —I-* 3 ‘-G O o 03 (-1 k—1 hM W Q Q «— fa > TABLE NO. A-7—Concluded. 246 FLOOD CONTROL REPORT. . 00 oo CO o »o CO o 05 00 O0 CO CO CO 05 T— H CO CO CO H-5> ^H tO t-H T-H CO iO CO CO CM £ tH T-H ^H t-H T“H ^H T-H T-H T-H ^H T-H tO CO to oo 00 05 CO oo 05 CM CO CM o to cm CO CM CM Tt< 05 CO CO to 05 o CM oo 05 o o oo 05 o CO T-H tO T-H CO d Tt< T-H CO o T-H ^H ^H CO o CO T-H >5 05 T-H CM CM o c3 05 05 o oo 05 00 oo CM § d ^H © ^H t-H ^H t— i tH T-H T-H 05 to CM T-H 05 iO t-H Tt< ^H 05 tO tO CM 05 o CM ^H o CM T-H T-H t-H o ^H T-H T-H 05 o 05 o o oo CO oo CO o o CM to CM CO CM rH o Tj< o o o tO o ^H o o ^H ^H Tt< CM T-H T-H t^ o T-H d ^H © ^H o - 1 o - 1 o t-H o ° ^H o rH d o • > < CO CO 05 T-H o 05 05 CM Tt< 05 CM o 05 CM o o o a C H t-H ^H o ^H T-H o T-H T-H ^H t-H >5 ci CO CO CO T-H CO oo CO s o o © T-H o o o o o o 1 d d d © o o o o o d o 05 T-H CO to —H tO t-H Tf CO CM o oo CO CM oo CM T-H oo to to to CM 05 »o CO 05 o oo o T-H oo CO ^H 00 to to CO CO o CM ^H CM t-H CM d CO tH CM T-H o CM CM T-H cq CM T-H P March. 05 00 CO 'rf o to d TH © T-H o T-H o CM o o t—H 1 d o © d o o o o o d 05 tO 05 00 t>T 05 CO T-H CM T-H tH T-H CM 05 (M t-H T-H • © tH ^H T-H T—H T-H o o T-H ^H T-H a 05 CO CO o t'T CO CO l>- CO lO CO o CM to to o o CO cm CO tO CO CO CO to 05 lO tH CO 00 CO tH i-H CO iH CO ^H CO ^H CM lO CM CO T-H CO CO T-H c3 05 o o T-H T-H ■~v CO —H CO CO tt* CO CO T-H T-H CO Jh d © d o o o o o o d © (h Tt< CM CO to 05 CM o CO o tH CO CM CM ^H ^H T— ^ CM CM T-H o o o CO CM CO o o CM , o 05 o 05 o 05 o T-H CM CM o CO o T-H o o CM o 05 o CO o oo o oo o CO o . T-H d t-H d T-H d T-H o — o T-H o o t-H o t-H o t-H o K*5 Jx ci CO 05 CO i-O 05 CO T-H o CO 05 CM oo 05 CO o CO CO o c o T-H o rH o t-H T-H ^H t-H c3 >"o CO CO CO CM CO oo 05 CO CM CO CM CM CM to CO CM CM CM o o o o o o o o o o fH H-> tO CM CM CO 00 CO CO CM « G P-l o CO 03 o c3 © © . o o tO o fcO o o o o to c3 © oo tO v-H CO lO CM 00 o CO CM tO 05 CO 40 o t-H to oo to p . - a g t-H T-H T-H CO ^H T-H ?H ^H co k *"■* tH T—H 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 * 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 • 1 1 1 1 1 >. 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ■ 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 © 1 1 1 1 1 Watershed 1 1 1 ja 1 JS 1 1 1 1 1 .2 *c 1 1 1 I c3 a gJ ci > a 1 1 1 1 1 1 1 1 1 1 1 1 HP p o £ © > c X ci m d ►J o -*P m *c u> o m c3 hp © > o © P. o -*-5 © *c3 m 1 1 .2 *c o © Ph © > o > c3 ffi o -p .2 8 © © Fh o © > o Xi c3 1 1 -2 ■> © m © > 1 1 ja +3 G o s ci c c3 > c3 K 0 > o c .2 s CO X ci 03 QD tO c3 (Tl &H a JO 63 CQ • a o o o o o Gj! o c c a c c G © o o G © IP IP 'rP IP g3 Q* Q, »H > t-H HH HH H s m 03 HH 247 APPENDIX “A.” 05 t'H. -- tO 05 r—H 05 CO T-H 05 CO 05 CO CO T-H 05 05 CO M 05 05 CO 05 ^H T-H T-H 1—H T-H ^H rH T—H CO M CO CO 05 CO to to T-H T-H T-H 05 CO CO o o OO oc M o to CO CO 05 CO oo M CO 05 oo oo o M - 05 oo CO T-H o T-H © ^H CO M 05 CO oo CO T-H CO CO M 05 to CO M 05 to 05 to CO M 05 M 05 M 05 M 05 05 M CO CO 05 to M CO M 05 05 05 CO CO CO CO 05 o CO © © © © o o o o o o tO M o T-H 40 oo CO 05 to Ml 05 oo oo oo oo oo to 05 oo 05 ^H T-H T-H T-H T—H T-H T-H T-H T-H o t-H o CO o 05 05 05 o CO o M T-H o ( o to T-H o o tO o !>• o t-H o 05 o T-H o 05 o oo o CO o 05 o 05 © © © © © tH © T-H o 05 o rH o o o O o o CO CO CO CO to M CO to CO Mi CO 05 05 o oo to o tH o o o T-H T-H T-H o o T-H »o to o T-H M 05 o 05 T-H 05 © T-H 05 o M 05 o o 05 © © © © o O o o o o 05 o 05 CO CO M CO M CO o T-H T-H OO 05 o T-H to o to to o to O o to to oo t-H CO oo 05 CO o M M M M CO 05 CO 05 oo T-H 05 to CO T-H t-H CO OO 05 05 05 1 1 1 1 1 1 1 1 1 1 1 a i i i i i i i i i i i i t 1 1 1 1 1 1 1 1 1 1 1 i i • i i i i i i i 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i i i i i i i i i i i 1 1 1 1 1 t 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i i i i i i i i i i i i ii i 1 i 1 1 i 1 1 i o » ‘ >5 m n3 H c3 O « o 42) i a o -4-5 u > • FH P5 1 1 t X 3 o a i Cl E* o -t- m 73 H c3 o3 0) Ph o a & o -Q • i i i i i 1 • 1 1 1 a o 42) «4-H c3 Ih o a as W 0) > o x> aS i i 1 i i a o 42) *4-4 c3 cS a © > o 4) > O os W X eS a o a -Q aS a o O > o X ci o a> (h o 0) > o Xi as cS o to ® > o X aS rn a n cn ao O CD m GO ~o a • rH aJ M a c3 M a "o O -S M o o o a "o _a 3 O O c3 • rH O a k-H CO «3 ►— 1 M o >-H ►-H s k—H r-H 05 CO M to CO 00 05 o 05 05 05 05 05 05 05 05 05 CO TABLE NO. A-8—WEIGHTED AVERAGE TEN-DAY PRECIPITATIONS ON ILLINOIS RIVER WATERSHED. 248 FLOOD CONTROL REPORT. • 05 o 40 05 00 CO CM CO 'S -4-5 N O •o CM 05 CM d oo 05 05 05 05 d OO 05 oo CO H CM rH rH CM CM CM rH rH CM 40 CO o 105 40 CO CO CM CM 05 CO CM CM 05 co OO 40 40 05 00 40 CM CO oo 05 o O rH 05 40 05 CO CO CO o CO CM © CO rH CO r-H 40 CM 40 CM CO rH CO CM CM co rH © CO OO 00 r-H CO N o CM G 05 oo 40 OO CM rH OO oo CO 3 © d © r-H rH r-H rH d d o 05 CO o CO r^r o co oo oo rH 05 o CM co CM rH CO rH o rH r-H »-4 rH rH o rH r-H 05 05 CM o o 05 CM ^H CO OO 05 40 o 40 05 r-H co OO CO CO CO 05 40 CO o rH 40 CM CO 40 CO CO rH CM CO 40 rH CO © iH CO rH CO r-4 40 rH rH CM d CO rH CO rH CM o i-H o OO OO CM o CO 05 CM CO CO 40 40 CM 05 CM 00 r-H s CO CM r-H ^H CM CM rH rH CO oo r-H 05 CO 40 r-H CO CO OO CM © oo CO CM oo 40 CO CO £ o o o o o r-H o o o rH ►“5 05 CM r-H CO r-H o rfi 05 40 o r-H CO CO 05 1 00 05 05 CM CO CO CM 40 CO CM OO O 05 CO rH 05 . rH o 1—4 o rH o O i—* o CM o rH o CM o rH o CM rH CM CM 40 o o CM r-H CO 00 CO CO 05 CO CM CM o CM a <2 O d © d d rH d P rH rH c3 o 1—1 CM TT 40 05 OO CO CO 3 CM CM CM 40 40 CM CM CO rH G d © d d d d d d d d rH 40 r-H 05 CO CM r-H OO o 40 r-H 05 CM oo r-H co' 1 CO o 05 r " H CO 40 OO r-H 40 00 o CM CM 05 oo 1 ^*"1 CM 40 r-H CM rH 40 -H CO CM '■* rH CO r-H rH 40 CM o 40 40 o CO CM 05 o co o CO oo O 40 CO 40 CO © c3 W-H rH CO CM CM CO CM CM CM CM CM rH r-H 40 CO CM CM O Tt* 33 40 CM CO CO CM 05 CO rH CO CO o o © d d d d d d d d d oo CO CM CM r-H CM CO CO cO 05 CM CO CM 05 05 CO cO CO o' p . oo *—1 05 CO 05 CO 40 CO CM r-H r-H o CM OO r-H CM rH 05 rH >5 t- rH © d r-Tl d CM d CM d CM d CM d rH d CM d rH o c3 40 CM o 05 o 05 oo CO CO 40 G 40 rH CO 05 05 OO CM CO u. • • • • • • • • • • X rH rH r ~ t r-H rH r-H r-H rH rH © oo 05 TJ4 r-H OO CO r-H rH CM CM CO rH CO rH © © d d d d d d d d oo 05 05 CM 05 CM o CO 05 r-H o 05 CO o 40 CO ■rp rH 40 05 o o CO CO OO CO CM CO CO CO CO o CO >. CO CM CM © CO CO r-H CO rH CO rH CO rH CM rH CO CM rH t-t ci G 40 oo r^- CM CO CO o CM 05 r-H 05 CO CO OO o O oo CO 05 o G © rH rH rH CM CM rH rH d CM c3 rH CM co o 05 CM rH i-H co CM *”5 CO CM CM r-H o r-H CM o o © © d d d d d d d O oo 05 oo CO 40 40 00 »H H-5 © G r-H CM © c3 © Ph © © © . 40 40 o 40 o 40 40 »o o 40 u oo 05 rH CO CO co CO co 40 < o3 © rH CO o oo TJ1 rH 40 CO 40 o GrG CM CM 40 r-H rH rH CM r-H O' G TO c 1 1 1 1 1 X ' i i i 1 -4-3 • 3 ! 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 o , £ : i • i i i l l l 1 > i i i t 1 1 1 1 1 1 1 © i 1 1 1 1 1 © i i • i 1 1 1 1 1 1 > i l i 1 1 1 1 1 1 & : i i i -a ; 1 1 1 1 1 G . i i i 1 1 1 1 1 1 c3 ' • i i 1 1 1 1 1 1 1 1 t 1 • « : i • i 1 i i 1 1 1 1 1 1 « © i • l • 1 © . 1 1 1 1 1 c ■ i 1 i 1 © A © 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 • 1 1 1 1 1 1 1 1 1 c3 , S ! © i © i i i i » i i l l i • i i i i i ( I 1 1 1 © -4-> 1 1 1 1 (h 1 1 1 1 c : i i i i i i 1 1 c3 1 © © g © a c2 1 1 ■ • i 1 £ © CD a c* Sh © -*x 1 1 — _© 1 J3 3 «— c — ! i I i i i i i i « 1 • i i i Ih o -4—3 c3 X G o © o o o d ; © G i © i- jG s o c © > c t Ih Ih G C G -*-3 o © © > E A o G o © © > o JO > > o o Ih 03 CU Ih s o > o x cS o X S3 .O a m rO c3 © © > o fcfi < © £ o X of c3 © © © © © a © G -O © > © > G 3 6.07 APPENDIX “A.” r» CO oo to to 05 CO CO o o tO N CO CM CM N oo to CO CO CO rH CM to CO oo oo CO CO oo CM CM CM CM CM CM CM CM CM CM CM CM N CO CX o CO O CO CM —i N 05 N to "*V CM to CO CO o oo CM CO 05 o rH CM CM CM o CM CM CM 05 rH oo CO CO rH CM CO oo CO to Tf* oo CO rH tO CO CM CO rH -H CO rH CO o CO CM CO CM r-H *•** ^H CO o oo rH CO to OO CO to o 05 to CM CO 05 to o to —H o 05 o o o o o o o rH —< o CO oo o 05 oo o CM CM ■**» Tt< CO rH oo oo r>* o co rH rH rH rH 1—• — H *-< CM CM rH CM rH CO rH CM o co to 05 CO CO CM oo CM rH OO oo ■*v •*r OO CM oo CM CO to o 05 CM 05 o CO rH tO o oo rH rH CO to to to CO CO rH CO i-l to rH CO rH 00 CO CM t-n CM to rH r-H col CM CM to o o CM CO *H O to to CM CO CO oo to 05 to CM CM rH o rH CO CM CO CM CO CO CO OCO’^^COCMOCM'rf'tOr-i CM C0000005GO*-HCO'^’Tf«Oit^05 rHOOOOrHrHrHrHOrnO oo 05 05 05 OO o 05 CM tO to CO CO CO CO rH CO oo OO o CM CM CM 05 CO CM o rH o oo o o CM oo oo CM to o CM 05 CM 05 CO 05 05 tO O to CM rH CO r-H CM o CO rH CM o CM rH CM rH CO o col © CM © CM -H CO rH CM to CO 05 CO OO CO to CO CM 05 CM CO 05 CO o o o o 05 rH 05 GO *—• rH o rH rH rH rH CM rH rH O O t^tocMc^^rH^ocMcorHcx rHCMCOCOCOtO”*t O CO c« O o © > xi © cx o £> as *C Ih o © > o 13 m 03 > o a _o X x 03 X rQ 03 rH CD ao CD © fl o o o o □ Ih a fl a a HH hH XH >5 © 1 c 3 c 03 > i i • i 03 a l • > © i • c 3 a 3 © i i G W Ih a © rH -*x cl > o © > © O 03 w c 3 O m a Ti o X 03 © > © > © > o Ph arl f£ 03 fl o X 03 o X c 3 X 03 "o B 3 © a) hH fl O O a m C o o a m '5 a rH HH c z o •*-> c d 'TJ u a3 © « as a as > as X o a e o u* a> > « o XI a! a c a cS S) a c3 CO CM CM 249 co GO 05 o CM TABLE NO. A-8—Concluded. 250 FLOOD CONTROL REPORT. • CO oo o CO T-H to o CO o oo CO CO -+P> oo TP o CO to OO 05 to H CM CM CO CM CM CM CM CM t-H »o 05 tP CO oo 05 _ r- O CM 05 CO to oo oo T-H CO o T-H CO co CM to rf 05 05 to CO o tP ^H to TH CO o ^H CO o CO o T-H CD rr CO r-H oo CO ! <| o t-H -J ^H T-H T-H 03 tO CM o to CO HT> 05 oo d to Tp o CO Ttl OO c o o t—H o o o o o o T—( V-H O n to CM o T-H oo CO o 05 05 o CO tP CO CO TT CO CD d CM CM (M CM CM CM CM CM oo CO to oo CO CO CM "d CO Tp CM oo rr CM O o o o o o o o O o o 5 o 05 TP > •*r T-H tP t*H CO fH to T-H to T-H T-H c3 o CM T-H 05 oo CO CO ,-H TP T-H O o to T-H a CM c3 ss » i i i X -*-> 1 1 a £ o T? c3 CD Ph o >> a> • H P3 i i i • i i 1 1 1 1 t 3 o ® 3 as M © i 1 i i 1 i t 3 -*-> 3 o s TJ cfl 3 £ > o s* t •c c3 3 h a o X as o -*5 c3 ® > o JQ CS 3 O a a> « a> > o X OS SO Ih c3 O X as O H-> cl Ih O .5 •g, Ih 0 ® > o X as P an CD D OQ CD as bD a • M o •o "o "o d o • «H o 3 3 O 3 3 o c3 3 C3 , - 1 Ih j ’~ 1 | , j d m HH h—( O HH t—1 s ►—1 CO Tp to CO OO 05 o o o CM CM CM CM CM CM CM CO TABLE NO. A-9—WEIGHTED AVERAGE TEN-DAY PRECIPITATIONS ON ILLINOIS RIVER WATERSHED. APPENDIX “A.” 251 • CO CO CO CO ^x O OO O CO c3 o CO CO O T—X 05 kO CO kO T-X CO T-X d d CM 05 05 y—i £ CM CM CM CM CM CM CM T-X X CM oo CM kO O kO O CO 05 CM !>• 05 oo CM is- CO T-X kO r- CO kO T-X T-X o rX o CM X CO ^x o o CO O CM CO kO CM OO CM o o y—< o X o CO O CM O T-X o T-X O CO o CM o o O CO oo oo N OO CM OO o oo 05 05 T-X kO CO T-X d o o o o o O o o o O o t>- IS. o 05 N kO o CM CM CO CO T-X CO oo 05 o O O CM X o o CM T-X O oo kO kO kO OO kO CO 05 CO CM kO kO T-X T-H CO 05 CO T-X CO o CM T-X CO o CO CO o CO OO o CM T-X co T-X O T-X o O ^X o CM o T-X o Tf« o o y—i o CM O O o X o © CM kO oo o CO 05 CO d CM T-X T-X X CM CO kO kO CM o o o T-X X o o T-X —X O r-i kO kO CO CO CM OO t-X 05 OO T-X CO OO y-i T-X T-X CM CM T-X X CM CM o • CO r-H CM T-X **P kO CO CO OO o 00 X' CO kO o CO CO kO 05 t-X 05 o T-X CO kO T-X T-X ^x T-X o kO 00 T-X o 00 T-X 05 CM oo kO CM CM CM CM T-X CM ' CO y—i CO CM CM o CM O CO CM CM kO OO kO kO CM CM T-X c3 CO o kO kO 05 T-X OO OO T-X 13 £ t-h y—i T-X d d o X d d T-X ►“5 CM CM T-X CO i^. 05 CO co O l CO OO ^p Tji TJ< kO kO CO 05 o d O d d O O o o o o IS* CM kO kO 05 o CO CO ■Tt 1 r^- T-X CM o ''P CO OO CO r-H kO 00 tx. kO CO oo 05 oo CO o OO ^x CO 05 05 CO lx ci CM* kO CM CO CM kO CM kO CM kO CO CO CM kO X T-X co CO CM CO CO t-X co 05 CO o e« a CO kO kO CO co CO CO kO OO < CO CM CO CM CM ^x CM CM CM y—i ! t-h OO CO CM t'- CO T—X kO 05 CO CO CO CM oo kO OO kO CO o d d d d d o d d o t-x In (D o CO T-X o T-X CM OO CO CM CO o t-H r- o 05 T-X CM CO CO OO T-X CM CO 05 OO o Th OO kO oo o o cm! T-H CO T-X CM d cmH d CM d CM o CM ^x CM d cmI o CO T-X o O O o co •~r CM T-X 05 05 •rp O o oo CO rt< kO CO kO CO s c5 *X d d d d o d d d d d T-X CO CM oo o CO co o y—i oo 05 O o o T-X T-X CO y—i T-X o o T-X T-X x ^X T-X T-X CM oo o o oo T* 'rfi O o kO T-X OO CO kO xf CM CO CO T-X T-X X o CM CM kO kO CO o CO CO CO o CO lx CO y—i y—i o rX CM O CM O CO o CO O T-X o T-X O o c3 t-X CO CO OO T-X o O CO d OO oo CO OO OO T-X CM T-X kO X y—i o T-X o o T-X X o o T-X © 'rP kO OO CO CO OO CO CM oo pH o CO T-X T-X o co kO 05 CO o CM T-X T-X X ^x o o T-X T-X CM "e* CO CO t-H oo t-H 'Tf' O r^. 05 CO CO 00 kO T-X CM CM 05 CM oo T-X CM o CO 05 05 kO oo CO >> H d CO rX CM T-X T-X T-X X CM X CM d T-X d T-X d T-X d c3 oo CO OO O CO OO kO co CO CO T* oo kO OO CO kO a o t~« o O o o o o o o aS CO kO CM CO T-X o 05 »o CO CO CM CM kO kO T-X kO o o o o O o o o o o 00 05 oo CO kO N kO oo kO t- -*-» o a X CM CD Ph © o © Square miles. kO kO O kO O kO kO kO o kO lx oo 05 T-X CO CO co CO CO kO < T-X CM CO CM O kO oo X X T-X kO CO X kO CM o X i i i i • 1 1 1 1 1 l c ! 1 1 1 1 1 1 1 1 1 1 as ' • 1 1 1 KX 1 1 i i 1 1 1 r- i . i 1 1 1 1 1 I 1 CD l 1 © t c > c3 , i i i t 1 1 1 1 • 1 £-2 1 • 1 1 i • X 1 r qOi 1 • • 1 r Td i i © lx c3 ru lx I i i • 1 1 1 1 • 1 1 © M i i © a © d « 1 1 X •gS 1 1 1 1 • lx o CD lx i © CD © -p _o 3 X CD l X 1 t 1 •P c3 © 4-5 o OQ d > 1 o o a 30 00 d • »H • 1 © lx c3 & 0 as X) © s > O ® > >“o © > o a © > o C £ ° X fc o £ 3 cr 3 o a o lx x-> c a © > M o 4-> o X as o X aS X as ID X as O 3 2 2 © > o U) « ■ < <1 © £ o X as a © © © © ■£ 8 n © © 3 © © a 0 1- as > > •X X • |X CJ *—X CU • ri 03 £ 00 «xx X © O ^X CM CO kO CO OO 05 O TABLE NO. A-9—Concluded. 252 FLOOD CONTROL REPORT. _ * © © CO CO © ^J 4 CO CO CM CO CO CO © y—t oo 00 o o © © © p CM y—* CM CM CM CM CM CM 05 o CM © CO CO CO © © CO © © CO oo © © oo oo oo CM © © © 4 " H CO TT VH CO CM CM © 00 CO © © CM c> © — n © ~n © © © CM © -T| © CM~i © «-H © >> CO © «— 1 oo © ”*r © © F-H © TJ 4 *— < CO CM CO y—* CO o © © © © © © © © © CO © CM OO oo © y—, © © © © oo CM CO © o © © © © © © F—< © F—* CM © © CM © © OO CO CM © OO oc © © © CO © o o CO CM © CM © © CM © © oo CO © •^J 4 © — © CM © CM © CO © CM © CO © — © © © CM © d CO © CO CM CM CM © © CM © © © CM © © oo o © © *—< © CM *—• © © © © CO CO CO oo © Tt 4 CM F"H © © ^J 4 © © © F- CM © © © F-H CO © OO © © CO Tf* © © CO CO CO © © © © 00 © CO © CM CM © © 00 00 CO © •O 4 00 o6 CO — CM © CO CM — CO — CM CM © CM CO CM col © oo © © © oc CO © c3 CM © © oo © CM © © © ”3 — < © ▼“H © © CO © © CO •*T OO © oc oo © CO CO © © © © -O 4 CO © © © © © © © © © © © © © TT 4 «C 4 CM y—, © © _ CO © TT 00 © © © - © CO 00 00 © CM © © © CO CO © CO CM CM o"1 CO © ^H © CM ©n CM © CM 00 CO ocTI CO © CM © CM © CM a f-4 r- © *rr 'TT © © © -O' 'O 4 © CO CM CM CO y-^ •'T © © < — CO CM CO CM ^J 4 -o 4 CM o T* 4 © OO Hf 4 © © 00 CM © © CO CM CM c p © © © © © © © © © L a o © © CO © CO CO © © CO © © CM © © CM TJ- 4_H CO CO oo © CM oo © CM © © © oo © oo © © . CO —< CO ^H CM — < CO CM — < CO CO © CM © CM © CM o ko i>- © © oo © -O' © o CO © © © CO -O 4 © fe © © © © © © © © © © o © CM CO © © © oo CO *— i F-H © 1H © CO CM CO CM y—* y-^ »— 1 CM CO CO CM OO © © CM © ICO CM © oo © © © oo © © CM © © © © © © oo © >i CO o CO © CO © CM © CO © © CO © y—4 © © CO © Cu __ r— © f J OO © © ^J 4 y-^ y-i CO © © © CO CM © © • • • • • • • • • i < ■•— 4 © T-H y—* o CO © © oo oo © CO © F-< — CM © © 05 © __ CO © © © -v © © CO © CO CM 1 oo CO CM © © © © © CM © © CO CO © © oo >> © CM — CM © © CM © © © © © © S~ © © rv> © © © © © r— < CO © © © TJ 4 CO CO © CJ © © © © © © © Q © © c3 CO CO © © CO ■n 4 CO ►o © © CO CM -t 4 © © © © © © © © © © © © . © CM CM © oo © © CM t_ — © ® c P o OQ O c5 © o . © © © © © © © © © © oo © © © CM 00 © CO < fc- CC c3 O CM © © © © © © oo © ^ ' ' CO T*H 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i i ■ i • i i i i i i i i 1 • 1 1 1 1 1 • 1 1 1 1 1 1 1 1 1 1 1 • 1 1 1 1 1 1 1 1 1 1 1 • 1 1 1 1 1 1 1 1 1 1 i i ■ • • ■ i i i i • • i i • 1 1 1 1 1 1 • 1 1 1 1 1 >. 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 • 1 • 1 i o 1 ■ 1 1 1 i zz a o 1 Q 1 c3 1 c3 > 1 1 1 1 J3 1 L c3 1 1 1 Z -p> G o CC cS 1 £ o o t 1 c3 > c3 Cj o u • 1 o 1 1 cS c a —i — * o > *-3 O -*-> CD CO =3 l-P o -2 o o A hH o -*-> ci o © o ■> o CC -4- G o a > ci HH HH =3 c o L' (-« o S © > Q JZ c3 a m — » o > o3 0 O PH c3 £ c3 o > o ja C3 © > o ja c3 & > o x> a OQ OQ 03 CC C G CD . ^ 0 d c O o o o O o o O c e c z G o o o c o I© ' ~ c3 o. Q. > P = — — s CO m O CM 253 APPENDIX “A ” D D CO CM CO 40 CM o *o oo CO CD oo D D V-H CO CO 40 CM v~* CO oo CO CO cm CM CM CM CO CM CM CM CM CM 40 CD OO rr CD CM CO o CO oo »o o oo oo CO CO oo o CD 40 OO CO oo oo 40 40 CO oo oo CO O o o —« o CM o CM © o o —• o — o CM oo CD r—i CM o oo CM CO o CO CM CO CM *"■ CO © © © © © © o o o o CO © _ CO _ T-H CO CO CD 40 D D oo D r-4 © © © — o o o o oo CO rf« oo CM 40 CD CO 40 CO CO D oo 03 40 t>» o CM CM CO r-H o 40 oo CO D CO o CM o CM o o CM o CO CM CM o CM o CM OI CM o 40 r— o oo CO CO CM © 40 40 40 CM y—< 00 © o © © o © o — o CM »o CO CD CO CM o CM CM CO o CO ^■H y* CO CO 'TT CO *-' y-^ D oo CO oo co CM CD y-^ CO r—i o D D oo CO CM 40 CD CM CO CM o CM 40 40 o o CM 40 to CO 40 CO CO CM oo ■*r 40 *** CM •**< CO CO CM a—* CO CO CM CM oo oo o CO r-H o CM y* *-« CO —H o o o OO 40 o CM D o CO 40 CM CO 40 D o 40 CO 40 40 © © © © © o o o o o 40 CD OO o o 40 CM © CO CO CO 40 40 D oo CO D o 40 CD oo CD D CO CD CO CM oo CM CM o CO o D ^■H CO 00 CM © CO D CO CM oo CO CO D D CO ^■H CM r—< 40 CO CM CO oo CO D O CM 40 y—i o o CO CO CO CO CO CO CM CO o CO »o CO oo CO o CD o CO 40 o CO y —< O CM »—< *—4 1 o 03 *—• CM oo o 40 OO CM oo CO D 40 CO D TT r>- 40 o CO 40 40 CO o , " H o 00 oo o CO CO 40 CO CM CM CO CO *-H CO CO 401 — CM — col *Tf< CM CM CO o CO CO CO o ’f »o o CO 40 o 40 CM 40 CM CM 40 o o o o o o o o o 40 oo oo o cO o o CM o 40 o rr o 40 40 o D 40 CM *—• CO CM tH 1-H to CO CD *—■1 oo CO D o oo r— 40 CJ 40 '*r 40 Tf **-H CO CM oo CM o CO CM 00 o D CO CM CO CM D CM © CM © CM © CO © CM © -H o CM o CM o CM o CM o o CO •*r OO oo *— < CM oo o o CM D o oo o • —i o ’—I o o o y* o 40 CD D CM '*r 40 oo 40 CO ■*r CO 40 ’—I y~i <—< o y—* «—• Tji OO CD 40 o CO CO CO 40 o D 40 CM TT o OO CD CM © CO CM 40 CO CO fH y—t 40 CO © o o o © -n © o o —<*l o — <*l o 0*1 o o o y~~* o CO CO CO CO o o ^5 CO '•f 40 CM CM 40 CM CM to o o o o o o o o o o CO CO CO o T-H CM CM oo CM CM CM r—i oo ^ 1 CO © © © © o o o o o o CM o CD CO o CO CO o *-h oo D o 40 o 40 »o o oo »—< CO oo CM CO CM 40 CO CM 40 o o 40 LO o o C^3 CO D oo y • y —( CO CO C3 03 1 • 1 1 • 1 1 • 1 1 1 a 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 • 1 1 1 1 1 1 1 1 I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 £ 1 1 1 1 1 1 » 1 o 1 1 1 1 00 M s o « o 1 a o h « > s 1 1 1 J2 -4-J 3 o a 1 a £ o -*-> ao "O u a c3 0) Ph o -4-^ a £ © ■q. £ © > o JD 1 1 1 1 1 1 I 1 Ti 1 1 1 o «4H c3 u a G 1 1 1 1 1 G o +3 44-1 o3 as a oS © > o £> © > o o o o o -*-> 02 T3 c3 a o Ph o o t- Uh a a> > c3 w C3 c o a c3 o o e > o -C cS aj rt 1/ « ao Ih o T3 © > o J3 cl aj c3 o (*N MH CO o '3, > o G CO "o a c5 60 CJ M o G o a o • *1 o c "5 •y G o o "3 c • I—1 • ^ • —* ci • ^ s CO CO a s o NH 4—1 fc-H s CM CO -r 40 CO h. oo D o CM CM CM CM CM C3 CM CM CM CO TABLE NO. A-10—WEIGHTED AVERAGE TEN-DAY PRECIPITATIONS ON ILLINOIS RIVER WATERSHED. 254 FLOOD CONTROL REPORT. 05 05 05 OO 1C 05 o ic rH rH CO oq CO CO o r-H oo o oq r-H o CO oo o CO oo CO 05 o H oq oq oq oq CO CO oq oq oq CO O 05 »o oo CO 05 05 05 CO oo oo oq r-H 1C CO 04 to ic o CO oq T* ic 05 o 05 05 CO rH co o rH N CO CO HP ci" o Oq © oq O r-H © Oq o r-H o oq~1 O CO oq oqi r-H r o oo ic 1C rrr 1C 1C oq CO oq CO r-H r-H r-H CO o o o bfl • • • • • • • P o o o o o o o o o o < CO oq oq Tf oo o r-H ic co CO o CO oo r-H oq oo o o rH r-H *—< o o r-H r-H o rH rH co o v-H OO co iP o oo oq 05 CO CO r-H CO oo or. CO o' *c CO ic oo 1C oo Tf« 05 05 CO CO CO CO o L- 05 rH o oq o rH o oq © CO © CO o oq o 04 rH CO r-H CO o oo o oo CO oo r-H ic o CO Oq oq oq oo IP co ic 1C P o o © o © o o o o r-H oo CO ■Hf CO 05 CO o CO CO ic ic o iC 05 Tt< o CO o r-H r-H rH r-H oq rH r-H r-H rH oq CO co OO CO 05 05 OO 05 CO CO oq co o CO 04 o CO CO ic oo t'H rH ic CO CO oo oq o r-H ic o o 1C 05 rH oq 05 CO !““* Tt< r-H iC o oo oo oq 05 CO CO 04 Q) r-H r-H c co oo ic IC r-H oo ic 05 oo oo r-H CO CO CO oo 1C >-5 rH CO oq CO oq CO CO CO o o © r-H CO 1C 05 o CO oq Oq 1C CO CO r-H CO CO 04 © r-H © oq oq r-H rH oq Oq r-H iC r-H ■*-P T-H 05 iC CO CO oo OO OO CO oo TT oq TJ1 >c 05 oo © CO oq 05 CO oo CO o ic oq CO 05 O rH 05 04 OO oq !>• oq oo oq r-H isl rH o oq oo oq rH 05 04 05 oq rH 05 r-H ip iC oo OO co CO CO 05 Tt« t-r ic 05 1C o CO g • • • • • • • • • • • CO t'T O CO CO N ip oq CO 05 r “ H CO OO CO oq 00 1C Tf CO o 00 oq rH ip oq r-H oq oq oq r-H r-H r-H rH r-H oq r-H Oq 1 rH r—H rH rH r-H oq r-H r—H CO 1C CO CO l>- CO 05 CO o r-H o O o rH o o O r-H Cj HH o o o o o O o o o o CO r^. r-H oo t*. co CO CO CO CO CO ic o o O o o o o o o o oo 05 OO CO 1C 1C oo 1C Ph HP r-H oq © a Ph © O 04 05 oo CO P to P < i oq 05 oo pP o § I T) O • f—< u o a o o Ph oo c3 O Ph 1C ic o 1C o ic IC 1C o »c oo 05 r-H CO CO CO L— CO CO ic r-H CO o oo ip rH 1C CO ic o oq oq 1C r-H r-H !>• rH oq rH • pH OO ^ J2 pH • pH ? a T3 o pO o3 oo • pH o p cr o U. 1 i i i -p 1 P ! 1 1 i i i i i i o ; a • 1 l i t i i i i iT ! 1 i i i O i 1 i i i 44 . c3 • 44 i 1 i i i a ; 1 i i i c3 i M i 1 i i i ph ; 1 i i i co ! c o > 2 O 1 > > o o ^ Ph o & ■^Ph O pO O pO pO o3 pO 03 c3 c3 CO co CO STt o pP a 00 • pH O a U4 o HP <3 to 0) O < pP 03 (D © rH > > M Q O o • H pO p • pH c3 C3 a M X M Ph O O O fe > O o APPENDIX “A.” CO g ,_, CM o OS iO O r-H co r-H OO CM oo OS CM CO Os OO o CO o> d OS OO •rp CO CO ^p OO CO CO CM CO CM CM CM CM CM CM CM CM CO r-H l>- CM os • G CO CM CO OO CO H rH kO o G TjH CO CM kO '-P kO 00 G G Tt< G vH o d o CM o ^H o CM o r—H © r-H O o r-H o — O O o CM~1 d CO o t"- CO r-H r^. r-H r-H CM o G o o CM o CM CM o CM CM CM o o d d O d © © o O O o o d oo CD oo CM CM r-H CM CM r-H CO OO oo o O OS o os G O r-H o o r-C o r-H O 1 o O ▼-H O CM CM 1 05 CM G •rfi o o kO r-H r-H r-H r-H OS r-H OO CO *o G O r—H o G CM g CO os r-H o o CM os o OO o r-H 00 G G kO CM o o CM O d CO © CO r-H ■^H —• > CO kO r-H oo CO G CO G kO OS CO oo CM oo o CM r—H - CO r-H r-H OO G o OO CM OO o os O G G CO G oo G TfC CO CO CO CM o o CO CM CO r"- kO oo CO CM r— r-H OS G o G r-H CO CO kO T-H CM oo r-H XT CM r-H CO kO XF o CO OO CO oo r—H G kO CM g T-H CO T-H r-H -*p r-H - CO o CO r-H CO o kCO o r-H G o CO CO CM r-H r- G CO G o O kO o kO CO kO TJ< CO G G r-H o r-H r-H r-H (M r-H CM CM r—' CM r—H CO r-H kO »o CM CO CO kO OO r-H CO r-H (M CM kO r-H o CO G CM r-H CM CM CM CO CO CO CO CM CO CO G r-H kO OO kO G o ip o CO oo os o CO o Tt« o CM G CM G CO kO o CO CO G ts- CO CO r-H kO o r-H G r-H CM G r—H CO G G O rD c3 G O a 0 > a co a Uh Ih O s cn • H o 03 CO c3 hP CD > O rO c3 O D Ih o 0 c3 CO e3 # 0Q O Ih o CD Ph 0 > o J2 c3 O fl oj G o3 > c3 a o •4-d o3 • ^H Ih 8 P-, cn O ^S 0 1 1 1 1 1 1 i l i £ O 1 1 1 ’c3 > 1 1 1 1 1 1 l l l l d o a 1 1 l c3 M 0 1 % 03 0 0 0 M o 0 > o 1 0 T—H > 0 m 1 rC H-S P o a a oi > c3 w « O a fl > • H a © > o rD a 0 > © > 0 > o o3 > c3 Xi 03 & c3 fl o rQ a o x> 03 X> o3 CQ w OQ a o a O c3 § fl o o Dr CO c o o o. CO • rH o a 3 M • rH O 0 • rH h-* 03 to a 03 CO CM CM 255 co oo o CM TABLE NO. A-10—Concluded. 256 FLOOD CONTROL REPORT. CM 03 oo CD G fcJD CM 03 CO o Fn G § r3 .2 © a o o • o CO O CO ^“4 to G CM ^H o i-^ o CO 1—4 • o oo CO oo 00 H CM CM CM CM CM CM CM CM 03 Cl id to CM 1—4 CO CM 1-4 03 Cl CM CO 03 c© oo CO 00 CO 03 i-H CO to CO -4-3 Cl o o o o o o 1—4 o o o *- 1 o ^4 o to oo CO CO o ^H — o — o W) • • • . G o o o o o o o o > o c© to 03 CO CM oo 03 03 o o to o o *-* CM *-* ^4 TT* CO 03 1—< CO co CO CO oo CO oo CM CM *—* co CO 1-H tO oo oo CO 1—1 CO to oo »o -H CO CM t© CO CM oo CO CM CO CO 03 to 1-H CO o CO CM *• ° CM - ' o CO CM CM o CM o CO Cl © G 1-H CO 03 CM CO —1 oo CO CM Tt< O CO CO 03 >"o CM CO o 4-H CO 4 CM CO co 03 03 T—« 1—, oo l-H CO OO o oo o o o o —-4 o o 1—1 to tO CO CM 03 "Tf CO CO o oc CO to o oo o CO o to CO 03 to o *-* CO to ^H N CM oo CM OO CM CO oo CM 03 CO oo CM 00 CM OO CO CO 03 CO t>- o CO 03 CO r— CO to oo CO g • • • • • • • CM CM Cl CM CM CM CM CM CO o ■^r co CO to CM OO CM 1>- CM '■f CO CO CO c^ ■rr t© o "7< Tf o o to CM to o c© CO CO CO TT CO to ^H CO — »o —< © r^ - * o to CO o CO o to H rG 03 oo CO 'Tt* o to oo t- oo o o CM 1—< CO Q, ■ • • • ** _ 1 '-H CO CM *-< CO CO ' CM TT CM TT co o CO CM 03 to oo l>. CO CM CO co- CM CM CM CM 03 CO 1—, CO to CO o CM »o ■*v Cl i—i —( co CO CM CM to u ? CO !>. Cl to CO CO CM to - CM CM l-H ?Tl — CM — CM Cl Cl c» t'- oo •^r oo i—4 oo o o o CM o o o o G v—« o © © O o o o o s CO i-4 CO o CM Cl CO o CO 03 03 CO o o o o o o o o CD G © F-. © c ^8 CO oo CO o o o © . to to o to o o to to CO oo CM CO o a o TJ« o CM CO 03 oo *H — rr to CO 1-H CO 00 C* S CM CM CM a? CD Fh © 3 o £ © > o pQ G G O £ c3 t£ G 09 a) c & o -4-> CD "G - © e © > o pQ c3 C G u> 3 © pu, c £ ^3 Fh G o e o G >t © [S. S © > o po G © © T3 © O u o Fh © PU © > o pQ G 7? "o c c o w «4-. G t- a Fh o © Pu c G © G c3 w © > o pfi G © © F-. o a G O © G s c o iM G F-r a © > o pfi G ID *5 G © O co CM CM tO CM CO CM Cl oo CM ©3 CM o CO 257 APPENDIX “A.” TABLE NO. A-ll. TOTAL MONTHLY PRECIPITATION, COMBINED NORTHERN AND CENTRAL DIS¬ TRICTS, ILLINOIS—AVERAGE OF ALL STATIONS. Year. Jan. Feb. Mar. Apr. May. June. July. Aug. Sept. Oct. Nov. Dec. Total. Normal. 1.95 2.03 2.84 3.30 4.02 3.99 3.59 3.21 3.69 2.58 2.35 2.08 35.57 1856. 1.33 2.71 0.55 1.86 3.80 2.51 3.18 2.31 2.60 2.88 3.65 4.72 32.10 1857.. 0.62 4.80 2.87 1.21 2.64 3.34 2.14 4.62 1.74 2.25 2.57 1.28 30.05 1858.. 1.92 1.91 2.63 4.83 7.96 5.72 6.01 2.56 3.40 3.71 3.39 2.73 46.72 1859 _ 1860 .. 2.16 2.20 4.98 3.34 6.14 4.20 1.55 3.75 2.90 1.76 2.44 1.08 36.49 1861.- 1.34 2.51 4.08 3.79 3.22 4.16 2.59 2.06 4.26 2.86 0.93 1.40 33.18 1862. 4.70 0.75 2.66 5.88 2.39 4.67 6.38 4.44 6.11 1.66 2.15 4.17 45.94 1863.. 2.85 3.53 2.78 2.86 0.52 2.98 2.30 2.74 3.91 1.07 3.73 29.27 1864. 2.02 0.80 2.42 4.86 1.96 2.00 3.37 1.71 3.15 2.31 3.43 3.17 31.17 1865... 0.55 3.72 3.72 5.39 1.35 5.22 7.67 3.63 6.54 2.78 0.22 1.05 41.81 1866__ 3.13 2.00 2.27 3.21 2.84 1.81 4.09 3.84 7.45 3.49 0.52 2.50 37.14 1867_ 1.50 3.57 1.76 1.55 5.41 3.26 2.89 2.48 1.29 1.10 1.74 1.19 27.71 1868__ 1.08 0.68 5.89 4.87 6.51 2.39 2.74 3.39 4.21 1.45 3.79 1.79 38.71 1869.. 2.18 2.25 1.46 4.10 5.24 6.80 6.97 5.11 1.23 1.55 3.68 2.47 43.01 1870.- 2.78 0.96 5.29 1.12 1.53 1.69 2.50 3.99 3.68 3.97 1.56 1.52 30.56 1871. 3.64 1.81 3.27 2.35 2.36 3.66 2.63 3.29 0.61 3.30 2.61 2.35 31.85 1872. 0.42 0.97 2.51 3.12 3.26 6.38 4.91 4.30 4.11 0.67 1.28 1.09 32.99 1873. 3.76 1.22 1.00 5.57 4.92 1.78 4.39 1.20 3.11 2.63 1.65 4.93 36.15 1874. 3.12 1.47 1.52 2.82 2.53 3.71 2.50 4.45 4.41 1.53 2.48 0.85 31.38 1875..... 0.47 1.83 2.12 2.00 4.61 5.46 9.94 1.96 5.56 2.57 0.64 3.05 40.19 1876.. 2.45 2.07 4.16 3.52 4.40 5.32 5.74 3.90 6.91 2.02 2.52 0.33 43.31 1877...- 1.02 0.10 4.04 3.18 3.26 7.59 4.17 2.54 2.34 6.69 3.73 3.29 41.92 1878_ 0.72 2.47 3.32 3.65 4.63 3.42 2.97 5.35 1.30 3.24 1.14 2.41 34.59 1879.. 0.69 0.87 1.82 1.78 2.42 3.25 2.99 3.41 1.59 1.36 4.32 1.80 26.21 1880. 3.68 3.11 2.91 4.83 5.82 3.39 2.91 3.92 2.91 1.92 1.56 1.27 38.19 1881.. 0.95 4.93 3.51 1.96 2.15 7.12 3.08 1.37 4.62 7.60 4.94 3.05 45.28 1882___ 1.61 3.38 3.78 4.14 6.35 8.56 3.32 3.72 1.29 3.45 2.14 2.08 43.78 1883__ 1.56 5.71 0.95 3.78 5.55 5.05 4.31 1.29 1.40 6.48 4.30 1.73 42.09 1884__ 1.15 3.17 3.00 2.60 3.53 4.07 4.24 2.76 4.67 4.09 1.87 4.30 39.40 1885.. 2.74 1.38 0.33 4.33 2.76 5.31 3.09 5.95 4.77 4.16 1.54 2.75 39.08 1886. 2.85 1.62 2.83 2.68 4.27 3.54 1.08 3.51 5.29 1.39 1.75 1.17 31.96 1887__ 1.78 4.61 1.68 2.03 2.90 1.47 2.12 2.99 3.50 1.78 2.87 3.97 31.63 1888.. 2.15 1.84 3.20 1.86 6.47 4.18 4.54 3.06 1.67 2.78 3.59 2.45 37.77 1889. 1.84 1.50 1.52 2.15 5.19 4.99 5.03 0.91 3.70 2.11 3.08 1.71 33.70 1890... 3.91 1.94 2.51 2.63 3.81 5.12 1.98 2.37 2.41 2.93 1.82 0.60 32.02 1891. 1.76 2.21 2.85 3.50 2.09 3.63 2.64 4.83 0.94 1.21 4.51 1.63 31.76 1892. 1.66 2.19 2.33 5.84 8.80 6.72 3.96 1.97 2.30 0.96 3.11 1.80 41.61 1893. 1.26 3.31 3.17 6.39 3.98 2.84 2.03 0.57 2.90 0.88 2.20 1.62 31.11 1894... 2.14 1.90 2.81 2.33 2.91 2.56 1.15 1.65 5.18 1.17 1.91 1.58 27.27 1895.. 1.40 0.58 1.19 2.02 2.05 2.27 5.47 2.90 3.15 0.67 3.53 5.35 30.54 1896.. 1.07 1.82 1.39 2.96 5.03 3.66 5.20 3.30 5.88 0.98 2.18 0.45 33.89 1897... 4.98 1.49 4.43 3.68 1.83 4.64 3.34 1.13 1.07 0.32 3.83 1.97 32.68 1898. 4.13 2.09 6.35 3.00 5.99 4.08 1.96 4.58 5.09 3.85 2.31 1.30 44.69 1899___ 1.03 1.87 2.73 1.36 6.71 2.46 3.39 2.73 2.38 3.17 1.73 2.09 31.62 1900. 1.31 4.17 2.13 1.41 4.01 2.71 4.16 4.92 3.54 2.67 2.59 0.55 34.15 1901. 1.53 1.46 3.29 1.25 1.84 3.97 2.84 1.50 2.00 1.62 1.22 2.32 24.80 1902. 0.76 1.38 3.49 2.48 4.15 9.74 6.10 5.17 4.56 2.56 2.88 2.52 45.76 1903__ 1.25 2.57 2.51 4.70 3.50 2.84 3.86 4.67 4.63 2.33 0.96 1.56 35.35 1904. 2.72 1.20 5.18 3.69 3.43 2.62 4.89 4.09 4.88 0.61 0.17 1.61 35.06 1905.. 1.34 1.57 2.02 3.74 4.44 3.66 3.75 3.36 2.99 3.47 2.13 1.62 34.08 1906. 2.67 2.10 3.30 2.19 3.00 3.11 2.53 3.72 4.68 1.51 3.14 2.52 34.44 1907_ 5.19 0.29 2.99 2.61 3.62 4.10 6.40 5.40 3.05 1.17 1.79 2.14 38.73 1908. 1.18 3.75 2.84 3.99 8.33 3.01 3.12 2.60 1.35 0.70 2.52 1.15 34.51 1909.. 1.94 3.64 1.68 6.12 3.98 4.23 4.42 2.41 3.38 2.75 4.20 2.95 41.66 1910.. 1.98 1.33 0.32 3.30 5.47 1.99 2.88 2.70 4.29 1.82 1.14 1.19 28.39 1911. 2.03 2.21 1.76 3.98 2.06 2.59 2.86 3.84 9.43 2.86 2.91 2.01 38.46 1912. 0.72 1.38 2.78 4.56 4.34 2.70 3.48 3.43 2.55 3.76 1.90 0.81 32.39 1913.. 2.78 1.81 4.48 2.73 3.57 2.85 1.44 2.48 2.58 3.22 2.59 0.89 31.39 1914_ 1.69 1.61 1.84 2.00 2.79 2.92 1.45 2.80 4.07 2.56 0.53 2.01 26.23 1915... 1.95 2.13 0.80 1.56 6.65 4.27 7.50 4.89 5.04 0.74 2.25 1.83 39.57 —17 F C 258 FLOOD CONTROL REPORT. TABLE NO. A-ll—Continued. TOTAL MONTHLY PRECIPITATION, COMBINED NORTHERN AND CENTRAL DIS¬ TRICTS, ILLINOIS—AVERAGE FOR ALL STATIONS—Concluded. Year. Jan. Feb. Mar. Apr. May. June. July. Aug. Sept. Oct. Nov. Dec. Total. 1916_ 5.96 0.69 2.10 1.57 5.12 5.29 0.84 3.33 2.85 3.21 1.96 1.87 34.77 1917___ 1.34 0.43 2.73 3.92 3.95 6.06 2.70 2.30 3.01 3.03 0.25 0.72 30.36 1918_ 2.10 1.78 0.93 4.42 4.88 3.67 2.91 3.59 3.26 3.24 2.21 2.76 35.73 1919_ 0.31 2.06 3.27 2.44 4.87 4.33 2.16 2.67 4.10 5.37 2.99 0.53 35.06 1920_ 0.99 0.46 4.86 4.90 3.95 2.37 2.08 2.28 2.49 1.97 1.11 2.38 29.83 1921.. 1.26 0.48 4.87 4.98 2.01 3.76 1.86 5.18 6.95 2.74 2.80 2.78 39.65 1922__ 1.31 1.23 5.42 4.67 3.91 1.10 4.00 1.59 2.26 1.75 2.99 1.56 31.74 1923.. 1.12 0.95 4.20 1.77 3.73 3.55 2.05 4.17 4.16 3.81 1.52 2.92 33.91 1924_ 1.61 1.57 2.70 2.07 2.84 7.31 3.17 6.29 3.09 1.16 1.10 3.25 36.12 1925.. 0.51 1.74 2.14 2.75 1.29 4.76 3.21 2.78 4.69 3.29 2.46 1.34 30.93 1926_ 1.36 2.43 2.33 2.95 2.60 5.20 4.13 4.23 10.63 3.27 3.89 1.10 44.10 1927_ 1.53 1.64 3.85 6.41 6.56 3.74 2.72 3.09 5.35 4.21 4.33 2.56 45.95 PRECIPITATION FOR NORTHERN DISTRICT—AVERAGE OF ALL STATIONS. Year. Jan. Feb. Mar. Apr. May. June. July. Aug. Sept. Oct. Nov. Dec. Total. Normal.._ 1.74 1.59 2.60 2.88 3.89 3.75 3.30 3.28 3.69 2.43 1.97 1.71 32.83 1856_ 1.35 0.73 0.20 1.54 5.12 1.81 2.77 1.47 1.57 2.26 3.82 5.48 28.12 1857__ 0.42 4.89 3.45 1.40 3.23 3.36 2.69 5.86 1.53 3.03 2.29 1.21 33.36 1858_ 1.77 2.15 2.88 5.33 8.61 5.86 5.42 3.15 3.84 3.71 3.61 2.88 49.21 1859_ 1.68 1.17 5.69 3.19 2.99 2.25 1.14 3.37 2.52 2.01 2.52 0.97 29.50 1860__ 2.26 1.87 0.83 1.80 2.92 3.54 5.95 1.62 2.30 0.55 3.58 3.98 31.20 1861_ 1.17 2.39 3.25 4.51 2.81 3.55 3.70 2.57 4.96 3.42 1.17 1.55 35.05 1862_ 4.51 0.81 3.08 4.89 2.78 5.00 7.41 7.18 6.07 1.69 2.10 3.40 48.92 1863_ 2.84 3.05 2.56 2.39 3.41 0.45 2.78 2.38 2.37 4.30 0.94 2.77 29.24 1864_ 1.69 0.87 2.68 4.16 1.82 2.72 3.09 1.84 3.00 2.18 3.08 3.58 30.71 1865__ 0.85 3.41 3.13 5.00 2.01 3.66 5.76 5.57 7.27 2.21 0.31 0.65 39.83 1866_ 2.63 1.27 2.10 1.95 2.13 2.14 4.58 4.58 6.21 2.07 0.53 2.54 32.73 1867_ 1.27 2.70 1.70 1.85 5.60 3.00 2.50 2.77 1.43 0.98 2.01 1.21 27.02 1868_ 1.09 0.86 5.56 4.25 6.60 2.13 1.91 3.09 4.32 1.31 3.51 1.17 35.80 1869___ 1.44 2.22 1.23 2.82 5.70 7.11 6.55 6.00 1.07 1.17 4.20 2.46 41.97 1870_ 3.52 1.44 6.17 0.74 1.36 1.04 1.88 3.23 4.36 4.26 1.27 1.13 30.40 1871_ 3.05 2.02 2.64 2.67 2.60 4.42 2.42 3.96 0.58 3.03 2.78 2.80 32.97 1872_ 0.32 0.52 2.14 3.61 3.73 5.14 4.14 6.39 5.30 0.78 1.41 0.88 34.36 1873_ 3.39 0.69 1.04 4.96 5.24 1.86 3.55 1.46 2.17 1.96 1.24 4.53 32.09 1874_ 3.29 1.17 1.37 2.75 2.84 3.61 1.66 3.65 4.90 1.67 2.42 0.61 29.94 1875_ 0.50 1.52 1.36 2.29 3.38 4.67 8.11 1.78 5.42 2.51 0.64 2.79 34.97 1876_ 2.76 2.65 3.74 3.36 4.10 5.18 4.36 2.78 4.23 2.01 2.77 0.44 38.38 1877_ 1.21 0.06 3.48 3.08 2.46 7.21 3.17 2.24 1.65 5.62 3.90 2.80 36.88 1878_ 0.58 1.66 2.68 4.50 5.07 3.43 2.82 5.02 1.34 3.89 0.73 1.93 33.65 1879_ 0.76 1.07 1.82 2.14 2.88 3.66 3.75 2.28 1.83 2.15 4.31 1.64 28.29 1880_ 3.48 2.89 2.73 4.71 5.62 4.04 3.70 4.75 3.03 1.95 1.38 1.04 39.32 1881_ 0.96 5.12 3.43 1.56 2.44 7.77 3.64 0.82 4.41 .6.76 3.96 2.76 43.63 1882_ 1.28 2.00 3.34 4.55 5.19 7.80 3.82 3.80 1.35 3.64 1.83 1.99 40.59 1883_ 1.81 4.71 0.62 4.09 6.57 4.56 4.48 1.14 1.90 5.78 5.04 1.68 42.38 1884_ 0.96 2.66 2.98 2.63 3.25 3.17 5.43 3.28 3.74 5.19 1.97 3.97 39.20 1885_ 2.58 1.54 0.35 3.68 2.37 4.28 3.32 7.68 4.45 3.95 1.56 3.09 38.85 1886_ 3.00 1.73 3.02 3.01 4.58 2.36 0.94 2.89 4.56 1.99 1.17 1.11 30.36 1887_ 2.37 4.90 1.00 1.14 1.79 1.49 2.57 3.37 3.35 2.62 1.75 3.96 30.25 1888_ 1.70 1.51 2.98 1.63 6.59 2.56 3.82 2.94 1.39 2.73 2.95 2.28 33.08 1889_ 1.78 1.22 1.60 2.93 4.77 4.28 6.15 0.97 3.33 1.58 2.58 1.78 32.97 1890_ 2.90 1.56 2.68 2.54 4.24 5.86 0.97 2.27 1.97 4.08 1.68 0.73 31.48 1891_ 2.09 1.73 2.50 3.61 2.27 3.98 2.95 4.49 1.06 1.04 4.12 1.92 31.76 1892_ 1.70 1.38 2.58 4.24 9.45 9.38 3.63 1.66 2.16 0.93 2.17 2.04 41.32 1893_ 1.62 3.16 2.73 5.35 3.01 3.13 2.04 0.50 2.93 1.08 2.40 1.84 29.79 1894_ 1.98 1.52 2.77 1.95 3.24 2.76 0.59 1.66 6.22 1.45 1.64 1.08 26.86 1895___ 1.49 0.44 0.97 1.56 2.36 1.65 5.74 3.18 2.86 0.87 3.60 4.90 29.62 259 APPENDIX “A ” TABLE A-ll—Continued. PRECIPITATION FOR NORTHERN DISTRICT—AVERAGE OF ALL STATIONS—Concluded. Year. Jan. Feb. Mar. Apr. May. June. July. Aug. Sept. Oct. Nov. Dec. Total. 1896.. 1.05 1.64 1.13 3.72 5.00 2.93 3.03 3.17 5.86 0.85 2.13 0.30 30.81 1897__ 4.94 1.45 3.96 2.93 1.29 4.30 2.87 1.08 1.52 0.31 3.24 1.40 29.29 1898_ 3.76 2.16 5.25 2.70 5.48 4.37 1.28 5.52 4.56 3.50 2.15 1.10 41.83 1899_ 0.53 1.64 2.31 1.29 5.55 2.48 3.99 2.09 2.36 2.79 1.32 1.97 28.32 1900_ 1.56 3.51 2.62 1.44 4.18 1.85 4.09 5.90 3.17 2.45 2.55 0.37 33.69 1901_ 1.35 1.39 3.28 0.73 1.82 3.13 3.88 1.32 2.46 1.06 1.15 1.60 23.17 1902_ 0.56 1.44 3.33 2.26 5.37 10.11 8.49 4.76 5.35 2.71 2.85 2.02 49.25 1903_ 1.11 2.14 2.72 4.67 3.90 2.56 4.57 5.08 5.82 2.25 0.85 1.40 37.07 1904_ 2.26 1.24 4.04 2.97 3.21 1.91 5.08 4.33 4.57 0.69 0.09 1.84 32.23 1905_ 0.92 1.60 2.37 3.93 5.01 4.35 2.82 3.58 2.45 2.64 2.05 1.39 33.11 1906_ 2.49 2.16 2.72 1.94 3.08 3.26 2.80 3.44 5.01 1.70 2.72 2.13 33.45 1907_ 4.48 0.25 2.43 2.44 3.80 3.42 6.41 5.29 4.55 0.82 1.65 1.70 37.24 1908_ 0.99 3.25 3.15 3.33 7.80 2.84 3.33 3.50 1.19 0.86 2.44 0.97 33.65 1909_ 1.75 3.21 1.61 6.24 3.16 4.07 2.83 3.25 3.06 2.25 4.42 3.58 39.43 1910_ 2.05 0.97 0.33 3.44 4.89 1.41 1.66 3.18 3.85 1.29 0.70 1.11 24.88 1911_ 1.62 2.39 1.46 3.62 2.50 3.03 2.83 4.41 8.35 2.80 3.14 2.01 38.16 1912_ 0.53 1.21 1.81 3.64 4.02 2.43 3.23 3.10 2.90 4.45 1.80 0.91 30.03 1913_ 1.58 2.05 3.51 2.43 5.42 2.90 1.68 3.05 1.95 3.03 1.73 0.83 30.16 1914_ 1.59 0.88 2.35 1.51 3.94 3.86 1.06 2.31 4.40 2.50 0.33 1.90 26.63 1915_ 1.76 2.17 0.76 1.00 6.21 2.95 7.95 3.65 5.22 0.69 2.38 0.97 35.71 1916_ 5.14 0.52 2.41 1.59 4.62 6.20 0.72 2.45 3.00 4.13 1.95 1.89 34.62 1917_ 1.28 0.38 1.92 3.36 3.13 5.19 2.75 1.48 3.26 3.58 0.21 0.70 27.23 1918_ 2.40 1.93 0.99 3.17 4.93 3.08 3.32 3.41 2.14 3.25 2.01 2.30 32.93 1919_ 0.29 2.19 3.60 3.22 4.64 3.20 2.53 2.15 4.57 4.94 2.84 0.69 34.86 1920_ 1.02 0.26 5.02 5.07 2.80 2.62 1.42 1.86 1.78 1.81 1.26 2.32 27.24 1921_ 0.81 0.39 4.62 5.12 1.97 3.64 1.49 5.23 7.22 3.10 2.39 3.12 39.10 1922_ 1.19 1.16 4.01 3.04 4.39 0.65 4.44 1.27 2.82 1.52 2.68 1.10 28.27 1923_ 0.85 0.86 3.85 1.28 3.22 3.80 1.72 3.58 3.75 3.73 1.36 2.20 30.20 1924_ 1.45 1.49 2.66 2.00 2.04 7.81 3.28 7.83 3.02 0.77 0.93 2.00 35.28 1925___ 0.52 2.01 1.27 3.03 1.33 4.91 3.22 1.69 5.22 3.12 2.02 1.32 29.65 1926... 1.89 2.41 1.98 2.39 2.75 5.68 5.07 4.06 9.19 2.16 4.25 0.85 41.88 1927. 1.13 1.83 2.63 6.22 5.59 3.40 1.68 2.54 5.88 4.21 3.84 2.18 41.13 PRECIPITATION FOR CENTRAL DISTRICT—AVERAGE OF ALL STATIONS. Year. Jan. Feb. Mar. Apr. May. June. July. Aug. Sept. Oct. Nov. Dec. Total. Normal. 2.14 1.89 3.16 3.46 4.07 3.94 3.34 3.40 3.65 2.48 2.34 2.15 36.02 1856_ 1.30 4.69 0.90 2.18 2.47 3.20 3.58 3.15 3.62 3.50 3.39 3.95 35.93 1857_ 0.82 4.70 2.29 1.02 2.05 3.31 1.58 3.37 1.94 1.46 2.85 1.34 26.73 1858_ 2.07 1.66 2.37 4.32 7.30 5.57 6.60 1.96 2.95 3.70 3.16 2.57 44.23 1859 _ 1860 _ 2.64 3.22 4.27 3.49 9.29 6.14 1.96 4.12 3.28 1.51 2.36 1.19 43.47 1861_ 1.51 2.62 4.91 3.07 3.63 4.76 1.48 1.55 3.55 2.29 0.68 1.25 31.30 1862.__ 1863.. 4.89 2.85 0.68 4.01 2.23 2.99 6.87 2.00 2.31 4.34 0.58 5.34 3.18 1.70 2.22 6.15 3.11 1.62 3.52 2.20 1.19 4.93 4.68 42.95 1864_ 2.35 0.73 2.16 5.55 2.09 1.27 3.64 1.58 3.29 2.43 3.78 2.75 31.62 1865__ 0.25 4.02 4.30 5.77 0.69 6.77 9.58 1.69 5.81 3.34 0.12 1.44 43.78 1866_ 3.63 2.73 2.44 4.47 3.54 1.48 3.60 3.09 8.69 4.91 0.51 2.46 41.55 1867_ 1.73 4.44 1.82 1.24 5.22 3.51 3.27 2.18 1.14 1.21 1.47 1.16 28.39 1868_ 1.06 0.49 6.22 5.48 6.31 2.64 3.56 3.69 4.09 1.59 4.07 2.41 41.61 1869_ 2.92 2.27 1.69 5.37 4.78 6.48 7.38 4.22 1.38 1.93 3.16 2.47 44.05 1870.. 2.04 0.47 4.40 1.50 1.69 2.33 3.12 4.74 3.00 3.67 1.85 1.90 30.71 1871_ 4.22 1.60 3.89 2.02 2.11 2.90 2.83 2.62 0.63 3.57 2.43 1.90 30.72 1872_ 0.51 1.41 2.87 2.62 2.79 7.61 5.68 2.20 2.92 0.56 1.15 1.30 31.62 1873_ 4.13 1.75 0.96 6.18 4.59 1.71 5.22 0.94 4.05 3.30 2.05 5.33 40.21 1874... 2.94 1.77 1.67 2.89 2.21 3.81 3.34 5.25 3.92 1.39 2.53 1.09 32.81 1875_ 0.43 2.13 2.88 1.70 5.84 6.25 11.77 2.14 5.70 2.62 0.64 3.30 45.40 260 FLOOD CONTROL REPORT TABLE NO. A-ll—Concluded. PRECIPITATION FOR CENTRAL DISTRICT—AVERAGE OF ALL SATTIONS—Concluded. Year. Jan. Feb. Mar. Apr. May. June. July. Aug. Sept. Oct. Nov. Dec. Total. 1876. 2.13 1.48 4.57 3.68 4.70 5.46 7.12 5.02 9.58 2.02 2.27 0.21 48.24 1877__ 0.82 0.13 4.59 3.27 4.05 7.97 5.16 2.84 3.03 7.76 3.55 3.78 46.95 1878.. 0.86 3.27 3.96 2.79 4.19 3.41 3.11 5.67 1.25 2.58 1.55 2.89 35.53 1879__ 0.62 0.66 1.81 1.41 1.95 2.83 2.22 4.53 1.34 0.57 4.33 1.95 24.12 1880.. 3.88 3.32 3.09 4.94 6.01 2.73 2.11 3.08 2.78 1.89 1.74 1.49 37.06 1881... 0.93 4.73 3.59 2.36 1.86 6.47 2.52 1.92 4.83 8.44 5.91 3.34 46.93 1882. 1.94 4.76 4.21 3.72 7.50 9.31 2.81 3.64 1.22 3.25 2.45 2.16 46.97 1883_ 1.31 6.70 1.28 3.46 4.52 5.54 4.14 1.44 0.89 7.18 3.56 1.78 41.80 1884.. 1.34 3.67 3.02 2.56 3.81 4.97 3.04 2.23 5.59 2.99 1.76 4.62 39.60 1885... 2.90 1.21 0.30 4.97 3.15 6.34 2.86 4.22 5.08 4.36 1.52 2.40 39.31 1886___ 2.70 1.51 2.64 2.34 3.96 4.71 1.22 4.13 6.02 0.78 2.32 1.22 33.55 1887.. 1.18 4.31 2.36 2.91 4.00 1.44 1.66 2.60 3.64 0.94 3.99 3.97 33.00 1888__ 2.60 2.17 3.41 2.09 6.35 5.79 5.26 3.18 1.95 2.83 4.22 2.61 42.45 1889.. 1.89 1.78 1.43 1.37 5.60 5.70 3.90 0.85 4.06 2.64 3.58 1.63 34.43 1890.. 4.91 2.32 2.34 2.72 3.38 4.38 2.99 2.46 2.85 1.77 1.96 0.47 32.55 1891. 1.42 2.69 3.19 3.38 1.90 3.28 2.33 5.16 0.81 1.38 4.89 1.33 31.76 1892... 1.62 3.00 2.07 7.43 8.15 4.06 4.29 2.27 2.43 0.99 4.04 1.55 41.90 1893_ 0.89 3.45 3.61 7.43 4.94 2.55 2.01 0.63 2.86 0.67 1.99 1.39 32.42 1894__ 2.30 2.27 2.85 2.71 2.58 2.35 1.71 1.64 4.13 0.88 2.18 2.07 27.67 1895. 1.30 0.72 1.40 2.47 1.74 2.88 5.20 2.62 3.43 0.46 3.45 5.79 31.46 1896.. 1.08 2.00 1.65 2.19 5.05 4.39 7.36 3.43 5.89 1.10 2.23 0.59 36.96 1897.. 5.02 1.53 4.89 4.42 2.36 4.97 3.80 1.18 0.61 0.32 4.42 2.54 36.06 1898_ 4.49 2.01 7.45 3.29 6.50 3.79 2.63 3.63 5.62 4.19 2.46 1.49 47.55 1899... 1.53 2.10 3.14 1.42 7.86 2.43 2.79 3.37 2.39 3.54 2.13 2.21 34.91 1900.. 1.05 4.83 1.64 1.37 3.84 3.57 4.22 3.94 3.90 2.89 2.63 0.73 34.61 1901.. 1.71 1.52 3.29 1.76 1.86 4.80 1.79 1.68 1.53 2.18 1.28 3.03 26.43 1902.. 0.96 1.31 3.65 2.69 2.92 9.36 3.71 5.58 3.76 2.41 2.90 3.02 42.27 1903. 1.39 2.99 2.29 4.72 3.10 3.12 3.15 4.26 3.43 2.40 1.06 1.72 33.63 1904. 3.18 1.15 6.31 4.41 3.62 3.33 4.69 3.85 5.19 0.52 0.25 1.38 37.88 1905. 1.76 1.54 1.66 3.55 3.87 2.97 4.68 3.14 3.53 4.30 2.20 1.84 35.04 1906... 2.84 2.04 3.88 2.43 2.91 2.96 2.25 3.99 4.35 1.32 3.55 2.90 35.42 1907. 5.90 0.32 3.55 2.78 3.43 4.77 6.39 5.51 1.55 1.51 1.93 2.58 40.22 1908. 1.36 4.24 2.53 4.65 8.86 3.17 2.89 1.70 1.50 0.54 2.60 1.32 35.36 1909... 2.12 4.07 1.75 5.99 4.79 4.39 6.00 1.56 3.69 3.25 3.97 2.31 43.89 1910... 1.90 1.69 0.31 3.15 6.04 2.57 4.10 2.22 4.72 2.34 1.58 1.27 31.89 1911.. 2.43 2.03 2.05 4.34 1.62 2.14 2.88 3.27 10.50 2.82 2.67 2.01 38.76 1912. 0.90 1.55 3.74 5.48 4.66 2.96 3.73 3.76 2.20 3.06 2.00 0.70 34.74 1913... 3.97 1.56 5.45 3.03 1.71 2.80 1.19 1.90 3.21 3.41 3.44 0.95 32.62 1914.. 1.78 2.33 1.32 2.49 1.63 1.98 1.83 3.28 3.73 2.62 0.72 2.12 25.83 1915. 2.13 2.09 0.84 2.11 7.08 5.58 7.04 6.12 4.85 0.79 2.11 2.68 43.42 1916.... 6.78 0.85 1.78 1.55 5.63 4.37 0.96 4.20 2.70 2.29 1.96 1.85 34.92 1917. 1.39 0.48 3.44 4.48 4.77 6.93 2.65 3.11 2.75 2.47 0.29 0.73 33.49 1918... 1.80 1.62 0.86 5.66 4.82 4.26 2.50 3.77 4.38 3.23 2.41 3.22 38.53 1919.. 0.32 1.93 2.93 1.65 5.10 5.45 1.78 3.18 3.62 5.79 3.14 0.37 35.26 1920. 0.96 0.66 4.70 4.72 5.10 2.11 2.74 2.6? 3.19 2.13 0.95 2.47 32.42 1921... 1.70 0.57 5.11 4.84 2.05 3.87 2.22 5.12 6.68 2.38 3.21 2.44 40.19 1922. 1.42 1.29 6.82 6.29 3.42 1.54 3.55 1.88 1.70 1.98 3.30 2.01 35.20 1923.. 1.38 1.04 4.54 2.25 4.24 3.30 2.37 4.75 4.56 3.88 1.68 3.63 37.62 1924. 1.76 1.64 2.74 2.13 3.64 6.80 3.05 4.75 3.15 1.54 1.27 4.49 36.96 1925... 0.49 1.47 3.00 2.47 1.24 4.60 3.20 3.86 4.16 3.46 2.90 1.36 32.21 1926. 1.63 2.44 2.67 3.50 2.45 4.72 3.18 4.40 12.07 4.37 3.53 1.35 46.31 1927... 1.89 1.45 5.06 6.60 7.52 4.08 3.76 3.64 4.82 4.20 4.81 2.93 50.76 261 APPENDIX “A.” TABLE NO. A-12—RAINFALL AND RIVER STAGE RELATION BY INDIVIDUAL STORM PERIODS. IROQUOIS RIVER AT CHEBANSE—1926-1927. Stages and dates. Rise. Rainfall. Rise per inch of rainfall, feet. Aver¬ age rise per day, feet. From. To Amount, feet. Dura¬ tion, days. Amount, inches. Dura¬ tion, days. Great¬ est 1-day. Great¬ est 2-day. Stage. Date. Stage. Date. 1.8 Aug. 11 4.9 Aug. 16 3.1 5 1.92 4 0.56 1.04 1.61 0.62 3.4 Aug. 19 6.0 Aug. 24 2.6 5 1.14 1 1.14 1.28 0.52 2.7 Sept. 1 8.9 Sept. 5 6.2 4 3.65 4 1.33 1.76 1.70 1.55 5.2 Sept. 22 11.7 Sept. 28 6.5 6 3.20 3 1.65 2.13 2.03 1.08 11.1 Oct. 1 16.2 Oct. 5 5.1 4 2.77 4 0.99 1.73 1.84 1.27 3.6 Nov. 11 7.7 Nov. 17 4.1 6 1.91 5 0.78 0.93 2.15 0.68 2.6 Jan. 25 12.2 Feb. 3 9.6 9 1.55 t 1.07 1.20 6.19 1.07 10.3 Feb. 4 12.2 Feb. 6 1.9 2 1.37 2 0.90 1.37 1.39 0.95 3.4 Mar. 6 4.9 Mar. 12 1.5 6 0.40 2 0.23 0.37 3.75 0.25 4.9 Mar. 12 5.9 Mar. 14 1.0 2 0.47 2 0.26 0.46 2.13 0.50 5.0 Mar. 17 12.6 Mar. 21 7.6 4 2.46 2 1.65 0.81 3.09 1.90 4.4 Apr. 1 8.6 Apr. 3 4.2 2 0.61 1 0.61 6.89 2.10 6.2 Apr. 14 11.4 Apr. 18 5.2 4 2.35 6 0.74 1.43 2.21 1.30 5.5 Apr. 27 7.2 Apr. 30 1.7 3 1.18 1 1.12 1.18 1.44 0.57 1.8 May 18 13.5 May 22 11.7 4 2.60 2 1.96 2.60 4.50 2.92 1.4 June 19 4.4 June 22 3.0 3 1.74 1 1.57 1.74 1.72 1.00 t Snow. ILLINOIS RIVER AT MORRIS—1926-1927. 7.1 Aug. 21 8.2 Aug. 24 1.1 3 0.66 2 0.51 0.66 1.67 0.37 6.7 Sept. 1 11.0 Sept. 6 4.3 5 2.12 5 0.76 1.05 2.03 0.86 7.7 Sept. 23 14.0 Sept. 26 6.3 3 2.59 3 1.63 2.15 2.43 2.10 13.0 Sept. 30 16.2 Oct. 5 3.2 5 1.85 4 0.58 1.08 1.73 0.64 7.2 Nov. 8 8.0 Nov. 10 0.8 2 0.63 1 0.51 0.63 1.27 0.40 7.5 Nov. 13 14.9 Nov. 16 7.4 3 1.74 3 0.61 1.18 4.25 2.47 6.5 Jan. 29 20.0 Feb. 6 13.5 8 2.28 t 0.92 1.08 5.92 1.69 8.1 Mar. 6 9.5 Mar. 9 1.4 3 0.28 1 0.19 0.28 5.00 0.47 9.5 Mar. 19 13.8 Mar. 23 4.3 4 0.95 2 0.70 0.95 4.53 1.07 9.1 Apr. 1 11.9 Apr. 5 2.8 4 0.75 2 0.64 0.75 3.73 0.70 10.2 Apr. 14 14.2 Apr. 17 4.0 3 1.70 4 0.87 1.02 2.35 1.33 14.0 Apr. 18 19.2 Apr. 20 5.2 2 1.41 2 0.86 1.41 3.69 2.60 10.5 Apr. 28 14.3 Apr. 30 3.8 2 1.04 1 1.04 3.65 1.90 7.4 May 18 13.8 May 21 6.4 3 1.63 2 1.10 1.63 3.92 2.13 13.8 May 21 16.9 May 25 3.1 4 1.84 3 1.02 1.44 1.68 1.03 9.5 June 3 16.9 June 5 7.4 2 1.82 3 1.32 1.58 4.06 3.70 t Snow. ILLINOIS RIVER AT LA SALLE—1926-1927. 7.3 Sept. 1 12.7 Sept. 7 5.4 6 2.30 4 0.85 1.17 2.34 0.90 12.1 Sept. 14 13.6 Sept. 16 1.5 2 0.91 2 0.65 0.91 1.65 0.75 12.2 Sept. 23 17.3 Sept. 25 5.1 2 2.65 3 1.68 2.29 1.93 2.55 16.7 Oct. 1 20.0 Oct. 7 3.3 6 1.81 4 0.65 1.14 1.82 0.55 9.9 Nov. 13 16.9 Nov. 17 7.0 4 1.94 3 0.73 1.46 3.61 1.75 8.6 Jan. 30 19.5 Feb. 7 10.9 8 2.40 f2 0.94 1.09 4.54 1.36 11.6 Mar. 11 13.7 Mar. 15 2.1 4 0.43 1 0.36 0.43 4.89 0.52 12.6 Mar. 20 15.0 Mar. 25 2.4 5 0.91 1 0.74 0.91 2.64 0.48 12.8 Apr. 1 14.5 Apr. 6 1.7 5 0.69 1 0.69 0.78 2.46 0.34 13.3 Apr. 15 20.1 Apr. 21 6.8 6 3.00 7 0.88 1.39 2.26 1.13 16.6 Apr. 28 17.5 May 1 0.9 3 1.08 1 1.00 1.08 0.83 0.30 12.0 May 18 16.0 May 22 4.0 4 1.60 2 1.16 1.60 2.50 1.00 16.0 May 22 19.6 May 26 3.6 4 1.73 3 0.94 1.43 2.08 0.90 15.7 June 3 18.8 June 5 3.1 2 1.39 2 1.14 1.39 2.23 1.55 t Snow. 262 FLOOD CONTROL REPORT. TABLE NO. A-12—Concluded. ILLINOIS RIVER AT PEORIA—1926-1927. Stages and dates. Rise Rainfall. Rise Aver¬ age rise per day, feet. F Stage. rom. Date Stage. To. Date Amount, feet. Dura¬ tion, days. Amount, inches. Dura¬ tion, days. Great¬ est 1-day. Great¬ est 2-day. per inch of rainfall, feet. 12.3 Aug. 31 17.7 Sept. 10 5.4 10 2.75 5 1.03 1.32 1.97 0.54 17.7 Sept. 14 19.0 Sept. 19 1.3 5 1.00 2 0.68 0.32 1.30 0.67 19.0 Sept. 23 20.8 Sept. 27 1.8 4 2.60 3 1.63 2.28 0.69 0.45 20.8 Sept. 27 25.0 Oct. 9 4.2 12 1.79 4 0.62 1.08 2.34 0.35 15.0 Nov. 13 21.2 Nov. 21 6.2 7 2.09 3 0.86 1.58 2.96 0.89 13.9 Jan. 31 22.6 Feb. 10 8.7 10 1.90 2 0.96 1.12 4.58 0.87 16.5 Mar. 10 18.4 Mar. 20 1.9 10 0.54 1 0.42 0.54 3.52 0.19 18.1 Mar. 21 19.8 Mar. 27 1.7 6 0.93 1 0.75 0.93 1.83 0.28 19.2 Apr. 17 24.7 Apr. 24 5.5 7 2.94 7 0.82 0.95 1.87 0.78 18.3 May 17 21.3 May 23 3.0 6 1.67 2 1.27 0.40 1.80 0.50 21.3 May 23 24.0 May 29 2.7 6 1.69 3 0.93 1.43 1.60 0.45 22.2 June 3 23.8 June 7 1.6 4 1.45 1 1.18 1.45 1.10 0.40 ILLINOIS RIVER AT HAVANA—1926-1927. 10.0 Aug. 30 15.5 Sept. 6 5.5 7 3.59 5 1.43 1.68 1.53 0.79 15.5 Sept. 6 17.8 Sept. 13 2.3 7 1.31 4 0.43 0.80 1.76 0.33 17.8 Sept. 13 19.2 Sept. 18 1.4 5 1.12 2 0.75 1.07 1.25 0.28 17.6 Sept. 24 18.4 Sept. 27 0.8 3 2.47 3 1.44 2.01 0.32 0.27 18.4 Sept. 28 22.7 Oct. 9 4.3 11 2.36 6 0.63 1.16 1.82 0.39 13.4 Nov. 13 17.5 Nov. 22 4.5 9 2.79 6 0.98 1.76 1.56 0.50 17.5 Nov. 22 18.4 Nov. 30 0.9 8 0.21 1 0.18 0.21 4.28 0.11 11.8 Jan. 31 18.1 Feb. 14 6.3 14 1.82 t2 0.85 1.11 3.46 0.45 14.0 Mar. 11 15.0 Mar. 15 1.0 4 0.75 2 0.42 0.70 1.33 0.25 15.1 Mar. 19 17.6 Mar. 28 2.5 9 1.00 2 0.77 1.00 2.50 0.28 17.5 Apr. 1 18.0 Apr. 10 0.5 9 1.36 4 0.79 0.91 0.37 0.06 18.1 Apr. 15 22.0 Apr. 28 3.9 13 2.96 7 0.79 0.93 1.32 0.30 22.0 Apr. 28 21.2 May 1 0.8 3 0.98 1 0.93 0.98 ♦ 0.27 16.9 May 17 19.0 May 21 2.1 4 2.08 2 1.74 2.08 1.01 0.53 19.1 May 23 21.3 May 29 2.2 6 1.89 4 0.93 1.49 1.16 0.37 21.1 June 4 21.8 June 7 0.7 3 1.84 3 1.09 1.43 0.38 0.23 t Snow. * Fall. ILLINOIS RIVER AT BEARDSTOWN—1926-1927. 10.0 Aug. 31 16.5 Sept. 7 6.5 7 3.79 5 1.27 2.09 1.71 0.93 16.5 Sept. 7 19.9 Sept. 12 3.4 5 1.49 2 0.75 1.49 2.28 0.68 19.9 Sept. 12 22.1 Sept. 17 2.2 5 1.06 2 0.70 0.98 2.08 0.44 20.4 Sept. 27 25.5 Oct. 6 5.1 9 5.74 12 1.25 1.67 0.69 0.57 25.2 Oct. 7 26.2 Oct. 11 1.0 4 0.25 2 0.14 0.17 4.00 0.50 14.5 Nov. 13 19.4 Nov. 24 4.9 11 2.91 5 0.96 1.79 1.68 0.45 19.4 Nov. 24 20.4 Nov. 30 1.0 6 0.25 tl 0.22 0.25 4.00 0.17 11.9 Feb. 1 19.8 Feb. 14 7.9 13 2.19 2 0.70 0.93 3.61 0.61 15.6 Mar. 11 17.0 Mar. 16 1.4 5 0.71 2 0.36 0.66 1.97 0.27 12.0 Mar. 18 20.5 Mar. 28 3.5 10 1.46 3 0.80 1.23 2.40 1.17 20.1 Apr. 1 20.9 Apr. 4 0.8 3 1.02 1 0.91 1.02 0.78 0.27 21.0 Apr. 11 22.0 Apr. 18 1.0 7 2.41 7 0.66 1.10 0.42 0.14 22.0 Apr. 18 25.2 Apr. 26 3.2 8 1.13 3 0.78 0.92 2.83 0.40 19.4 May 18 20.5 May 21 1.1 3 1.97 2 1.60 1.97 0.55 0.37 20.5 May 21 24.7 May 29 4.2 8 2.27 6 0.93 1.51 1.85 0.53 ' 24.2 June 4 24.9 June 6 0.7 2 1.66 2 0.90 1.24 0.42 0.35 t Snow 263 APPENDIX “A.” TABLE NO. A-13—RAINFALL AND RIVER STAGE RELATION BY INDIVIDUAL STORM PERIODS. ILLINOIS RIVER AT MORRIS—1921-1922. Stages and dates. Rise. • Rainfall. Rise Aver- per age From. To. Dura- Dura- Great- Great- inch rise Amount, tion, Amount, tion, est est day, feet. days. inches. days. 1-day. 2-day. feet. feet. Stage. Date. Stage. Date. 7.6 Nov. 18 11.8 Nov. 20 4.2 2 2.11 2 1.23 2.11 1.99 2.20 9.1 Dec. 1 11.5 Dec. 3 2.4 2 0.80 2 0.50 0.80 3.00 1.20 8.6 Dec. 15 12.4 Dec. 18 3.8 3 1.34 3 0.61 1.16 2.84 1.26 8.1 Jan. 3 10.3 Jan. 4 2.2 1 0.91 1 0.91 2.42 2.20 7.0 Jan. 23 10.6 Jan. 25 3.6 2 * 7.0 Feb. 21 9.3 Feb. 25 2.3 4 0.44 4 0.23 0.29 5.23 0.57 7.7 Mar. 10 10.1 Mar. 13 2.4 3 0.66 2 0.41 0.66 3.64 0.80 10.0 Mar. 13 11.6 Mar. 16 1.6 3 0.53 1 0.53 3.02 1.60 11.4 Mar. 19 13.8 Mar. 21 2.4 2 0.96 2 0.71 0.96 2.50 1.20 12.1 Mar. » 30 17.4 Apr. 2 5.3 3 1.71 2 0.91 1.71 3.10 1.76 13.0 Apr. 10 20.3 Apr. 12 7.3 2 2.10 2 1.38 2.10 3.48 3.65 * Only .05 in. rainfall increase from 6400 c.f.s. to 7300 c.f.s. in Chicago Sanitary District discharges. ILLINOIS RIVER AT LA SALLE—1921-1922. 7.5 Nov. 18 12.2 Nov. 23 4.7 5 2.06 3 1.05 1.80 2.28 0.94 11.5 Dec. 2 12.8 Dec. 4 1.3 2 0.94 2 0.55 0.94 1.38 0.65 10.7 Dec. 16 13.3 Dec. 19 2.6 3 1.35 3 0.64 1.21 1.93 0.87 11.0 Jan. 2 13.4 Jan. 7 2.4 5 0.93 2 0.88 0.93 2.73 0.42 10.4 Jan. 13 12.5 Jan. 15 2.1 2 ♦ 7.4 Feb. 13 9.8 Feb. 15 2.4 2 ♦ 6.8 Feb. 21 9.2 Feb. 25 2.4 4 0.54 4 0.25 0.43 t 8.4 Mar. 10 10.2 Mar. 12 1.8 2 0.59 2 0.40 0.59 3.05 0.90 10.7 Mar. 14 12.0 Mar. 16 1.3 2 0.45 1 0.45 2.89 0.65 12.7 Mar. 20 13.7 Mar. 21 1.0 1 0.91 3 0.71 0.85 1.10 1.00 13.2 Mar. 26 17.8 Apr. 3 4.6 8 2.47 7 0.81 1.48 1.86 0.57 17.2 Apr. 10 20.0 Apr. 14 2.8 4 1.86 3 1.25 1.78 1.50 0.70 * No rain. (Sanitary District inflow?) t Probably some Chicago Sanitary District water. ILLINOIS RIVER AT PEORIA—1921-1922. 12.3 Nov. 17 16.1 Nov. 28 3.8 11 1.72 2 1.00 1.72 2.21 0.35 16.1 Nov. 30 17.4 Dec. 7 1.3 7 1.04 2 0.61 1.04 1.25 0.19 16.2 Dec. 16 17.4 Dec. 21 1.2 5 1.18 2 0.62 1.18 1.02 0.24 15.2 Jan. 3 16.3 Jan. 10 1.0 7 1.00 *1 0.89 0.93 1.00 0.14 12.5 Feb. 22 14.0 Feb. 28 1.5 6 0.52 2 0.25 0.34 2.88 0.25 14.1 Mar. 12 15.0 Mar. 15 0.9 3 0.60 2 0.42 0.60 1.50 0.30 15.0 Mar. 15 16.0 Mar. 18 1.0 3 0.43 1 0.43 2.32 0.33 16.0 Mar. 18 17.5 Mar. 23 1.5 5 0.88 2 0.72 0.84 1.71 0.30 17.5 Mar. 24 18.6 Mar. 29 1.1 5 0.99 4 0.28 0.45 1.11 0.22 18.6 Mar. 29 23.2 Apr. 8 4.6 10 1.43 2 0.80 1.43 3.22 0.46 22.9 Apr. 11 24.8 Apr. 15 1.9 4 1.67 2 1.11 1.67 1.14 0.48 * Thaw. ILLINOIS RIVER AT BEARDSTOWN—1921-1922. 9.0 Nov. 18 14.0 Dec. 5 5.0 17 3.04 17 0.98 1.84 1.65 0.29 11.2 Mar. 12 13.0 Mar. 15 1.8 3 1.04 2 1.02 1.04 1.74 0.60 14.8 Mar. 19 16.2 Mar. 21 1.4 2 0.91 2 0.79 0.91 1.54 0.70 18.8 Mar. 31 19.9 Apr. 4 1.1 4 1.54 2 0.80 1.54 0.68 0.27 22.4 Apr. 11 24.7 Apr. 16 2.3 5 1.99 5 0.89 1.49 1.15 0.46 264 FLOOD CONTROL REPORT TABLE NO. A-13—Concluded. ILLINOIS RIVER AT HAVANA—1921-1922. Stages and dates. Rise. Rainfall. Rise Aver- F Stage. rom. Date. Stage. To. Date. Amount, feet. Dura¬ tion, days. Amount, inches. Dura¬ tion, days. Great¬ est 1-day. Great¬ est 2-day. per inch of rainfall, feet. age rise per day, feet. 9.4 Nov. 16 14.0 Dec. 7 4.6 21 3.19 17 0.87 1.05 1.44 0.22 11.4 Mar. 11 16.1 Mar. 82 4.7 17 2.96 19 0.68 0.81 1.58 0.27 16.5 Mar. 30 17.5 Apr. 3 1.0 4 1.41 2 0.77 1.41 1.41 0.25 19.9 Apr. 11 22.2 Apr. 17 2.3 6 2.07 7 0.95 1.50 1.11 0 38 TABLE NO. A-14—RAINFALL AND RIVER STAGE RELATION BY INDIVIDUAL STORM PERIODS. ILLINOIS RIVER AT MORRIS—1915-1916. Stages and dates. Rise. Rainfall. Rise Aver*- From. To. Amount, Dura¬ tion, days. Amount, inches. Dura¬ tion, days. Great¬ est 1-day. Great¬ est 2-day. per inch of rainfall, feet. age rise per day, feet. Stage. Date Stage. Date feet. 5.6 Jan. 1 11.1 Jan. 5 5.5 4 1.60 tl 0.76 0.79 3.44 1.37 8.8 Jan. 16 22.9 Jan. 22 14.1 6 2.42 t 0.89 1.04 5.83 2.35 12.3 9.1 Jan. 30 Feb. 8 14.9 12.9 Feb. 1 Feb. 11 2.6 3.8 2 3 0.97 0.19 2 0.56 0.09 0.77 0.14 2.68 1.30 f Thaw. ILLINOIS RIVER AT LA SALLE—1915-1916. 5.9 Dec. 18 8.0 Dec. 23 2.1 5 0.67 t 0.35 0.48 3.12 0.42 6.1 Dec. 27 8.5 Dec. 29 2.4 2 0.47 t 0.22 0.47 5.11 1.20 6.0 Jan. 1 10.8 Jan. 6 4.8 5 0.84 1 0.79 0.84 5.71 0.96 9.1 Jan. 12 13.7 Jan. 16 4.6 4 1.04 2 0.86 0.98 4.42 1.15 9.8 Jan. 19 23.1 Jan. 23 *13.3 4 1.39 t2 0.93 1.07 9.56 *3.33 * Probably due to Chicago Sanitary District water, t Thaw. ILLINOIS RIVER AT PEORIA—1915-1916. 10.7 Jan. 1 14.3 Jan. 10 3.6 9 1.37 *2 0.79 0.84 2.63 0.40 15.3 Jan. 20 23.2 Jan. 25 7.9 5 2.51 *2 1.01 1.14 3.15 1.58 * Snow. ILLINOIS RIVER AT HAVANA—1915-1916. 8.9 Jan. 1 10.7 Jan. 5 1.8 4 1.31 *1 0.87 0.91 1.38 0.45 12.6 Jan. 21 18.2 Jan. 26 5.6 5 2.66 *3 1.02 1.21 2.10 1.12 18.2 Jan. 26 19.5 Jan. 31 1.3 5 1.31 4 0.42 0.80 0.99 0.26 * Snow. ILLINOIS RIVER AT BEARDSTOWN—1915-1916. 9.4 Jan. 1 11.8 Jan. 5 2.4 4 1.44 *2 0.85 0.88 1.67 0.60 12.5 Jan. 20 18.2 Jan. 26 5.7 6 2.71 * 1.04 1.32 2.10 0.95 18.2 Jan. 26 20.5 Jan. 31 2.3 5 1.61 4 0.59 1.00 1.43 0.46 * Snow. 265 APPENDIX “A ” TABLE NO. A-15—RAINFALL AND RIVER STAGE RELATION BY INDIVIDUAL STORM PERIODS. ILLINOIS RIVER AT MORRIS—1913. Stages and dates. Rise. Rainfall. Rise per inch of rainfall, feet. Aver¬ age rise per day, feet. From To. Amount, feet. Dura¬ tion, days. Amount, inches. Dura¬ tion, days. Great¬ est 1-day. Great¬ est 2-day. Stage. Date. Stage. Date. 10.7 Apr. 9 13.8 Apr. 11 3.1 2 1.26 2 0.79 1.01 2.46 1.55 Note. —No gauge readings to March 24, 1913, from January 1, 1913. ILLINOIS RIVER AT LA SALLE—1913. 4.5 Jan. 5 9.0 Jan. 8 4.5 3 0.83 3 0.41 0.70 5.42 1.50 7.3 Jan. 20 11.7 Jan. 26 4.4 6 1.04 * 0.48 0.51 4.23 0.73 9.2 Feb. 21 12.7 Feb. 23 3.5 2 0.71 2 0.47 0.71 4.93 1.75 9.7 Mar. 8 13.2 Mar. 10 3.5 2 11.8 Mar. 13 12.9 Mar. 15 1.1 2 0.37 1 0.28 0.37 2.97 0.55 11.2 Mar. 21 12.3 Mar. 22 1.1 1 0.78 2 0.67 0.78 1.41 1.10 12.3 Mar. 23 19.3 Mar. 29 7.0 6 2.57 4 1.07 1.75 2.72 1.17 15.4 Apr. 9 16.7 Apr. 12 1.3 3 1.29 3 0.73 1.05 1.01 0.43 * Thaw. Note. —Did not have temperatures for 1913. ILLINOIS RIVER AT PEORIA—1913. 10.8 Jan. 17 12.0 Jan. 21 1.2 4 0.63 3 0.44 0.47 1.91 0.30 12.0 Jan. 22 15.0 Jan. 28 3.0 6 0.96 *1 0.45 0.46 3.12 0.50 12.9 Feb. 21 14.3 Feb. 25 1.4 4 0.85 2 0.62 0.85 1.65 0.35 13.3 Mar. 9 16.6 Mar. 17 3.3 8 1.35 *2 0.26 0.37 2.45 0.41 16.6 Mar. 23 22.3 Mar. 30 5.7 7 3.07 5 1.07 1.70 1.85 0.82 21.0 Apr. 11 21.5 Apr. 13 0.5 2 1.04 2 0.73 1.04 0.48 0.25 * Thaw. ILLINOIS RIVER AT HAVANA—1913. 9.7 Jan. 23 12.3 Feb. 1 2.6 8 1.24 * 0.47 0.49 2.10 0.33 11.2 Feb. 20 12.8 Feb. 24 1.6 4 0.98 2 0.79 0.98 1.63 0.40 11.3 Mar. 8 13.6 Mar. 18 2.3 10 12.3 Mar. 22 19.9 Apr. 3 7.6 12 3.15 5 1.06 1.65 2.38 0.63 * Thaw. ILLINOIS RIVER AT BEARDSTOWN—1913. 11.3 Feb. 21 12.8 Feb. 28 1.5 7 0.84 2 0.69 0.84 1.79 0.21 11.6 Mar. 9 13.2 Mar. 20 1.6 11 * 13.2 Mar. 20 21.9 Apr. 5 8.7 16 3.71 7 1.13 1.82 2.35 0.54 * Thaw. Note. —No gauge readings to February 1, 1913 266 FLOOD CONTROL REPORT. TABLE NO. A-16—RAINFALL AND RIVER STAGE RELATION BY INDIVIDUAL STORM PERIODS. ILLINOIS RIVER AT MORRIS—1904. Stages and dates. Rise. Rainfall. Rise per inch of rainfall, feet. Aver¬ age rise per day, feet. From. To Amount, feet. Dura¬ tion, days. Amount, inches. Dura¬ tion, days. Great¬ est 1-day. Great¬ est 2-day. Stage. Date. Stage. Date. 5.7 Jan. 20 14.0 Jan. 22 8.3 2 2.29 * 1.12 1.59 3.62 4.15 8.0 Feb. 6 13.6 Feb. 8 5.6 2 0.91 * 0.20 0.21 6.15 2.80 7.0 Feb. 28 16.7 Mar. 4 9.7 5 1.72 * 0.47 0.54 5.54 1.94 14.2 Mar. 6 15.5 Mar. 8 1.3 2 0.37 1 0.34 0.37 3.51 0.65 8.8 Mar. 18 15.0 Mar. 20 6.2 2 1.19 3 0.58 0.66 5.21 3.10 15.0 Mar. 22 16.9 Mar. 23 1.9 1 0.78 2 0.41 0.78 2.44 1.90 17.0 Mar. 24 20.2 Mar. 26 3.2 2 1.25 2 0.85 1.25 2.56 1.60 14.8 Mar. 31 16.8 Apr. 2 2.0 2 1.19 3 0.51 0.96 1.68 1.00 6.4 Apr. 23 11.6 Apr. 28 5.2 5 2.18 5 0.80 1.31 2.38 1.04 * Thaw. ILLINOIS RIVER AT LA SALLE—1904. 13.6 Jan. 19 23.2 Jan. 23 9.6 4 1.81 *2 1.00 1.49 5.31 2.40 17.7 Feb. 5 22.7 Feb. 9 5.0 4 0.71 * 0.15 0.23 7.05 1.25 16.8 Feb. 28 24.8 Mar. 4 8.0 5 1.50 * 0.47 0.51 5.33 1.60 23.8 Mar. 7 25.7 Mar. 9 1.9 2 0.40 1 0.30 0.34 4.75 0.95 21.8 Mar. 19 27.1 Mar. 23 5.3 4 1.46 6 0.60 0.76 3.63 1.32 26.8 Mar. 24 29.3 Mar. 27 2.5 3 1.03 2 0.84 1.03 2.43 0.83 18.8 Apr. 23 20.9 Apr. 28 2.1 5 1.98 5 0.65 1.27 1.06 0.42 * Thaw. ILLINOIS RIVER AT PEORIA—1904. 10.0 Jan. 20 16.2 Jan. 28 6.2 8 1.91 *2 1.04 1.51 3.24 0.76 15.2 Feb. 6 16.6 Feb. 11 1.4 5 0.57 *1 0.11 0.12 2.46 0.28 13.5 Feb. 28 18.5 Mar. 11 5.0 12 2.11 *1 0.27 0.33 2.37 0.42 17.1 Mar. 19 18.2 Mar. 21 1.1 2 0.64 1 0.58 0.64 1.72 0.56 18.2 Mar. 21 23.0 Mar. 28 4.8 7 1.91 5 0.77 1.06 2.51 0.69 15.4 Apr. 24 16.2 Apr. 29 0.8 5 1.55 3 0.65 1.25 0.52 0.16 * Thaw. ILLINOIS RIVER AT HAVANA—1904. JL 8.6 Jan. 20 14.3 Jan. 27 5.7 7 2.17 *2 1.09 1.56 2.62 0.82 13.0 Feb. 29 15.5 Mar. 14 2.5 14 1.31 * 0.41 0.49 1.91 0.18 15.2 Mar. 19 19.9 Mar. 31 4.7 12 2.59 9 0.67 1.07 1.82 0.39 * Thaw. ILLINOIS RIVER AT BEARDSTOWN—1904. 8.6 Jan. 20 15.0 Feb. 1 6.4 12 2.46 *2 1.00 1.52 2.60 0.53 14.3 Mar. 1 15.2 Mar. 7 0.9 6 1.25 * 0.41 0.47 0.72 0.15 15.4 Mar. 21 18.5 Mar. 29 3.1 8 2.21 5 0.88 1.23 1.40 0.39 18.5 Mar. 29 20.0 Apr. 4 1.5 6 1.07 3 0.45 0.82 1.40 0.25 15.6 Apr. 25 16.3 Apr. 27 0.7 2 1.82 3 0.80 1.46 0.39 0.35 * Thaw. 267 APPENDIX “A.” TABLE NO. A-17—RAINFALL AND RIVER STAGE RELATION BY INDIVIDUAL STORM PERIODS. ILLINOIS RIVER AT MORRIS—1900. Stages and dates. Rise. Rainfall. Rise Aver- per age inch rise I rom. To. Dura- Dura- Great- Great- of per Amount, tion, Amount, tion, est est rainfall, day, Stage. Date. Stage. Date. feet. days. inches. days. 1-day. 2-day. feet. feet. 2.1 Jan. 17 6.2 Jan. 27 4.1 10 0.93 *2 0.30 0.57 4.41 0.41 3.5 Feb. 2 4.3 Feb. 4 0.8 2 0.67 1 0.61 0.67 1.19 0.40 4.3 Feb. 7 12.7 Feb. 9 8.4 2 0.90 2 0.53 0.88 9.34 f4.20 9.7 Feb. 13 10.7 Feb. 14 1.0 1 0.29 1 0.20 0.29 3.45 1.00 8.7 Feb. 20 12.0 Feb. 23 3.3 3 0.64 *1 0.47 0.49 5.16 1.10 6.0 Mar. 6 19.5 Mar. 12 13.5 6 2.52 * 0.97 1.06 5.31 2.25 8.4 Mar. 29 12.9 Apr. 2 4.5 4 0.84 3 0.41 0.72 5.36 1.12 5.6 Apr. 16 7.3 Apr. 19 1.7 3 0.54 2 0.28 0.42 3.15 0.57 4.1 May 7 5.5 May 12 1.4 5 1.39 3 0.56 1.04 1.01 0.28 3.1 May 20 4.9 May 23 1.8 3 0.94 3 0.40 0.73 1.92 0.60 * Thaw. t May be due to Chicago Sanitary District water. ILLINOIS RIVER AT LA SALLE—1900. Note —No gage readings for LaSalle, 1900. ILLINOIS RIVER AT PEORIA—1900. 5.1 Jan. 18 8.1 Jan. 26 3.0 8 0.75 2 0.38 0.37 4.00 0.38 7.6 Feb. 7 11.5 Feb. 13 3.9 6 1.05 2 0.72 1.05 3.71 0.65 10.4 Feb. 23 12.3 Feb. 25 1.9 2 0.54 1 0.50 0.54 3.52 0.95 11.3 Mar. 8 19.9 Mar. 16 8.6 8 2.12 *2 0.61 1.07 4.05 1.08 15.7 Mar. 31 16.9 Apr. 5 1.2 5 0.93 2 0.42 0.81 1.29 0.24 * Thaw. ILLINOIS RIVER AT HAVANA—1900. 4.5 Jan. 16 6.9 Jan. 24 2.4 8 0.87 2 0.52 0.87 2.30 0.30 7.0 Feb. 2 10.0 Feb. 11 3.0 9 1.64 5 0.72 1.07 1.83 0.33 10.0 Feb. 20 11.6 Mar. 2 1.6 10 0.57 1 0.54 0.57 3.86 0.16 11.0 Mar. 9 17.4 Mar. 18 6.4 9 2.09 * 0.90 1.03 3.06 0.71 * Snow. ILLINOIS RIVER AT BEARDSTOWN—1900. 6.9 Jan. 15 8.5 Jan. 19 1.6 4 0.83 2 0.52 0.83 1.93 0.40 7.7 Feb. 1 10.2 Feb. 13 2.5 12 1.81 5 0.75 1.09 1.38 0.21 9.9 Feb. 20 11.4 Feb. 23 1.5 3 0.61 1 0.58 0.61 2.46 0.50 9.5 Mar. 2 17.7 Mar. 19 8.2 17 2.39 7 1.14 1.25 3.47 0.48 I 268 FLOOD CONTROL REPORT TABLE NO. A-18—RAINFALL AND RIVER STAGE RELATION BY INDIVIDUAL STORM PERIODS. ILLINOIS RIVER AT MORRIS—FLOOD PERIOD, JANUARY-JUNE, 1898. Stages and dates. Rise. Rainfall. Rise per inch of rainfall, feet. Average rise per day, feet. From. To. Amount, feet. Dura¬ tion, days. Amount, inches. Dura¬ tion, days. Maxi¬ mum 1 and 2 . day, inches. Stage. Date. Stage. Date. 1.6 Jan. 19 6.5 Jan. 29 4.9 10 1.68 5 0.90 2.92 0.49 4.9 Feb. 6 9.1 Feb. 12 4.2 6 1.60 0.73 2.62 1.20 5.6 Feb. 19 8.8 Feb. 21 3.2 2 0.91 3 *0.72 3.52 1.60 4.2 Mar. 6 11.0 Mar. 14 6.8 8 1.17 4 *0.86 5.11 0.85 7.7 Mar. 18 14.7 Mar. 20 7.0 2 1.21 2 1.21 5.78 3.50 10.0 Mar. 26 16.5 Mar. 28 6.5 2 1.22 3 1.15 4.33 3.25 * Unknown amount of melting snow. ILLINOIS RIVER AT LA SALLE—FLOOD PERIOD, JANUARY-JUNE, 1898. 11.0 May 14 13.4 May 17 2.4 3 1.10 3 0.98 ?:ll} 2ei 13.4 May 17 19.4 May 23 6.0 6 2.12 4 1.26 12.8 June 9 13.9 June 13 1.1 4 1.85 7 0.55 0.60 11.0 June 25 13.2 June 28 2.2 3 1.12 1 1.12 1.97 ILLINOIS RIVER AT PEORIA—FLOOD PERIOD, JANUARY-JUNE, 1898. 4.0 Jan. 11 5.3 Jan. 16 1.3 5 1.15 4 0.72 1.13 0.26 5.1 Jan. 19 7.2 Jan. 24 2.1 5 2.04 5 1.02 1.03 0.42 7.2 Jan. 24 7.9 Feb. 2 0.7 9 0.71 1 0.71 0.99 0.08 6.9 Feb. 10 13.3 Feb. 23 6.4 13 fl .91 14 0.85 3.34 0.50 11.6 Mar. 9 15.8 Mar. 17 4.2 8 1.31 6 0.83 3.21 0.52 15.6 Mar. 18 17.4 Mar. 23 1.8 5 1.90 5 1.40 0.95 0.36 17.0 Mar. 26 19.4 Apr. 1 2.4 6 1.41 3 1.32 1.70 0.40 8.8 May 15 14.2 May 26 5.4 11 3.32 8 1.27 1.61 0.49 t Doubtful. ILLINOIS RIVER AT HAVANA—FLOOD PERIOD, JANUARY-JUNE, 1898. 3.2 Jan. 7 5.8 Jan. 14 2.6 7 0.95 4 0.75 2.74 0.37 5.2 Jan. 18 6.4 Jan. 23 1.2 5 2.04 5 0.98 0.59 0.24 6.3 Jan. 24 7.4 Feb. 4 1.1 11 0.75 1 0.75 1.47 0.10 7.0 Feb. 10 11.4 Feb. 28 4.4 18 fl .82 12 0.90 2.42 0.25 10.8 Mar. 10 14.9 Mar. 27 4.1 17 3.25 13 1.32 1.26 0.24 14.9 Mar. 27 18.0 Apr. 2 3.1 6 1.48 2 1.48 2.08 0.51 9.7 May 15 13.8 May 26 4.1 11 3.59 8 1.07 1.14 0.37 t Doubtful. ILLINOIS RIVER AT BEARDSTOWN—FLOOD PERIOD, JANUARY-JUNE, 1898. 11.4 Mar. 11 12.0 Mar. 15 0.6 4 1.30 \ 4 0.97 4.62' 0.15 12.0 Mar. 16 13.4 Mar. 21 1.4 5 1.15 3 1.09 0.94 >1.62 0.28 13.4 Mar. 22 14.8 Mar. 26 1.4 4 0.88 2 0.88 1.59 0.35 14.8 Mar. 26 19.9 Apr. 1 5.1 6 1.91 2 1.91 2.67, 0.85 10.8 May 14 11.5 May 18 0.7 4 1.24 3 1.01 0.561 0.96 0.17 11.5 May 18 15.4 May 30 3.9 12 3.53 13 1.40 l.llj 0.32 269 APPENDIX “A.” TABLE NO. A-18—Concluded. ILLINOIS RIVER AT PEARL—FLOOD PERIOD, JANUARY-JUNE.1898. Stages and dates. Rise. Rainfall. Rise per inch of rainfall, feet. Average rise per day, feet. From. To. Amount, feet. Dura¬ tion, days. Amount, inches. Dura¬ tion, days. Maxi¬ mum 1 and 2 . day, inches. Stage. Date. Stage. Date. 9.1 Mar. 11 9.6 Mar. 14 0.5 3 1.35 4 1.00 0-371o 47 9.6 Mar. 15 9.8 Mar. 17 0.2 2 0.12 1 0.12 1.67/ o.ior 1 * 9.8 Mar. 18 10.8 Mar. 21 1.0 3 1.09 2 1.09 0.92 0.33 10.8 Mar. 22 13.2 Mar. 25 2.4 3 0.94 3 0.88 2.56 0.80 13.2 Mar. 26 18.3 Apr. 6 5.0 11 1.96 3 1.91 2.76 0.45 Mar. 11 Apr. 6 *9.1 *22 *5.46 9.3 May 13 10.0 May 16 0.7 3 1.30 3 1.06 °- 54 ll.07 0-231q 38 10.1 May 19 13.6 May 27 3.5 8 2.61 4 1.50 1.34/ 0.44J * Sum. ILLINOIS RIVER AT GRAFTON—FLOOD PERIOD, JANUARY-JUNE, 1898. 4.6 Jan. 9 5.4 Jan. 13 0.8 4 1.20 4 0.79 0.67 0.20 4.4 Jan. 19 5.7 Jan. 23 1.3 4 2.08 4 1.02 0.63 0.32 5.5 Jan. 24 5.9 Jan. 27 0.4 3 0.68 1 0.68 0.59 0.13 3.0 Feb. 4 4.7 Feb. 9 1.7 5 (Miss. R.) 0.34 4.7 Feb. 10 9.2 Feb. 21 4.5 11 (Miss. R.) 0.41 5.9 Mar. 10 12.9 Mar. 15 7.0 5 1.34 4 1.01 5.21 1.40 12.3 Mar. 18 17.2 Mar. 23 4.9 5 2.14 5 1.09 2.29 0.98 13.8 Mar. 26 16.3 Mar. 29 2.5 3 1.94 2 1.89 1.32 0.83 12.5 Apr. 13 13.7 Apr. 16 1.2 3 0.79 1 0.79 1.52 0.40 9.2 May 14 13.6 May 17 4.4 3 1.30 3 1.05 3.37 1.47 13.2 May 20 18.1 May 23 4.9 3 2.64 4 1.46 1.85 1.63 10.3 June 10 Note. —Rises on February 9 and 21, on May 5 and on June 14 were due to Mississippi River stages. TABLE NO. A-19—RAINFALL AND RIVER STAGE RELATION BY INDIVIDUAL STORM PERIODS. ILLINOIS RIVER AT PEORIA—FLOOD PERIOD, JANUARY-JULY, 1893. Stages and dates. Rise. Rainfall. Rise per inch of rainfall, feet. Average rise per day, feet. From. To. Amount, feet. Dura¬ tion, days. Amount, inches. Dura¬ tion, days. Maxi¬ mum 1 and 2 . day, inches. Stage. Date. Stage. Date. 4.6 Feb. 12 13.8 Feb. 24 9.2 12 t4.62 t7 3.58* 1.99 0.76 13.1 Mar. 1 16.0 Mar. 9 2.9 8 f0.57 2 0.57 5.09 0.36 16.0 Mar. 9 19.9 Mar. 15 3.9 6 11.02 2 1.02 3.83 0.65 11.6 Apr. 18 15.4 Apr. 26 3.8 8 3.25 10 1.09 3.48 0.48 15.4 Apr. 26 16.5 May 6 1.1 10 1.33 4 0.79 0.82 Apr. 18 May 6 4.9 4.58 1.07 * Amount of accumulated snow (water equivalent), t Doubtful. 270 FLOOD CONTROL REPORT. TABLE NO. A-19—Concluded. ILLINOIS RIVER AT BEARDSTOWN—FLOOD PERIOD, JANUARY-JULY, 1893. Stages and dates Rise. Rainfall. Rise per Average TTrom To Maxi- inch of rise Amount, Dura- Amount. Dura- mum rainfall, per day, f GGt« tion, tion, 1 and 2 feet. feet. days. days. day, Stage. Date. Stage. Date. inches. 6.3 Feb. 11 13.9 Feb. 28 7.6 17 *4.26 t7 3.18 1.77 0.45 14.0 Mar. 8 17.0 Mar. 14 3.0 6 fl.86 10 1.24 2.41 0.50 12.4 Apr. 17 16.8 May 5 4.4 18 5.14 15 1.41 0.85 0.24 13.3 May 25 13.9 May 28 0.6 3 1.17 2 1.17 0.52 0.20 13.6 May 30 14.3 •June 2 0.7 3 0.96 3 0.87 0.81 0.23 * Accumulated snow, f Doubtful. ILLINOIS RIVER AT PEARL—FLOOD PERIOD, JANUARY-JULY, 1893. 2.0 Feb. 11 9.7 Feb. 18 7.7 7 *4.13 7 *3.05 1.86 1.10 9.7 Feb. 19 12.0 Feb. 27 2.3 8 *0.44 2 0.44 5.23 0.29 Feb. 11 Feb. 27 *10.0 *16 *4.57 2.18 0.62 11.6 Mar. 7 15.8 Mar. 17 4.2 10 1.41 3 1.37 2.98 0.42 11.1 Apr. 19 18.1 May 4 7.0 15 5.19 15 1.39 1.36 0.46 14.0 May 25 15.6 May 29 1.6 4 1.40 2 1.40 1.15 0.40 4.8 July 9 5.7 July 10 0.9 1 0.67 1 0.67 1.34 0.90 * Accumulated snow. * Sum. TABLE NO. A-20—RAINFALL AND RIVER STAGE RELATION BY INDIVIDUAL STORM PERIODS. ILLINOIS RIVER AT PEORIA—FLOOD PERIOD, MARCH-AUGUST, 1892. Stages and dates. Rise. Rainfall. Rise per inch of rainfall, feet. Average rise per day, feet. From. To. Amount, feet. Dura¬ tion, days. Amount, inches. Dura¬ tion, days. Maxi¬ mum 1 and 2 . day, inches. Stage. Date. Stage. Date. 7.0 Mar. 26 7.9 Mar. 30 0.9 4 0.60 2 0.60 1.50 0.22 7.9 Mar. 31 8.5 Apr. 4 0.6 4 0.39 1 0.39 1.54 0.15 8.5 Apr. 4 14.5 Apr. 12 6.0 8 2.06 5 1.53 2.90 0.75 Mar. 26 Apr. 12 *7.5 *16 *3.05 (2.45) (0.47) 10.9 May 2 21.9 May 9 11.0 7 5.34 9 1.99 2.06 1.57 14.4 June 18 15.6 June 22 1.2 4 2.50 4 1.75 0.48 0.30 15.6 June 23 18.5 June 28 2.9 5 3.40 8 1.87 0.85 0.58 June 18 June 28 *4.1 *9 *5.90 (0.70) (0.46) Note sharp crests at Peoria as compared to broad crests in later floods. * Sum. 271 APPENDIX “A.” TABLE NO. A-20—Concluded. ILLINOIS RIVER AT BEARDSTOWN—FLOOD PERIOD, MARCH-AUGUST, 1892. Stages and dates. Rise. Rainfall. Rise per Average From To Maxi- inch of rise Amount, Dura- Amount, Dura- mum rainfall, per day, tion, inches. tion, 1 and 2 feet. feet. I66t. days. days. day, Stage. Date. Stage. Date. inches. 8.8 Apr. 1 11.8 Apr. 8 3.0 7 0.76 5 0.42 3.95 0.43 11.8 Apr. 9 14.2 Apr. 13 2.4 4 1.97 2 1.81 1.22 0.60 Apr. 1 Apr. 13 *5.4 *11 *2.73 (1.98) (0.49) 12.6 May 3 18.4 May 15 5.8 12 4.06 7 1.63 1.43 0.48 13.8 June 23 15.4 July 3 1.6 10 4.89 11 1.77 0.33 0.16 Note effect of Sangamon on prolonged stages at Beardstown. Note lag in run-off as compared to later floods. ILLINOIS RIVER AT PEARE-FLOOD PERIOD, MARCH-AUGUST, 1892. 5.2 Apr. 2 11.2 Apr. 7 6.0 5 2.77 8 1.83 2.17 1.20 11.2 Apr. 12 13.7 Apr. 23 2.5 11 1.83 9 0.75 1.37 0.23 11.4 May 4 20.4 May 19 9.0 15 6.30 20 1.52 1.43 0.60 14.3 June 27 17.6 July 7 3.3 10 6.73 21 1.68 0.49 0.33 * ILLINOIS RIVER AT GRAFTON—FLOOD PERIOD, MARCH-AUGUST, 1892. 198.0 Apr. 1 207.2 Apr. 7 9.2 6 2.21 3 2.05 4.48 1.53 202.9 Apr. 14 207.0 Apr. 23 4.1 9 2.67 9 2.11 1.53 0.46 203.2 May 1 215.8 May 19 12.6 18 5.95 18 1.76 2.11 0.70 209.6 June 27 213.6 July 8 4.0 11 3.92 13 2.37 1.08 0.36 t GAGE 0=427 25 MD GAGE 0=43582 MD 272 FLOOD CONTROL REPORT. RAINFALL AND RIVER STAGES March 1 —August 31 , 1892 , Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer figure: A I GAGE 0— 220&b M.D GAGE 0 = 419.70 M.D. 273 APPENDIX “A.” RAINFALL, AND RIVER STAGES March 1 —August 31 , 1892 , Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer —18 P C FIGURE A 2 GAGE 0= 419 70 M.D GAGE 0=42725MD G4GE 0=43582 MD 274 FLOOD CONTROL REPORT. RAINFALL AND RIVER STAGES January 1893- —July 1893, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT OF 1928 FIGURE A3 43 5 36 M.D GAGE 0 = 486.55 M.D GAGE 0=53131 APPENDIX “A.” 275 RAINFALL, AND RIVER STAGES January 1898— June 1898, Inclusive REPORT ON FLOOD CONTROL OF TPIE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT OF (928 FIGURE A 4 GAGE 0= 427.2SM.D, GAGE 0= 431.67 M.D GAGE 0 = 435 82 M D 270 FLOOD CONTROL REPORT. RAINFALL, AND RIVER STAGES January 1898 —June 1898, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer ^ L.ifll, ri, IJLin.. Iftfljr. ,, REPORT OF 1928 FIGURE A 5 GAGE 0= 410 99 M.D. GAGE 0= 41970 M.O. 277 APPENDIX “A.” RAINFALL AND RIVER STAGES January 1898 —June 1898, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OP WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer FIGURE A6 GAGE 0= 435 36 ML). GAGE 0= 485.35 MD GAGE 0=53131 FLOOD CONTROL REPORT. 278 RAINFALL AND RIVER STAGES January 1900 —May 1900, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, 00031111105 Eogioeer FIGURE A 7 GAGE 0= 427.25 M.D. CAGE 0= 431.67 M.D. GAGE 0 = 43582 MD 279 APPENDIX “A.” RAINFALL AND RIVER STAGES January 1900 —May 1900, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT OF 1928 FIGURE A8 GAGE 0 = 410 99 M.D GAGE 280 FLOOD CONTROL REPORT RAINFALL. AND RIVER STAGES January 1900 —May 1900, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT OP 1928 FIGURE A9 GAGE 0= 4 4 4.13 WD. GAGE 0 = 466 54 M D GAGE 0=53131 281 APPENDIX “A ” RAINFALL AND RIVER STAGES January 1904 —April 1904, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT OF 1920 FIGURE A 10 AG E 0 = 427.25 M.D GAGE O = 431.93 M D GAGE 0 = 435.82 MD 282 FLOOD CONTROL REPORT. RAINFALL AND RIVER STAGES January 1904—April 1904, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting' Engineer FIGURE A I I GAGE 0= 410 99 M. 0. GAGE 0 = 419 70 M D. 283 APPENDIX "A.” RAINFALL AND RIVER STAGES January 1904 —April 1904, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting- Engineer REPORT or 1928 FIGURE A 12 GAGE 0= 435 82 M.0 GAGE 0 = 4 4 413 M.D. GAGE 0 = 4 27.25 M.D. 284 FLOOD CONTROL REPORT RAINFALL AND RIVER STAGES January 1913 —April 1913, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer FIGURE A 13 GAGE 0=41970 M D. GAGE 0=427 25 M.D GAGE 0= 43193 M.O 285 APPENDIX “A.” RAINFALL, AND RIVER STAGES January 1913—April 1913, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer FIGURE A I 4 aw 66 01^ = 0 30V0 286 FLOOD CONTROL REPORT. RAINFALL AND RIVER STAGES January 1913 —April 1913, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT OF 1928 FIGURE A 15 GAGE 0= 53131 GAGE 0= 53816 M D. GAGE 0= 617 32 287 APPENDIX “A.” RAINFALL. AND RIVER STAGES December 1915 —February 1916, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting- Engineer REPORT OF 1928 FIGURE A 16 OOrJ. U9I5 TO DEC.31,1915 GAGE 0 = 466.54 GAGE 0=496 60 MD GAGE 0= 736 75 M.D JAN.1,1916 TO APRIL 30,1916 GAGE 0 = 485.66 288 FLOOD CONTROL REPORT RAINFALL. AND RIVER STAGES December 1915 —February 1916, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting- Engineer FIGURE! A 17 GAGE 0=4J58?MD GAGE 0= 44413 M.D 289 APPENDIX U A.” RAINFALL, AND RIVER STAGES December 1915 —February 1916, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer FIGURE A 18 —19 F C 43193 M D. GAGE 0 = 474.78 290 FLOOD CONTROL REPORT. RAINFALL, AND RIVER STAGES December 1915 —February 1916, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer ii o u O $ REPORT OF 1928 FIGURE A 19 GAGE 0= 545.60 GAGE 0=51015 GAGE 0 = 4 66 58 M D. 291 APPENDIX “A.” RAINFALL, AND RIVER STAGES December 1915 —February 1916, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT OF 1928 FIGURE A 20 GAGE 0 = 41099 WD. GAGE 0 = 41970 M D. GAGE O = 427.25 MD. 292 FLOOD CONTROL REPORT RAINFALL, AND RIVER STAGES December 1915 —February 1916, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer FIGURE A2 I 531 Jl GAGE 0= 538 16 MD GAGE 0= 617 3? APPENDIX “A.” 293 RAINFALL AND RIVER STAGES October 1921 —April 1922, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer FIGURE A 22 GAGE 0= 496.80 M.D. GAGE 0= 736.76 M.D GAGE O = 48586 M.D. 294 FLOOD CONTROL REPORT. RAINFALL. AND RIVER STAGES October 1921 —April 1922, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer FIGURE A23 GAGE 0=435 82 M D GAGE 0 = 444.13 M.D. APPENDIX Sf A.” ■ 295 • RAINFALL, AND RIVER STAGES October 1921 —April 1922 , Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting- Engineer REPORT OF 1928 FIGURE A24 431.33 M.D. GAGE 0= 474 78 296 FLOOD CONTROL REPORT. RAINFALL AND RIVER STAGES October 1921 —April 1922 , Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer II o id o < o REPORT OF 1928 FIGURE A25 GAG E O = 4?7 2b M D GAGE 0 = 545.60 297 APPENDIX “A.” RAINFALL AND RIVER STAGES October 1921 —April 1922 , Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer l— 4111 -LiUk£_U* REPORT OF 1928 FIGURE A 26 GAGE 0= 51015 GAGE 0 = 466 58 M. D. 298 FLOOD CONTROL REPORT. RAINFALL AND RIVER STAGES October 1921 —April 1922, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting' Engineer FIGURE A 27 GAGE O = 4!099 M.D. GAGE 419 70 M D 299 APPENDIX “A.” RAINFALL, AND RIVER STAGES October 1921 —April 1922, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer FIGURE A 28 GAGE 0 = 53816 KiD GAGE 0- 6173? GAGE 0= 6 05.2 7 NAD 300 FLOOD CONTROL REPORT. RAINFALL. AND RIVER STAGES August 1926 —June 1927, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT OF 1928 figure: A 29 GAGE 0= 7 3 6 75 MO GAGE O - 48586 MO CAGE 0- SJIJI APPENDIX 301 A 7} RAINFALL AND RIVER STAGES August 1926 —June 1927, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer riGURt A30 CAGE O =444 13 M D GAGE 0= 496 80 MO. 302 FLOOD CONTROL REPORT. RAINFALL AND RIVER STAGES August 1926 —June 1927, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer figure: A3i 47478 CAGE 6 = 43582 M D. 303 APPENDIX V RAINFALL AND RIVER STAGES August 1926 —June 1927, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer flGURE A32 MAY I 8 19 I 7 TO 5EPT 281927 GAGE 0" 43193 GAGE 0= 510 IS _ 5EPT 28,1927 TO JUNE 30,1927 GAGE 0 4JI67 304 FLOOD CONTROL REFORT RAINFALL AND RIVER STAGES August 1926 —June 1927, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT OF 1928 FIGURE A33 GAGE O - 4? 7.25 MO GAGE O — S4SS0 GAGE 0 = 447 48M0 305 ArrENDIX “ a .” RAINFALL AND RIVER STAGES August 1926 —June 1927, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer r IGURC A34 —20 F C GAGE O = 419 70 WO 306 FLOOD CONTROL REPORT. RAINFALL AND RIVER STAGES August 1926 —June 1927, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER . DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer JACOB A HARMAN, CONSULTING ENGINEER FIGURE A36 XW66 0l*=0 30 V 0 307 APPENDIX “A.” RAINFALL AND RIVER STAGES August 1926 —June 1927, Inclusive REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting- Engineer FIGURE; A36 308 FLOOD CONTROL REPORT. APPENDIX “B.” TABLE NO. B-l—REACHES FOR STORAGE AND BACK-WATER COMPUTATIONS. Stations.* Locations.! Stations.* Locations.! 0-15 Grafton. 613-633+300 Pheln’s Lake. 15-50 Marshall’s Landing. 633+300-655 Havana. 50-80 Coon Creek Landing. 655-676 Liverpool. 80-124 Hardin. 676-707 Clear Lake. 124-166 Keache’s Landing. 707-722 Senate Island. 166-201 Kamnsville. 722-760 Copperas Creek Lock. 201-227 Pearl Landing. 760-781 Kingston Mines. 227-264 Huck Horn Landing. 781-790 Manleton. 264-299 Florence Landing. 790-807 Pekin Landing. 299-325 Griggsville Landing. 807-820 Pekin. 325-354 Earl’s Ferry. 820-848 Weslev Citv, now Creve Coeur. 354-376 Meredosia Island. 848-855 Peoria. 376-397 Eagle Island. 855-877 Averyville. 397-409+750 LaGrange Locks. 877-882 Peoria Heights. 409+750-425 LaGrange Landing. 882-908 Mossville. 425-442 Reich’s Landing. 908-948 Rome. 442-452 Briggs’ Landing. 948-961 Chillicothe. 452-462 Grape Island. 961-1005 Lacon. 462-469 Beardstown. 1005-1034 Henry. 469-493 Frederick. 1034-1069 Swan Lake. 493-526 Browning. 1069-1093 Hennepin Lake. 526-542 Butlersville. 1093-1130 Hennepin. 542-572 Bluff City. 1130-1162 Spring Valley. 572-590 Anderson Lake. 1162-1185 Peru and LaSalle. 590-613 West Matanzas Lake. * Note. —Stations in 1,000 feet. t Names of towns, ferries, landings, islands or lakes within each reach. TABLE NO. B-2—ILLINOIS RIVER CROSS SECTION DATA—REFERRED TO CENTER OF REACH. APPENDIX “b.” 309 tp 05 QJ Tp CO Cl* QJ t-i d d cr m 05 oo o £ o ►d £ 'a; d CD Cl £ Es o -4-> Cl -*-> Cl CO t-H Tp a o • r-i Cl > CD W *H qj -*-» d £ I & o G\ »-H o 05 o »o d .2 3 *-> cq o d .2 %-* d -i-3 rQ CO CO CM OO o CO CO O 05 o TP 1C CO lO CM o T-H CO »o CO CM oo 05 CO co o CO o ^p CO oo T-C r- O CO t-- CM 05 05 ^p | CO co 05 CM CO 1 o o TP j o CO *

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CM CM OO o 05 05 lO to CO 05 r*H rH 05 -rf rH CM CM »o CO OO rf 05 rti CO CO CM CM to rH co oo r-H rH CM r-P o 1 co oo rH 05 1 I CM Ol »o “l 1 CO o CO T-n rH L— OO 1 rH CM CO CM | 05 1 co CO 05 CM 1 CO l 1 Ol rH CO *T 1 | o oo 00 rH I O to to 1 rH CM co O 1 oo -f OO Ol r-r CO O 05 o »o to rH 1 OO CO CM co O 1 1- | CO »o 1 CO ! co OO « | O CO t-H | 1 co o CM CO CO I CO OO Ol t— 1 CO rH CO oo °i | rf r^- rH oo H | to CM 1 CM Ol to I to | rH CO rf 1 CO 1 r*< »0 05 "i i H | 05 CO T-H I ^ o to 1 1 Ol Ol to | Hji CO OO rf oo 1 CO CO CO O OT j CM O CO 05 CO rH CM CM 1 CO rH CO T— H I CO 1 OO Ol o H CM tO oo 1 CM OO o 1 rH Ol »o CM 05 OO T-H CO co o to to CO oo rH N oo T-H rH to 1 ^ CO o CO 1 1 to 05 rf | oo rH I H CO 1 1 rH rH O I O 1 1 05 CO r- CO 1 I Tf* r— CM | CO oo to I 1 1 ^ to 1 1 1 rH o 05 | 05 CO CM oo CM 1 o CO N rH | CO o 1 l ^ 1 rH OO | 05 OO t-r CM 1 Ol ' CM r-p r^- rl | co-r 1 Ol Ol 1 1 rH to 1- 1 CM CO • o r— CM O CO CO -HO, « 1 H 1 T-H rH | co | r - oo »o CM 1 Ol 1 CM rH HP 1 ^ 1 ° o 1 1 o o 1 1 -H — 1 i • i i i i i i i i i i i i 1 i i t i i i i i i i i i i i i 1 1 i i • t i 1 1 1 1 1 1 1 1 1 1 1 1 • 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 d 1 aS i 1 o 3 1 © . a .n *2 oS © as © p. Pi © > o 1 a o • rH - 4-5 «« c 3 © rO £ a *3 - 4 -> o rd H -3 aS > © l a H "d 0) c 3 >_a w OO Mile 42.99 to Mile 50.00. Station 227 to Station 264...1901 Low Water Elevation 425.4. Width at Low Water 1,010 Feet. Area below Low Water 7,032 Square Feet. Distance 37,000 Feet. APPENDIX “B.” 311 a Cj XI I a> > o a o • fH 4-3 d > o H o »-q o 03 03 03 Cl a o • M ■4-3 d -p> CO o -P3 HP co CM a .2 o3 -4-3 CO d d X i fH o X -4-3 T3 d o • >H 4-> o3 oj >-d ' 1,688 444 16,579 25,818 42,397 4H a> - 03 HP CM to r—1 1-4 CM HP HH OO CM o T-H CM CO TTf Hp HP CO T—H CO hP CM P- 03 d oo HP to r ^ CO «• - — — VS Vs T-H 03 CO to 03 to T"H CM T-H CM OO CM CO o > o 03 O to to CO CO O -P to CM CO O to to CM HP 03 P- •CO oo HP P- oo to t—H to oo Hp > HP OO CO T-H CM t-H CM t-H CO hP OO CM 03 oo t-h CO CO CO CO o HP OO 03 OO T-H Hp t"- CM d CO P- t-h T-H CM CD t-H CM CO 1 to CO oo ^H »o T-H P- OO OO CO CO CM CO cO CO O CM CM 03 HP CO P- CO HP H O t-H 1 CO co o' CO p- o 1 T-H CM CD T-H CM 03 **P o oo OO O T-H CO co co 03 r-H CO lO T-H co o CO CO H HP OO Hp CO CO HP CO r-H HP — - . TTf Vs CM to oo CO T-H CM CO OO T-H T-H CO 03 hH t-h T-H CO r-H OO 03 cd p t-H to to 03 HP CM CO CO O CO to CD 03 CO CO 03 CO CO HP oo t>- to © d HP CO T-H oo ^H Hp CO T-H tO co T-H T-H s ^ t-H r-H 03 CM o oo oo »o Hp HP lO 03 T—H CO t-h 03 o O !> 03 CO HP CO CM HP Hp CM CO 03 4H O CM Hp t-h CM Tf t-H CO HP o pq T-H HP to T—H t-H ® 43 t-H t-h OO r-H T-H 00 03 O oj »o CO 03 r-H O co CO 03 OO 10 a to CO hp r ^ CM CM HP P- CO Hp a> 5 CM HP CO CO CM CM CO 2 V, CO HP T-H t-H t-H r-H o o CO oo T-H CM HP r-H o CO CM P^ o T-H CO 03 to to CM HP to co CM CM HP to HP o T-H CM p-l CM CO t-H T-H to hH T-H OO 03 CO oo T-H CM oo T-H O CO CO to CM CM CO 03 CO CO OO HP CM T-H Hp CO co 03 a T-H HP CO to 03 o O .2 HH r-H T-H T-H 43 t-H r-H CO CO to oo CO d CO o CM 03 r-H O CM co to CM > CM CO r^ CM HP T-H Hp t-h CO oo CD T-H HP CM CO OO 03 03 w o' O T—H 03 03 OO §3 03 03 03 to HP to CM to -P o 43 OO CM OO T-H O Hp CO d HP OO oo oo 03 03 d o H W OO »o Hp CO CO o CO CO CO to ptH d d 4-3 CO o 03 03 CM d o • M 4-3 d -43 in »o OO H*H CO o CO HP CO oo CM to HP HP CO T-H r-H 03 CM CM T-H CM HP T-h 03 o 03 CO HP 03 CO CM to HP OO 03 oo T-H t-h 03 T-H CM CO oo CO OO HP CM CM HP co HP to HP CO r-H to rH CO T-H T-H CM CO Hp to o oo oo O HP Hp r-H to to HP OO HP CM r-H HP O »o T-H CM CO CO co CM oo oo I HP CO co 03 Hp HP CO co 03 T-H CO 03 CM | T—< T-H CO CM CO CO co 03 HP HP to o to Hp HP OO 03 T-H T-H QO o' r-H t-h CO CO CM T-H O y-4 r-H HP t-h »o CO HP H^ Hp r-H to r-H O CO oo T-H T-H CM P^» t-h OO HP CM HP 03 03 03 co Hp 03 CO CO r-H oo CO T-H CM CO O T-H OO 03 T-H HP CM CO to CO HP co CO CM T-H CO Hp T-H CM T-H 03 CO CM o to CO O oo 03 CM HP CO oo T-H T-H co to CM r-H Cl CO OO I co CO 03 CO to CM oo r-H HP O T-H t-h T-H to »o o T-H CM HP HH O ,-H t-H CO co r - CO t-H HP OO CO Cl t-H CO HP oo rH T-H CM CO [>. HP T-H CM CO HP rH CO 03 Hp t'- CO CO CM CO CO T-H rH co to to oo CO to CO CM to GO CO HP oo oo CO r-H CM HP T-H T-H to HP CM CM HP 03 CO N O r- CO HP T-H T-H CM T-H CM CO T-H T-H 03 CO CO CO CO CO np Cl CO HP CO T-H T-H CM T-Hi T-H r-H CM 1 oo o oo ^p CO CO 03 Cl CM HP HP JO o o ^H T-H T-H P- 1 T-H r ^ hp rH 03 CO 03 CO CO t-H HP T-H OO o 03 o' r-H 1 1 1 1 1 1 1 1 1 1 1 l 1 1 1 1 1 1 I 1 1 1 1 1 • 1 1 1 1 1 1 M 1 • 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 • 1 • 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 f 1 1 1 1 1 1 a as ; d P ! rO 1 1 d fli a> f-l fH a> > o 1 cl _o M *3 g-s d ’’d 4-3 4-> Xi a o rd 4-3 d CD i a H TJ o oj >-C £ w oo TABLE NO. B-2—Continued. 312 FLOOD CONTROL RErORT. 40 © CO © O J G rG -*-> 40 cd CM G O G > C ion. = “ Cl 0 ) G *G - 43 > - 4 —' a o rG - 4-3 G > © L c H T3 a> cl >^= £ H CO CD i^H O -M >a o CO CD CD O O ©_ cm" CM CD O G G © CD Ph CD Fh rt G cr co CM CO Fh © £ o & "3 G* G CD »H T3 r— CM G C ’-4-3 G > © S Sh © -4-3 G £ £ O o CD CO r— co G .2 -*-* G W O »o CO G .2 *H-3 G -*-> CO 05 1 C5 OCO CO CO , HP 1 CO O CO 1 ^ 1 05 CM 1 CO Tt’ o I 1 CO 05 1 CO CO OO I —« *o co -p 1 CO 05 GO CO I OO CO o 1 G _o cl S'© G G -4-> -4-3 rG £ O pG G > © i C H T3 © G > -G w oo »o o H-3 CM © © O o o CD o G C/3 Q CD G > £ O G -G -4-3 rs CM G .2 ’-3 G > © H F-l © -4-3 G £ £ O ■J O CD 03 CO G .2 G +3 CO co r^ co G .2 -4-> G -4-3 m o o 0 0 O 05 40 r-H (M CO 00 CO 0 CO 40 05 1—4 co ^4 05 CO T-H CO CD 0 t- 00 rtr Ol 05 r-H oo 05 O »o co 0 O 05 04 l-H 05 OO Ht4 r-4 00 OO yp CO 0 oo yp OO 40 yp 40 O 05 cd O r-H 03 i—4 1—4 o 05 r-H CO <74 40 40 0 oo 05 OO 00 40 TJ4 OO CO CD r-H r-H T ~‘ oo CO 05 OO O 40 GO 05 r-H oo yp O -H 05 40 05 OO 00 r-H 0 r—H o 40 74 40 05 »o yp 05 O 04 oo yp 05 r*4 CO 40 CO O OO r-H O 05 yp rf 05 CO yp yp r ^ 00 40 oo yp CO co O 40 co Hf r-H 05 CO 05 05 r-H CO yp CO 40 05 oo yp CO 05 05 40 r-H 40 L- r-H 05 05 05 OO CO r^4 Hf 05 co CO CO 04 05 40 40 40 O CO 1“H OO yp i r-H CO CO 05 o yp 05 r-H CO CO yp 05 40 yp 40 05 TJ4 yp 40 r-H l — CO O 05 O 05 yp -74 05 05 r-H yp CO t— 40 TJ4 CO OO 40 r-H CO O CD CO CO cO CO co yp CO •74 00 0 05 40 CO CO r-H yp rH CO 05 OO CO T*4 O CO r-H -r-fH CO 05 ■74 40 CO OO 40 CO 05 40 yp r-H 40 o rT —H »o CO co Hf 05 CO r-H ^J4 04 CO OO 40 OO r-H 05 CO —4 yp OO CO yp GO 04 CD CO OO 05 OO ■74 O OO 05 yp CO 0 CO CO —4 yp OO 40 CO 40 r-H 40 CO 00 t ^ CO 40 05 r-H TT< Tt< CO 0 OO Ol r—H CO yp •74 ao 05 0 yp CO 04 40 CO yp HJ4 yp yp CO 05 CO 05 CO 05 CO yp 05 CO O CO OO 04 T-H r-H T}4 05 05 Tt< 05 OO r-H 01 O 05 OJ CO 00 05 CO 00 0 00 CO -74 rH O r-H CO •O OO CO —H 01 05 r-t 01 CO 40 05 CO 05 OO r- ■^4 Ht4 05 r-H r-H r- 00 r-H r-H r-H 1 1 4 1 1 1 1 1 1 xt 1 1 1 1 1 1 1 1 1 1 1 1 1 1 t 1 1 1 t 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 a 1 G 1 • G 1 © 1 G b ci © 1 G »H Fh © > O 1 G .2 "-*-3 AA *h c « G ^ a G *G H>3 O rG -4-3 G > t. a H O cl >X £ w OO Station 397 to Station 409+750.1901 Low Water Elevation 428.0. Width at Low Water 812 Feet. Area below Low Water 4,925 Square Feet. Distance 12,750 Feet. APPENDIX “b” 313 o T-x O —' IO IO io o »o H CO CO CM oo 1 o co CO Ol oo 1 - T-H o o O 05 05 »o iO o OO OO Hp 05 !>. CO oo t-h CM IO CM I'- f-H o 05 O r- »o HP io r ^ CM HP t-H 05 T-H oo CO t-h IO hP CM CO T-H o oo I O IO IO »o HP o CO CO Hp ++ ,0 „ oo Tf —1 IO CO CM »o 1 - 1 o O CM CM *o Hp 1(0 IO o HP CO CO o oo »o o CO CM CM -+ T—H o 1 «o O hH T-H »o 1 hp o -+ Hp 05 IO oo CO 05 CO T-H T-H CO 1 o IO O 05 05 »o HP IO CM 1 - HP • t-H i>» oo oo OO oo CO o ^ 01 i 4 o 1 ^ O r- >o HP o ^ T-H 1— HP -*V 05 CO oo 05 r^- r- 05 »-H —^H T-H o I CO o io IO iO HP IO o »o + 1 ^ CO T-H r— oo o 05 o ! o CM o co CO F—1 Hp O 05 05 CO hP 05 CM T-H oo t-H CO GO OO T-H 05 o O T-H v-H o i -+ 05 OO L— CO 1 ^ CM ^ oo i CO IO OO N t—i OO o o O 05 05 oo 05 CO »o 05 Hp 05 CO CO 05 CO r-< o 05 o ^ ~p CO -H IO CO HP o oo OO * P- CO o IO H t^- o oo o »o IO hp CO T-H hp HP CM O CO 05 CO « i"5 _Q l r- 1 Cl s t- a> c a -*-» o H D t- Cj . z, o > w o u D D o »o CM D o £ c3 a; CD £ D t-i cr m CM CO i>T c3 > D c3 D Fh 05 O oo d oo I'- (D CD W oo Fh (D -+-> c3 £ £ o c3 "d CO HP o > D H D O hH O 05 »o CM HP a .2 c3 ■+-> 02 O o »o r>- 4- 05 o .2 -4-5 c3 ■w 02 o t-H ! co 05 IO IO O CO 1 - ® **1' 1 IO CM CO I T-H T-H CO 1 co (M 1 oo CM o CO oo Hp O IO 05 -P Hp 05 »o CO 1 ^ o GO io CM oo 05 HP T-H 05 05 CM Ol oo -rp OO 05 oo CO CO 05 CO • O *-H ^ 1 1 OO CO CO Ol 05 05 o o ooJ 05 F—H + CO I 05 05 05 1 1 HP T-H CO o I r— CM IO t- 05 1 O GO oo °9J CO CO 1 CO oo HP -P T-H CO CM CO 1 CM HP CO oo 1 T—H CO oo 1 - CM CO IO HH I'— T-H T-H Ol o 1 oo o CO CO io 1 co CM 05 T-H HP HH OO o CO I CM o CO 1 T-H T-H CM o t- 1 o »o »o o CO ! r- I- Hp 05 1 H 05 O o CM OO O 05 HH HH o CO O HP HP oo CO r— i.o CM IO + CM CO 05 «o O I IO 1 O CO CO t-H [ CO 05 CO Ol M HP HP -P 05 CM I co oo r-H 1 I hH o HP | O CM Ol oo CO ; OO HH 05 CO H f CO CO 05 ^H 1 oo 1 1 1 1 1 1 1 I 1 1 1 1 1 1 1 1 I 1 » 1 1 1 1 1 1 1 1 1 1 1 1 Si 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 • 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 • 1 1 • 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 1 1 1 1 • 1 1 1 1 1 1 t £ 1 a , 1 cl D , Si 1 b cs C3 fl) D 1 Fh Fh D > o 1 CJ _o m b C3 (U cl +—* XI HH c3 + a i a o H -2 d a >x: w oo D D D Fh 02 CM OO o Fh o c3 o ►-3 D X2 c3 D u> < CO oo D D 05 I- Fh d o -*-> 05 Hp o oo £ O T3 £ hp CO HP .2 c3 D 5 Fh D O ►J o 05 a .2 as 4-> r/2 o »o CM Cl 02 o CM 1 CO HP o »o »o I- Ol o »o HP CO o o oo o 05 CM CM o T-H CO IO »o *o CM O CO IO Hp OO 05 r- 05 y —» CM o o I CO CO CM IO »o 1 r - oo cO .O Hp CM T—I HP | r'H 05 HP H- CM ° 05 I CO 1^ CO IO Hp 1 CM CO 05 HP | HP CO 00 IO HH CM o I oo I CO oo Hp IO 1 HP HP CM ■o 1 ^ | HH t ^ 05 | co CO HH Cl o CO 05 »o • o Hp CM CM IO »o Hp CO O CO IO ^ CM HH CM o 1 50 CO o CO IO HP f ^ T-H oo »o HP O CO co io co t-h T-H cm o »o CO CO IO HP CM 05 t-H »o HP IO IO T-H | TF >0 o 1 hH CM o Hp co CM oo »o HP r - HP »o Hp 05 oo oo CO HP oo hH —* o CO I co co 05 »o HP CM IO »o HP | HP F-H IO CO HP hH HH ° 1 Ol CO HP o IO HP I ^ CO T-h ^ J OO HP CO CM CO CO hH T-H o T-H co IO f-H »o Hp CM H HP IO Hp CO 1- o CM CM IO H-1 T-H ‘O o CO CO CM CO Hp t - 05 IO HP 05 T-H T-H CO T-H T-H CO I 05 1 t-h oo HP 1 CO hp r ^ T-H Hp 1 HP ! CM Ol IO 1 1 r-H f-H CM T—H IO oo | 05 oo r^- 05 CO 1 OO IO HP CO HP L- IO CO I o r-H 1 IO I r— | CO 05 CM CO 1 CO io CO 05 t-H Hp 1 CM 00 o 05 o 1 ^H ° 1 co oo o oo 1 - 1 CO OO CM o HP CM 05 05 GO I io OO T-H 05 CO hH O T—H 1 HP HP Hp oo oo 1 1 r 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 . 1 1 1 1 1 1 1 1 1 1 • 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 * 1 « 1 1 . ' 1 1 1 • 1 1 1 1 • 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 £ d ; 1 aJ oj : c3 Xl 1 b el D 1 03 fl) Fh Fh D t £ V Fh 43 03 c3 *— 1 K* o o Cl'S c3 x: -*-> a ^ a f!h £ o H T3 • H ** D d> cl > si w oo 314 FLOOD CONTROL REPORT. T3 ' ! ^r 03 CO CD o ^r 40 ^ CM CO G -w o O -H T-H • -H »o »o CO Tf o Q CO O 03 ^r CO CM CO -M o o o cO CO »o 40 — o T—< -cr 03 o Pm - F. - OO CO CM CD CM CO o | 03 O T—( »o TT CO L- CO cr -r CO m CO 00 CM o CM CO o oo O CO CO »o 1 — CO — r- | -r rr cm co oo - - — 1 t- — 00 CD CM CM -4-3 o O T-H G >o -r co O co ^r CO CO 03 co O CO CM CM o o co o - CM T-H CM P-4 O I CO 1 O T-H r-H »o 1 1 co O CM »o -r ! CO 40 CM CO - - - 03 i | co o O T-H CM CD o CM O co CO -4-3 »o ^r t— CM CO G ^r 03 CO 40 - - — CM »0 oo T-H t-H is o O —H o »o 1 TV CO 03 40 1-3 T-H CO oo -4-3 CM nr CO G *-H ^H F-4 o 1 o o o CO »o -r ^H 40 CO "3 »o 1 ^ tT T-H I T-H CO 40 »o I 1 03 | O T-H CO CO CM oo o OO OO co •*r 1 ^ CO CO TT —H o oo 40 CO _H G CM CO T^r oo CO O CM -T oo CO •»—< -4-3 CM G T-H > o 1 ! 40 T-H CO O 1 CO 1 CM 40 w t ^ M 05 1 1 o' T-H 0) T-H -4-3 »o ! 40 CO G oo CO 00 T-H o kT 1 ^ o T-H — j o o T-H O 1 1 1 1 I T-H 1 1 1 1 1 o 1 1 1 1 1 03 1 1 1 1 1 l i l i i i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i 1 l i i i i 1 CM 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 »o TT 1 1 1 1 1 G 1 1 1 1 1 C -4-- G +■3 A 1 1 1 1 1 1 GG c G 1 G O 1 G -2 Jh e* « QJ G F—4 G -p G -4-3 fG c o O rG G > o 1 r* U, *H H -4-' G O c3 > J3 C/2 H OO o to oo IO oo -p> P*H o o o G £ & o hJ 5S o F < G -C T3 CO G .2 G > d> W t G K*' £ o h-3 o o G r/3 o -p> CM »o **r G .2 -+-> g -4-> m o CO CO OO 40 1 40 1 cm o 05 HT oo CO hT co OO ^h CM CO o CM CO O CO 40 »o CM CO OO 03 hT 03 OO CO CM CO T-H CM CO o CO CM oo 40 • O L- 03 CO 03 rr 03 03 03 CM ~h HT T-H CM CO o o co rr o 40 40 CM CM 40 03 HT O -H *—* CM t-H CO t— O G .2 3« c3 o »q oo o o o G is £ o £ o *3 g CD Ph CD CD P*H **r CO 03 P- CD £ o -*-) G rG -4-3 nG s £ CO g .2 ’-4-3 G > CD s (-4 CD -4-> G is £ o o 03 03 CO hT G .2 -*-» G -4-3 rfl o -4-3 CM CO **r G .2 -4-> G -4-3 m O HT t^F CO o 40 40 ! CM CO 03 03 o r— !>. 40 co T-H t-h CM HT O 1 CO 03 co ‘O 1 10 L- CM o 03 o oo 03 HT 40 03 t-h CM CO o CM 40 CM 40 40 CM 03 CM 03 HT t-h OO O CO hT OO t-h CM CO o T-t T—H oo 40 *o co CO 03 TT t-h 03 T-H CM CO CO t-h CM co o o TT 40 40 CM CM »o 03 CM O CM T-H CO •rr T-H Cl CO o 03 I co o 40 HT 1 L- 03 03 TT CM O CO O CM CM 1 T-H CM CO o OO 03 CO 40 TTT CM 40 oo 03 hT CO T-H ^r 03 *-H o CM CO O 1 tn. iO CM 40 1 HT 1 CM o 05 HT CO CM CO OO O oo 1 CM CM o CO j ^h oo 40 -rr CM 03 T-H 03 HT hT CM 03 CO CM o 40 TT 40 HT 40 CO 03 ^r co OO CO 00 hT T^ CM o ^r L- CO O 40 CM CM 40 03 hT 40 hT OO 40 CM t-H CM o CO 03 CO 40 ^r oo CO 03 hT 40 HT O tT co _ T-H Ol o 1 ci l-H 40 CM 40 nr CM 40 OO 05 1 H' CO 40 ! CO 40 03 T-H H o 1 T-H t-h OO »o I hT L- CM 03 03 hT CO CO CM 1 CM hT 1 1 T-H T-H o r— HT t-h ■*r CM OO t-H oo hT CO hT T-H CO »o 1 T—H t-H o 1 ^ O CO CO »o 1 CO T-H ,0 CO »o I ^ 03 CO 1 CM CO 1 T-H t-H 1^ oo O 03 03 CM CO 1 CO -H Cl **r CO 00 r-H F-H CM H T-H CO 1 ^ | CO 40 oo CO 1 co ' CO 00 TT TT I ~ 0 °. o 1 1 o T-H 1 l T-H T-H 1 1 1 1 1 1 1 1 1 1 1 t 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 44 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 t 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 t 1 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 a G • 1 G a> i G x> b g o 1 G .2 *H G G G 13 -p> o rG G > L c H *T3 0) c3 • H > -C £ w OO Mile 88.83 to Mile 93.37. Station 469 to Station 493.1901 Low Water Elevation 434.2. Width at Low Water 706 Feet. Area below Low Water 5,471 Square Feet. Distance 24,000 Feet. APPENDIX “B.” 315 % oo tp 05 CO CM o 40 CO CO OO TP CO 40 r-H o CO CO p-T I - - P- 00 1-H o r—' 40 40 CO 05 CM Tp OO P- co CO Tp P- 05 oo 05 P- CO P- r-H 05 »o 1 ^ OO CO ,-H Tp o OO oo Tp oo *-H CO P- r-H oo oo 1 co CO o 4-0 1 Tp CO co o Tp 40 P- CO CO 40 05 1 CO r-H P^ r-4 CM 40 r-H CO 05 tP P- CO CO CO tP r- o oo »o 40 o 40 r— oo i rH 40 05 o OO 40 CO oo CO CO r>. 00 CM r-H CO 40 o CO 05 40 40 -*r CM oo O CO CO ^H CO -p r-H »o o 05 r-H CO 40 CO CM CO 40 CM 05 r-H CO ^ CM CO r-H o oo r-H P- oo co CO P- CO o o CO CM 05 CO P- CM 05 CM r-H CO oo r-H i-H CM oo CO r-H CO ■yp oo CO 40 r-H Tp r-H r-H CO CM H CO »o CO CO 40 oo rH CO CM CM •*p 40 P- OO 40 Tp co o p^r r-H rH CM oo »o OO 05 CM CO O -H CM CO CM r-H CO CO t: a CD 1 C3 m f-H (-4 CD > O 1 a _o rt a, C3 rH c3 -Q a O 4-> Cj > i c H 73 <» c3 >-S w OO CM CO 05 05 o CO CO 05 03 C/} 23,623 454 322,786 17,704 340,490 CO CO CO o c o rt oj ~ci -4H rO CJ o c3 U 2 E-i ai rt >-a w oo »a CO O CM CO 05 05 © i •P5 o 4C (-> © & o +2 c3 rd -4-J »o CO TP id o • rH c3 > co . Tp 05 rH TP T o CM CO r^r 05 CO *H TP 40 »o rH 40 N CM »o TP CM co 05 CO Tp O 40 »o 05 Tp OO CM CO TP 40 I o O 00 oo rH Tp io CM 1 Tp CO o 0° I TP OO CM CM CO o 05 40 05 Tp TP CO 40 TP o TP TP 40 CO 40 40 CO 1 r—' (M o GO 1 40 O 40 CO CO rH -P 40 TP Tp co o CO TP I o ' — 1 rH 40 1 1- 1 IO r—H CO CO OO CO rH CM T 00 40 CM CO | 40 CO CM rH O CO I O cm (M r—H co 1 H CM CO Tp o o CO rH 1 CM CO oo o 40 O CO CO o CO »—H 05 TP 05 40 Tp 40 CO 1 1 1 M 1 1 1 1 1 1 1 < 1 1 1 1 1 1 1 1 1 G 1 cl 1 Cl 1 CD 1 G2 b ®j o cd o c3 a> -*-> ^ G o c3 > JD L a H 72 4) rt >G3 Ss Cd oo TABLE NO. B-2—Continued. 316 FLOOD CONTROL REPORT. CO CO oo o m co ci o (D h—I © o © © CO © o G G c n 5 © CD S S-. CD -*-> G O o 05 Cl »o G O G -*-» r/} o ci Tp »o G O -*-> G GO © Tp CO ^P »o »o Cl Cl TP CO Tp ■TP Tp oo 05 to co CO 4-h 40 o CO CO 05 Cl »o »o r- O oo O Tp I - oo 40 05 »o lO r-H Cl r-H TP PH r-H O Cl CO -^p N »o IQ Cl 05 r-H CO TP r-H r-H CO 05 CO iO ^H r-H r-H CO T “ H r-H »o y—< CO 05 Cl Cl to I — t- 40 CO Tp Tp 40 o 05 CO ^ r-H O ’-H Cl r-H »o o OO -P Cl Cl »o TP co r-H »o TP 05 05 05 05 CO CO o 05 r-H r-H r—H »o 05 CO 05 Cl Cl TP Cl -p CO Tp TP co 05 r- co o OO ’—I o »o oo OO TP Cl CO TP 05 CO CO r-H Tp O I- oo 05 OO Cl o t— r-H 05 to I- CO 05 Cl 'TP | r-H 05 »o T 05 r-H o O0 OO Cl r-H CO oo »o CO 1 OO TP Cl Cl TP 05 o o GO tp j co »o 05 O r-H 1 CO r-H O I »o I CO 05 Cl »o TP 1 1 ^ oo CO to Tp J 40 oo TP Cl o CO 1 I 40 r-H CO »o Tp CO Tp 1- Tp Cl 05 TP O C-1 Cl cO 40 o 40 TP ^h »o o I CO OO 05 o -p TP to o CO ■^p Cl co 05 CO OO 05 1 CO TP CO Cl OO TP Cl oo -p Tp Tp 05 Cl ^p CO o CO CO r-H 05 o CO TP Cl O 05 05 co ^p co Cl oo r-H ^p CO TP 1- CO »o oo CO 1 1 Cl CO Cl o | OO TP Cl r-H -p 1 05 r—H CO ^p TH GO »o 05 t ^ 1 r-H Cl to 05 I CO 05 40 r— CO OO 05 oo 05 -Tp I OO H o Tp CO F- r-H 1 r-H Cl Cl oo 1 r-H TP 40 CO CO ! r-H oo 05 CO ^p | 05 40 TP CO I OO CO 40 1 T- Cl l- 05 05 oo CO CO Tp CO r-H CO ^p Cl 05 Cl Cl 40 40 r—H r-H l- CO | TP V—H oo CO oo >o TP 'TP | »o CO 05 - 1 Cl to o | to | O 05 05 o 1 CO 1 O CO CO CT> -r I 05 t v — eo . T • 1 1 1 • 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 t 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 • 1 1 1 1 1 1 1 1 1 1 c 1 G i G 1 cu , X 1 1 s g © 1- S-4 © 1 G ^ »3 G ►> o _o G *3 G -4-J ■X! -4-5 -45 G "9 c c o H T3 © Oi cs w ou © © 3 t-H © o 05 o 05 40 G O G -w TO o ci r^- »o G .2 -4-5 G -*-> TO o | TP 05 05 00 40 1 »o o oo TP oo o oo Cl oo © |h h © 1 o CO 05 r-H © 40 »C0 Cl © Cl TP co Cl © r-H oo r-H CO r-H r- o I Cl 05 CO Cl 40 1 »o co r-H 1 Tp CO 40 © r-H | O CO © to r-H © 1 r-H o 05 to Tp 40 »o 1 Cl 05 Cl Cl T n N . © r-H 05 to Tp r-H CO rH »o r—H o o 05 © 40 »o to CO CM Tp oo o © r-H N 40 Cl r-H Cl r-H Tp r—H r-H o 05 05 05 oo »o TP Cl r-H TP CM TP CO CO © r—H CO TP © r-H r-H r-H CO r-H o oo 1 05 r-H © 40 Tp I- oo © Cl Tp 1 co »o © - r r-H 1 »o CO oo r-H o r-H r—H 1 T o hr I 05 CO ci »o Tp Cl TP Cl Tp r-H OO © r-H Tp Cl © r-H 05 r-H © 40 CO 05 to Tp TP o oo 40 TP OO r-H © o Cl Cl TP TH OO r-H © o 1 »o tp r - r-H Cl Tp O co N Cl Tp CO CO © o 1 Cl T-H CO r-H 1 r-H oo o Tp Tp 05 CO to TP OO Cl r-H o Tp O CO o Cl o Cl r-H CO r—H r^- 40 co I TP rH 40 o TP 1 CO 05 Cl 05 Tp 1 o oo © 05 Cl 05 H 1 »o © r— Cl 05 CO Cl o Tp Cl to oo CO TP r—H r —4 Cl 05 1 Cl 05 r-H 1 TP »o 40 1 TH Cl to oo Tp Cl- r-H CO CO I TP 40 Tp © oo 1 Cl oo © CO Tp 40 o r - Tp r— TP co CO tp OO co co Cl CO 40 05 Cl 05 r-H r- CO CO CO © Tp TP 05 G *o CO co CO ! r-H Cl Cl oo | HH oo CO CO 1 OO O oo CO TP | OO Cl © TP © © 1 • 1 rH r-H o 1 40 CO oo 40 I CO Cl CO oo -1 T Cl TP © CO 1 © IO r-H r—' »o I 40 IO O Cl 1 CO 1 1- Cl © CO T © hr 1 1 CO TP - 1 1 1 1 • 1 1 G 1 Cl t G 1 a> i G JD 1 b o 1 G .2 ^ rt Ci ID G 33 -*-> £> c o -G -*H G i a H 0) Oj ci >JS 3 CO O tp © © © o © co Cl © © G G © © © (h G G cr TO ci tp Vh © G £ * O £ JD 33 rD G © 1-4 <1 -U> © © o co In © -4J G £ •s O - 4-5 G 73 >o CO G > © 3 »-. © G > 9* o p-3 o 05 co co G .2 -4-5 G -4-> TO o -W o 05 40 G .2 -4-5 G -4-5 to »o to »o co oo CO ‘O Cl TP © - © TP © © © © Cl CO to 1 CM | 40 CO oo 1 Tp 1 © 40 TP 1 ^ 1 © 40 TP 00 CO ! Cl © — I © CO CO r-H TP 1 © Cl r-H T | CM CM “i Tp © GO r-H »o © 40 CO oo TP © © oo Tp CO H oo (M TP L- ^H r—1 © 1 05 O CO CO »o CO © © © Tp TP 40 It Cl 1 r-H © oo © oo © CO CO »o CO 40 CO oo © TP © © ® r-H © 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 » 1 1 X! 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 t 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 1 1 t 1 t 1 1 1 « 1 1 1 1 1 f • 1 t • 1 1 1 1 1 1 1 1 1 1 1 • 1 1 1 1 1 i 1 • 1 t 1 1 1 1 1 1 1 1 1 1 1 1 c G • 1 G CD 1 G -Q 1 b C3 G G> CD It Sh CD > o 1 G .2 ’-+H is G 33 o rT2 G > ci >ja £ w oo Station 613 to Station 633.1901 Low Water Elevation 436.0. Width at Low Water 694 Feet. Area below Low Water 4,848 Square Feet. Distance 20,000 Feet. APPENDIX “B.” 317 CM to oo CM to -rf CO CO O r—H 00 oo CO r4 t—H CO CM CM O (M t-h to CM CO CO OO CO T-H T-H co p- t-H t-H CO oo CO o CO CO o to rH r^H to CO to CO T-H r-H to CO CM T-H T-H CO OO CM CM CM 05 to o »o to CM CM 05 T-H t-H Th to o ^H t*H CO r-H ^ 00 CM 05 »o O to CO CM 05 CM T-H t-h CM tO oo T-H H CM CO o o ^ oo to 1-H CO CM CO to T-H T-H 1-H CO i-4 t-H (M o 05 o oo • o 05 o o O oo CO 1 OO CO T-H T-H -F T—H 05 CO 1 1 1 1 1 t 1 1 1 1 1 1 1 1 1 1 » 1 t I i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 t 1 M l l 1 l 1 l l l 1 i l 1 1 1 1 I 1 ( l i 1 1 1 1 l 1 t l l l 1 1 1 l l l l l 1 i 1 l i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i » i i t i i i i i i i i i i t i i i i i i i i i i i i i i i i i i • i • i t t i i i i i i i • i i i • i • i i i i i i i i i • i • i » i i i • i i i i i i i i i i i i i i i i i • i i i i i i i C 1 d i d a> , J0 b c3 d O 1 f-* s m « g'o d *d 4-5 A 4-5 •45 d G i a O H 35 O ja £ w OO CD O • d _o 54 b rt a> d *d -45 Td 45 45 d 5) c L a o H 32 CD -a is w oo »o to 05 CM yd £ CO CO Tj* d .2 45 c3 > 2 C ►-3 O 05 CO co d o • r H ■4-5 d 4-5 CO o 4-5 to »o CO d o d 4-5 CO o CO »o »o o p- to '-F 05 Tf T-H T-H CO oo T-H t-H t—< CM CM T-H CO o to to 05 p- to P- 00 co T-H 05 CM CM t-H 05 T-H T—H t-h t-h CO o OO CO t-H r- to o oo 05 T—H oo oo CO T-H oo o 05 t-h t-h CM o CO to CM to CO P- T-H T-H CO TtH T-H T-H p- o oo t-h t-h CM o CM to r-H co to co P- CO 1 Tt< Hji O to T-H CO o CO T-H T-H CM o T-H ‘O to o to 05 CO co T—H CM CO 05 T-H to 05 CM O I o to 05 t- 1 to CM to oo T-H 1 t-h CM CO i—4 'TF 05 CO T-H CM o 05 to CO GO Tt« to to o T-H rP 05 OO oo t-h CM OO T-H T—H cm o I CO to P- CM oo ^ CO T-H r- CM T-H T-H OO o 1 T—^ CM o p- 1 to r-H CO p- ~p r-H IF to -p 1 o 1 G _o d JD L c H 32 « 03 > JS 2s w oo 318 FLOOD CONTROL REPORT. T3 0 > 3 . .E O 05 '■+j c CO CO o i-H O d CD t-i -< CD D £ (X) »o Jh CD +-> c3 £ o hJ o3 XI -+-5 T5 • i* CO CO 4*4 C O P> O s *H CD -+-> 03 £ £ O o o o C .2 ’•*2 d -*-> CO o -4-> co r- co a o o3 h-> CO o CO i O —< y—i CO ! r - co CO oo | OS I-H ^p 1 o ^ m OO 1—1 05 o »o o o o co »o ^ oo CM oo CO Tt< i co ^ o 1 T—1 05 o O 05 05 CO *o 1—1 05 o oo co »o 05 I T-H CO — oo o CO 1 o oo oo CO >o ' oo »—• 05 oo o 4-f ’Tf CO CO 05 1 CO o CM o CO »o m co oo oo co ^ o ^4 (M CO O 1 y—t O CO co CO »o CM »0 r- oo oo 00 CO r—4 oo 1 m i— co o o O 40 m CO »o 05 CO oo CM CO in CO o 1 05 I O 4* CM CO 05 40 oo T-< CO 00 L- O p- *~P i-4 »o ° 1 oo I O CO CO r- 1 ^ 1 **P i-4 40 ! I CO 1-4 4^ CM O CM 1 'Tf 1—1 40 ° 1 ^ 1 O CM CM '*r ' co o ^ 1 lO »o F- 05 1 CO 4-f o CO O 1“H y—f »o TfC co »o r-H CO coos °°. CM CO CO 4-P ° 1 »o I ' o o O 1—i 1 -h r- OO CO I ^ 1 1 03 nj CD 1 Sh o > o 1 a o g 4> o3 r—4 c3 4-5 4-> o Xj 4-5 rt i a H "O CD a> rt > ja w OO D 0) £ o o o d X3 -i-> s O co 4*1 C3 O g3 > Q> w U CD c3 fe £ O A H o 05 CM CM C3 O o3 -4_> CO o r^l o c .2 H-5 c3 H~> CO o 1^ O (M 03 CO 40 O 40 in TfH 40 05 4*4 CO " 40 CO 03 i—H 1—4 CO 1—4 i—4 o CO O 05 05 CO 40 P- 05 CO l>- -TT4 1 4^ O CO CO CO 03 40 t'- O i—4 i—H l-H o 4^ o o o CO »o 1-4 05 o 4^ CO 05 CO CO 40 4*1 o 05 i—4 i—4 1-H o CO O CO CO CO »o OO CO 1—1 4^ 40 CO 05 CO OO 4*4 03 OO i—4 o i-H o (M O ' I 4^ 4f 03 CO 1 i-4 05 i-H 4*4 40 O 40 1 O 4*4 4*4 CO 4 -V 1 4*4 O 4*4 t>l t''- i—4 oo CO 4*4 05 CO 1 CO 4*4 O 4t4 1 o o o CO 4-f4 *-4 40 CO 4^ 4-F O 4*4 4*4 CO 1 OO oo CO 1 Ol CO o CO 1 O CO CO o -t4 1 OO 05 o 4^ I 1 40 CO CO r-4 !>.' 05 03 03 ° 1 a r ^ 03 | 03 O — 1 O OO oo ~r CO oo 1-H r^- 1 OO 4*4 CO ■4f i 1 05 CO CO 1 1 0 1 ° 1 O 4*4 4*4 CO I -p CO CO 05 col -* i o°o oo o o 1 1 i-H r i i i i i i i i i i • i i i i i i i i i i i * i M i i i i • i i i i i i » i i i i i i i i i i i i i i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 t 1 1 1 » f • 1 1 1 1 1 1 1 1 1 1 1 1 1 t 1 1 1 1 1 1 1 1 1 1 1 1 1 • 1 a c3 1 c3 O i a o m b 2 a c3 H-5 4-5 X^ C o X3 4-5 c3 > X3 w oo 4*4 05 co 4*4 4*4 i>- cd co d CD £ OO CO c3 £ & o c3 XI -4-5 TJ £ 05 CO 4*4 £ .2 c3 > CD H s- (D -4-5 c3 £ is O o 05 o CO C o +5 d CO o CM CM a o • >-h 4-5 c3 4-5 CO 03 OO P— CO o 1-4 40 05 Oj 4*4 i-H in 03 03 4*4 co CO 1—4 4*4 03 P- 40 CO OO 1—4 »o OO CO 1 -H o 4*4 H o 03 03 O 4*4 4*4 CO i“H 4*4 03 CO 40 CO OO 1—4 40 05 CO o 4*4 l-H 4*4 CO 03 OO CO i-H 03 l-H 4*4 03 »o l-H co 4*4 l-H 40 CO 40 i-H o 4*4 i-H 05 i-H 03 CO 03 05 03 i—4 CO 03 4*4 05 CO 03 i-H 40 4*4 1-H co o 4*4 1—4 4*4 40 03 4*4 03 CO 03 1—4 CO 03 co co O 1—4 40 CO i-H o 4*4 1 -H oo o 03 03 l-H 4*4 1 03 1-4 CO 03 03 40 CO oo i-H »o 03 CO 40 o 4*4 l-H CO 4*4 03 O -H l-H 03 CO 03 i-H CO CO CO i-H 40 i—4 05 o o 4*4 1—4 N 05 03 OO o OO i-H i-H 03 03 1 O 1-4 CO 1*4 »o O 40 40 OJ 4*4 i-H 03 CO 03 | CO O CO i-H i-H 03 03 1 05 | 05 CO 03 4*4 1 GO h o °-1 4*4 o t- oo 03 1 ! 4*4 05 CO 1 03 03 GO co o i-H 4*4 l- r- »o o 4*4 O 1—4 03 03 03 05 ^H i-H 03 03 1 L- | m co OO *—H | 4*4 1 co co 05 °. I 4 O CO CO 03 1 | o oo oo 1 1 i—H i—4 i-H 1 CO 1 CO CO co o j 4*4 | »0 05 4*4 051 4*4 | o o l-H 4-4 1 oo oo CO 1 1 -H OO 1 40 03 CO »o 40 1 4*4 »o »o o col 4f i-H 40 1—4 j CO CO —H OO 1 4*4 1 4*4 CO r- 4*4 1 4*4 | 05 1—4 o 4*4 1 4*4 4 O 40 1—4 j I 4*4 L- ^H 1 »-H O 1 CO 1 co CO 05 05 1 4*4 ! 4*4 i-H col 4 1 0-1 40 j I CO CO 05 CO 1 03 CO CO 05 03 I 4*4 »o co oo 05 4 CO 05 40 l-H »0 o | i-H CO CO CO 40 1 4*4 CO 05 03 m | 4*4 r- co 1 in CO 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 • 1 1 1 1 1 1 • 1 1 1 1 1 1 1 • 1 1 1 t 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i i i i • i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i • i i i i i i i i i i i i i i i • i i i i i i i i i i i i i i i i i i i i i i i i i i i i • i i i i i i i i i a rt * c3 u Sh O 1 a o -w b d ® d "3 H-5 ■is iQ X o X -4-5 c3 > O i a H TJ • li a o3 >-a £ H OO 319 APPENDIX “B ” (M 05 Tp o o 4^3 05 CO M CO Ph C3 £ O hi & O "3 ctf -■ Pi CD 5 Pi . a o o3 4d m © oo O *-4 1 ,-H to CO 05 1 CM • o T—H o tP O 05 05 to Tp CO CM to CO Tp O to to CM co oo O I CO O CO co t-H Tp OO 'Tf CM Tp TP CO 05 CO 1 T-H lO o CM O CO CO oo Tp P- CO CO CO TP 05 CO CO to CO o T-H o o o 05 Tp 05 OO tO tP to t"» CO IO 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 M 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 . ' 1 1 1 1 1 1 1 1 1 1 1 t 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 a a ! 1 ci O a o ^ rt aj? 5 <13 ci "3 4-3 XI 4-3 ■s > JD -9 a l a o H T3 • r~* X3 ^ w oo tp oo cm tO o f£< o 4-> cm CO 05 Tp 0) W Pi CD 4-3 ci £ £ o o 05 r- o oo a o • f—« 4-3 c3 4-3 m o 4-5 O 05 o M 4-3 aj 4-3 m CO 1 05 Tp co o CO »o ^H -T^ CO CO 1 ^ O CO CO »o oo CO T-H CM CO oo t-H HP *o CO »o to TP 05 CO CO 05 to tp CM T—H CM CO OO CM o CO »o OO -Tp CO CO CM CM to tp' r>- T—H CM CO CO to o to CO »o CM TP CO CO Tp 05 »0 TP CO co o T-H CM CO to CM OO o CO »o CO CO o CO to oo Tp CO to 05 T-H T-H CO ^p 05 CO »o CO to 05 CO CO CO -Tp T-H T-H CO CO to oo T—H CO CO CO TP o CO »o CO CO CO OO TP CM CM TP t'-T T—H T-H CO CM CO CM »o CO »o r— co o CO TP Tp CM CM CO CO T-H T-H CO T-H o o o co »o T-H CO TP CO Tp TH O T-H CM CO »o TH t-H CO o oo *o CO ‘O TP CM CO TP t" CO o T-H CM TP T-H T-H ° 1 05 TP CO o to 1 ^p OO CM CO TP co co o 1 T-H T-H CO t-H t-H CO oo Tp Tp oo T—H TP CO CM »o CO Tp O 05 05 TH O T-H T—H T-H oo to Cl oo CO Tp T-H CM CO CM TP CM 05 o o TH T-H o CO 1 oo o oo 05 **p 1 CM CM Tp T-H Tp Tp »0 05 1 05 05 »o I to oo oo CO T—1 ^p CO TH »o T-H TP CM oo o 1 00 05 co Tp CO CO 05 Tp CM T-H CO Tp T-H T-H CM oo oo »o CO »0 Tp 05 TP Tp T-H »o TP TP Tp 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 • 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ' 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 a 1 ctf i ci a> i x> C3 Q; o 1 a _o m b £ X! 4-> 4-> a > .2 -9 a 9 c o E-i 73 X3 rs w oo 320 FLOOD CONTROL REPORT. ~3 © P c o O i o o 4*4 4*4 G .2 *-£ G > 0) s © "3 £ o o o G CM OO G C o8 «a C£ O r- o oo G .2 -*-> G •4-) OJ to 03 to ^P 03 CM iO CM CO 03 CO CM CM ^ CO OO T-H to »o OO 1 o oo oo 04 to | O CO CO 1 CM OO o CM 04 CM to ^ —« »o »o 1 ^ | to CM CM »o 1 r^- co o 1 1 | co OO CM i 1 03 04 1 co ^ to »o CO | O co CO CM »o tO CM t^. OO “1 04 co — oo CO 4-4 -rp »o »o I to o to 04 1 to 1 CM CM Tt< r^J oco CO CM 1 ^ —3 to CO ■~p »o 1 1 o *rp CM to | O 4-H *" ] co oo 4—' CM*1 1 t-M O 04 CO — Tf tO CO i to oo CO CM to L- O oo L- 'rp | oo co 04 1 oo o 03 1 CM — CO »o CM | 004 04 CM to 1 to o »o r- 1 cc oo CO - - | CO 04 03 0 I'- 04 1 I 03 | -rt< 04 4—< 04 o t~ | to CM »o 04 r- 03 lO CM CM 04 04 03 4—4 1 4—4 ° 1 CO 1 ! to co CO 1 -r co *-p oil -r CC t- *rp 04 | 03 CO CO 4—4 »o | to 1 to O to CM ^ CO r-- T»< CJ CO 1 ' ; : 1 1 1 1 1 1 1 1 1 1 1 1 t 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 G G i G 1 © . 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Station 855 to Station 877.1901 Low Water Elevation 441.3. Width at Low Water 1,485 Feet. Area below Low Water 12,137 Square Feet. Distance 22,000 Feet. APPENDIX 321 “b.” CO T-H oo o oc • o t-h O oo oo CO CO CO 05 40 -*3 40 CO L- 05 CO O hP CM CO CO 0 o HP HP 40 o CO CO r-H HP rp CO TP T-H 40 hP 05 CO CO CO CO o 1 CM lO p O o O | O CM CM CO CO o o o CO CM 05 r-H O HP 1 CM 05 t-H HP I HP CO T-H CO | O 05 o 40 CO | CM CO CO 1 »o CO 05 0 O 1 co cq 40 CO 05 CO O CO o 05 o co CO 40 CO CM 40 CO 40 40 oo CO O Hp r-H tP 40 ci CO ^P CO L- Hp CO p oo 40 m CO oo cq t-H hp CO OO 5 Cl CM 40 co CO o »o 40 o oo i o o o o 40 oo CO t-H CO 40 | Cl OO o o hP O 05 o tP HP o oo 05 CO HP CO t-h -43 CO 40 T-H CO Hp CO OO 0 1 CM CM Hp CO P I hp o Hp o 1 I O HP Hp p 40 1 P IO CM 05 4 0 05 D- CO 05 Hp I o hp 40 0 T_ ' HP | 40 05 40 CM hH »C CO CO 1 T-H O Cl 1 Hp CO p 0 1 1 Cl Cl TP CO 1 I CO ‘O co cr o CO o oo CO CO 1 40 1 05 CO CO CQ ' CO 40 O CO co 05 H I o o o 05 HP HP o HP CM 1 1 oo CO CM o HP OO Cl 00 o OO I 1 CO CO p — Cl CO CO »o | CM O CM CO o 40 O Cl cq 05 »o CO CO hP oo »o Cl co oo oo Hp ! ~ ^ co fH 0 H-3 HP Hp r-H 40 CM ■ O o 1 ^ 1 O co CO CO »o CO 05 CO 40 40 1 HP »0 05 CO HP CM 05 CM £ 40 i ^ 1 CO CM CO CM CM O CO o cq Cl oo o co co CO 1 T—' r-H CO CO CO o o o o CO o o o CM »0 1 o *-h £ 40 40 05 40 HP CO HP HP 40 05 o T—H HP O CO Hp (M | 05 05 oo o CM O p- 1 CM CM »o X! t—H t-H CM CO I — — — m - - — cm CO O CO r-H t-h CO r-H CM CO * 1 1 T-H CM CO CO OO 40 CO o CO o oo oo CO HP CO T-H 40 CO rp O O o CO HP P-* T-H oo T-H HP HP o o o — - •• — HP - - — cq O 05 05 TP T-H T-H CM T-H T-H CM T— H T-H CO »o CM O CM c o 40 | o ci CM p Hp 40 CO OO Tf p- o r- t-H HP CO co 05 -p cq rp 40 r-H CO cS t> cq OO P 40 O o T-H CM o s r-H t-H CO Hp CO 40 r—H o ^P O CO CO 05 HP P T-t< CM oo HP O 05 05 »o xr r-H t-H CO T-H HP CO T-H HP »- t-H co CO CM 1 ! i i i 1 i • i 1 CJ X) 1 : ; i a Cl i c c3 cS 0 , cS rt ® 1 ,Q 1 i h CS q; 0 »H O -4-3 JD i 1 Co Q} o »H f~i 0 > o i a £ x £ c — C3 a. ci *3 -4-5 P- OO t-4 O i a o •gs d'S cj x\ H-> -4-3 0 i a O H 0 .2 rC d -9 0 i 0 o H "d o 0 <3 cJ • H >• o D C3 >XJ E£ w oo CQ w OO —21 P C p 05 1*3 O ■43 40 o p CO • t-H CM —< CO p -4-3 05 CO oo »o CO o CO oo p o OO HP I HP O 40 - - - r 40 I Cl rH CO 1 OO 40 CO I- T-H r-H 1 u P- 1 CO CO CO 05 0 1 »o r~— r—i 05 -*-3 t" ! ^ CO 05 40 c3 - > 40 CO oo »o P Hp Cl 1 r-H O «o 1 »o CO oo Hp 05 1 IO 40 HP o 40 1 HP 05 P p £ »o . O CO p p HP r-H 0 r-H a 0 Sh 40 Hp r-H O T—i -p »o CO oo HP co *o 05 OO I »o ! rp Cl O 05 ! HP 1 40 O CO HP I 05 CO P •43 1 1 H-tH CO OO 0 O 1 o I Cl oo o rO 05 1 >o 1 CO o p CO I •H 40 05 HP T3 HP I HP IO CD ; np co CO p- 1 05 | cq o Cl Tf Hp 1 P Hp T-H CO HP I 1 CO P HP »o HP I 1 - ~ 1 05 CO CO r-H CO CO p cq co 1 »o cq p o HP cq p 05 0 CO Hp | O 40 IO HP 40 r-H co" -43 0 CO co CO > p- p 1 co hp P t- -p ‘ Cl o CM HP HP -rp CO s HP | O 05 05 tH CO Cl 40 0 P- CO CO co cq 3 OO HP HP CO oo Cl HP 05 cq t-H eS HP 40 P CO Cl Cl »o p. »o 05 CO p CO Hp 40 CO CM h-1 Hp CO O P hH HP T-H 40 CO cq Cl HP t-H 1— Hp cq o CM 1 Hp Hp cq o Cl 05 Hp 40 05 HP 1 CO p cq o 1 r-H CM HP 1 p 1 CO 40 cq P 1 05 HP P CO o 1 Hp H 40 p CO 1 CO I CO O HP 1 rH CM CO 1 1 OO 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 o 1 1 1 1 1 05 1 1 1 1 1 c 1 1 1 • 1 o 1 1 • ' 1 -*3 ' 1 0 -43 M 1 ' » • | 1 CQ a 0 1 o -43 0 rO 1 1 1 b c3 0 Q} o3 0 f-. CM 00 00 0 fH 0 > o 1 0 o T l-H •43 J> a 0 "3 -43 o o • PH rd •43 0 > 0 s (h 9 H •43 aJ -43 GG tU C3 > J3 OO TABLE NO. B-2—Continued. 322 FLOOD CONTROL REPORT. »o 05 P^ p~ 05 -P> © © o o o o 4*4 © © c d -p © © © p rt o 1 CQ o 05 Pi © -P <3 is is O yl £ o < © c 8 © Pi < © © 4*4 CO o Pi © -4-3 d is * o iJ -p c3 - 4-5 S is 4*4 C .2 *- 4-5 © t < w Pi © -P c3 £ £ O p3 o 05 CO 4*4 05 a .2 - 4-5 o »o OO CO o -rr 05 CO OO 4-H 05 CO H}i O 4-H 4*4 »o (M CO oo 05 »o CO Tfl L- oo -rr HJ4 OO to CM 05 r-H CO CO O 4-H oo 00 CM o CM »o CO ^4 »o CO Tj4 to co CO lO CO 05 Pr» CO o oo OO 1 —H >o -h oo »o 00 CO i-H tO o »o CO »o CO oo »0 CM eo o »o 05 Hji CO CO (M CO CO to lO CO oo ^ CO r— o J—i OO O oo 05 »o 00 4-* 05 o 05 CO CM tO 05 ^-4 4-H CO CO »o o OO co o »o 05 05 CO CM 4*4 "rr 05 CO CM co oo 05 CO CM to CO 05 CO 05 CM CM 4*4 05 CM CM to CO OO ! »o oo CO »o I »o o CO to 1 CM CM ■*F 4*4 1 »o »o o 1 CM CM to oo CM H}4 CO CO o CO -*F N 4—4 oo 4*4 O CO CO CM CM *rP CO ■*f o CO CO ^ O o CO 4-4 to ► 4*4 CO ^H h- 4- CM CO oo •o I CO co 05 05 CO O CO 1 CO 4-H CO CM 05 i“H CO CO 1 ^ i »C CM CO 1 co o l-H i *°.® CO CO I 00 »o CM o CO | CM OO o o 'TV co 1 —^ CO o CM »o »o o 4—' CM 1 1 1 1 1 1 1 1 1 1 1 1 1 1 M i i i i i i i i i i i i i i i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 l l l l l i l i i l l l 1 i l a d i i a © . d £> ■ h ci © p. 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OO 4-H to 05 CO o 4 P to CM OO CO O CO CO CO CM oo 05 !>. CM 05 »o to N 4-H OO oo ^P tO 4*4 05 to 4*4 CM CO tO CM 05 to co o 4-H to i-H lO 4 P l>- to CM to OO 4-H o 4t4 (M i-H to 4*4 r— 4-H CM to 05 05 05 to 4^ 05 co CO to CM O CO 4*4 e3 © d © p Pi © > o 1 d o S’® d ~d -p> H-> ^2 a o rd cS > © L a E-i ~o • H © c3 > J3 iS H OO Station 1005 to Station 1034...1901 Low Water Elevation 441.8. Width at Low Water 817 Feet. Area below Low Water 7,357 Square Feet. Distance 29,000 Feet. 323 APPENDIX “B.” 0 CM CO 0 CO co CO CO co 05 p^ HP to CO CO 10 -*f CO 00 05 - I 05 lO HP OO to r-H r— 05 iO HP T-H OO 40 CO 05 to 1 co 1—1 OO CM 0 05 OO P- rH to co »o 05 IO Hp to 05 HP IO 0 00 05 CO CO »o t-4 OO CO to CM rf CO HP Hp O i-H t-H 40 lO OO CO to — 0 Hp CO 00 »o 05 CM T-H CO HP to CO 05 to 05 P- CO t-h co 0 CO •*f P- CM 10 O ■ CM CO CO CO CO CM to Hp CO CO CO CM CO 00 1 CO CO CM 00 co 1 ^ ^ (M CO 0 1 ^ 05 t*< CO HP OO 1 1 1 I 1 • 1 • • 1 1 1 1 1 1 1 1 1 c cj ! a g ! 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T3 a; g o O I CM w o £ H d « H CM o CM © o -*-3 p^ o CM © © o o o © o G G © © 0 u G G CT CO o 40 tH © +3 G £ o d fe ^© G © *h d -4-3 G • rH Tf Tf Tf G .2 ’-3 G > © H f-. © & o ►d O 05 o CO G .2 d G •+3 m CO 05 O G O G -*-> CO p^ CO I"- t'r. O Tf co CO CO CM CO Tf oo oo 00 CM 05 CM O T-H CM rH rH CM CM CO ^ o CO CO co o CO Tf CM r-H CO 00 ^ 05 CO 05 r-H r-H r-H 05 r-H r-H 40 Tf CO o t- 05 Tf 05 CO CM L- 40 oo OO r-H o rH rH O 40 OO CO Cl CO 40 CO 05 40 Tf 05 CO 40 id r-r r-r 40 N r-H 05 05 | TJ4 40 05 T-H *o CO o CO Tf Tf ^ 05 CO 1 O CO t-r 1 t ^ r-H oo oo 1 cm 05 Tf »o | r-H oo CO Tf 1 O r-H r-H Pr | CO co 05 I co -H o O 05 05 Tf »o t— CO o Tf CO rH 40 40 r-H 40 r-H cO CO | O co CO t— 40 CO O CO o Tf 1 H t- rH p^ oo ^ CO -T 1 r-H CO 05 40 CO 05 4-0 40 L'- CM CO Tf CO 05 CO CO r-H CO »o rH 40 CO | Tf | 40 O »o o 40 1 1 40 ^ 05 t. T I 50 o 1 CO 40 CO rH © Tf 1 o p- OO -r | O co CO ~ 1 rH oo 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 34 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 • 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 c G 1 G © . X J b cj © 1 G Qp *H © > o 1 a q •gj? C3 0) G "g -4-3 '-4-3 -2 a o rG -4-3 G > Jlj i c H 'H © G >rG C£) OO © © P*H O o © cm* CO © © G G © © © Eh CO G a 1 co CO 05 CO Eh © - 1-3 G £ * o PI is o » i © G © t- d © © plH 00 o CM d P^ CM (h CM © © -4-3 G £ Ss o & O CM O -u d G rH CM rG Q) T5 a »o Tf Tf G .2 d G > © 3 © o d o 05 Cl CO G .2 -*-> G -1-3 CO O -*P O CO G .2 -4-3 G -4-3 CO v-H rrf | r-H CO ref Tj< CO CO Tf o CO -r | “-l O | CO 05 CO 1 40 N o CO O CO CO CO CM rH CO CM 40 rf 05 Tji 05 OO rf rH CO 40 CM O 05 05 O CO 40 OO CO CM Hf CM CO 05 40 P^ CM Hf rH CO OO | 40 CM Hf CO 1 CO o r—H 1 O 05 ® ! -« 50 oo 1 rH 40 o o P^ 40 CM oo CO 05 CO CO o Hf OO CM CM Tt« CO CO CO CO rH 40 40 05 P-T OO 40 r-H 40 rH O CM o OO 40 CO CM 40 oo CO r-H rf 40 1 oo CM rH CO 40 1 »o O OO oo 05 OO P>» 40 CO OO CO Ol r-H Tf 1 p^ Tf CO 40 | 40 o OO Hf 1 oo o 05 CO | Tf ^ OO 1 CM rH CO o CO o N o 40 OO CM o oo 05 CO CO CO O CO -ef CM rH CO oo 40 o o o 05 40 oo o oo CO rH CO CO CM 05 rH rH CM o 1 CM CO 40 40 1 OO P- »o Tt< | Tf OO CO CO | CO rH »o CM CM CO 1 CM CO oo CM 40 rH Hf »o CO O -H rH CO O rH —H rH rH CM o CM i o 05 05 CO »o 05 rH o o I CO rf CO | cod rH rH o rH O CM CM 05 40 CO 05 40 05 CO CO CO r-H CO 05 CO 1 r—< o o o »o »o CO 40 co CO oo CO 05 CO rH OO o rH o 05 1 O oo oo Hf -rf 1 'Tf CO CO OO CM o 1 00 03 o OO | O rH y—t 40 -P O rH rH CM 40 40 o P- oo o r>- 1 O ref 40 rrf I *o oo CO CM CM P- o i ° 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 34 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 t 1 1 1 1 1 1 1 1 1 i i i i l i i i i i i i l i i i i i i i l i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i l l i l i i i i • l I i i i i i i i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 • 1 1 1 1 1 G G i 1 G © . G x> b rt © 1 G ^ tH Sh © > o 1 a _o *H c3 © u C H TJ • rH tu c3 > X3 > w OO co Tf Tf CM CM £ o GO © © CM CM • O ref rH 05 o -P CO CO 05 rH © CO ref O CO © — — — — (h Tf CO CM 40 40 rH CO o CM CO rH 05 o o CO CO CO rH 40 o CO ref Tf rH 40 CO CM ^f OO CM d Tf rH co © 40 CM 05 05 oo 05 CO 05 rH G 40 P- CO Tf G — *. - — ref CO rH »o GO Tf rH »o n 40 rH Tf 05 CO »o CO O rH CM 40 ref CM th CO . -ef 05 rH d H3 CO rH 40 © O O 05 05 oo (h CM cO Tf rH CO »o ref CO CO CM © •ef Tf O 40 CO rH Tf 05 05 05 oo 05 »o CM rH Tf CQ CO ref rH rH CM 05 -ef cdo d CO rH Tf CO P* OO 1 CM 05 CO CM ‘O CO rH 40 O -ef co CO tH •• — — — © ref 40 05 »o -4-3 G £ CM CO t— 40 05 Tf CM 40 O rH CM 05 ref P— rH OO & CO rH 05 o O CM CO »o CO OO 05 p^ o »a P- rH 05 Tf P- CO CO o CO P- OO CO © CM rG 40 | 40 CO 05 CM 40 »o P'— rH 05 © ref •ef O rH rH < CO Tf 00 CM CM 40 *ef OO 05 »o 40 rH rH CO 05 ref CO CO CM © CM O Pt 00 !h rH CO | CO 05 CM o CO 40 CO rH OO o 40 -ef CO rH p- »o fn © CM P- Tf H-3 CM CO 05 40 G P^ 40 CM rH Tf Es o ref rH CO !>• & CM 40 CO O P^ rH 05 05 OO *o 40 Tf rH CO CM ref O rH rH -4-3 — G rH CO co 05 -4-3 CM O CM 05 n Tj CO 40 05 rH rH 05 ref P- CO Tf Et rH lO P- o 05 O 05 05 40 CO -ef CO rH ref ref 00 rH 05 40 rf 40 40 Tf a o oo O 05 05 o o ref O rH H CM Hf Tf CO o G Tf »o > © o l^- O 05 05 H o ref O rH rH CM Tf CM rH CO tH © Tf Tf 43 c3 > i 1 1 1 1 i 1 1 1 1 if i 1 1 1 1 o i 1 1 1 1 1-1 i i 1 1 1 1 1 1 1 1 rH i 1 1 1 1 o 05 rH 1 1 1 1 1 1 • i i i i i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 < 1 1 1 1 1 1 1 1 1 1 1 1 1 40 i i i i i i i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 OO i 1 1 1 1 *""1 i I 1 1 1 a i 1 1 1 1 o i 1 1 1 1 d I 1 1 G I -1-3 m 34 1 1 1 1 G G i 1 o G © . G 35 b a3 © 1 G oj f- CO rH rH G (h © > o 1 a _o --3 Si G "g -*p o O x\ G > © i. G H -4-> G TJ a> ci >3= m £ W OO 325 APPENDIX “B.” TABLE NO. B-3—ILLINOIS RIVER—STORAGE ABOVE BANK FULL STAGE. From Station 15 to Station 201. Eleva¬ tion Station 15-50. Length 35,000 ft. Station 50-80. Length 30,000 ft. Station 80-124. Length 44,000 ft. Station 124-171. Length 47,000 ft. Station 171-201. Length 30,000 ft. center reach. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. 421 1,124 688 422 1,546 2,670 756 1,444 423 2,262 4,932 853 2,297 1,242 424 2^627 7,559 1,331 3,628 1,296 2,538 425 3 j 395 10,954 1,783 5,411 1,376 3,914 426 4,802 15,756 2,832 8,243 1,356 1,590 5,504 855 427 4,901 20,657 3,603 11,846 1,576 2,926 1,941 7,445 883 1,738 428 5,177 25,834 4,277 16,123 1,741 4,667 2,387 9,832 889 2,627 429 5,496 31,330 4,576 20,699 2,049 6,716 2,819 12,651 964 3,591 430 5,720 37,050 4,884 25,583 2,164 8,880 3,049 15,700 965 4,556 431 6,020 43,070 5,246 30,829 2,323 11,203 3,727 19,427 1,083 5,639 432 7,325 50,395 5,333 36,162 2,413 13,616 4,130 23,557 1,242 6,881 433 6,349 56,744 5,405 41,567 2,454 16,070 4,418 27,975 1,282 8,163 434 6,448 63,192 5,478 47,045 2,498 18,568 4,579 32,554 1,533 9,696 435 6,500 69,692 5,547 52,592 2,516 21,084 4,665 37,219 1,567 11,263 436 6,534 76,226 5,603 58,195 2,531 23,615 4,744 41,963 1,581 12,844 437 6,534 82,760 5,652 63,847 2,542 26,157 4,812 46,775 1,599 14,443 438 6,534 82,294 5,651 69,498 2,547 28.704 4,881 51,656 1,613 16,056 439 6,534 95,828 5,652 75,150 2,548 31,252 4,968 56,624 1,631 17,687 440 6,534 102,362 5,651 80,801 2,548 33,800 5,058 61,682 1,644 19,331 441 5,652 86,453 2,549 36,349 5,059 66,741 1,667 20,998 442 2,048 38,397 5,057 71,798 1,666 22,664 443 3,049 41,446 5,058 76,856 1,667 24,331 444 5,058 81,914 1,667 25,998 445 1'666 27,664 TABLE NO. B-3—Continued. From Station 201 to Station 354 Eleva¬ tion Station 201-227. Length 26,000 ft. Station 227-264. Length 37,000 ft. Station 264-299. Length 35,000 ft. Station 299-335. Length 36,000 ft. Station 335-354. Length 19,000 ft. center reach. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. 426 741 427 770 1,511 908 428 801 2,312 948 1,856 429 833 3,145 992 2,848 806 430 868 4,013 1,028 3,876 833 1,639 431 967 4,980 1,085 4;961 869 2,508 806 427 432 1,032 6,012 1,214 6,175 906 3,414 888 1,694 433 860 433 1,150 7,162 1,386 7,561 940 4,354 914 2,608 453 1,313 434 1,313 8,475 1,553 9,114 971 5,325 992 3,600 478 1,791 435 1,427 9,902 1,693 10,807 1,129 6,454 1,056 4,656 502 2,293 436 1,484 11,386 1,734 12,541 1,297 7,751 1,271 5,927 526 2,819 437 1,531 12,917 1,909 14,450 1,349 9,100 1,585 7,512 558 3,377 438 1,585 14,502 1,980 16,430 1,360 10,460 1,775 9,287 566 3,943 439 1,633 16,135 2,052 18,482 1,393 11,853 1,840 11,127 579 4,522 440 1,678 17,813 2,120 20,602 1,414 13,267 1,903 13,030 582 5,104 441 1,723 19,536 2,179 22,781 1,446 14,713 2,191 15,221 610 5,714 442 1,738 21,274 2,211 24,992 1,464 16,177 1,769 16,990 626 6,340 443 1,738 23,012 2,241 27,233 1,492 17,669 2,030 19,020 642 6,982 444 1,738 24,750 2,291 29,524 1,516 19,185 2,050 21,070 658 7,640 445 1,738 26,488 2,292 31,816 1,541 20,726 2,058 23,128 677 8,317 446 1,738 28,226 2,292 34,108 1,557 22,283 2,074 25,202 676 8,993 447 1,738 29,964 2,291 36,399 1,557 23,840 2,075 27,277 677 9,670 448 2,292 38,691 1,557 25,397 2,077 29,354 678 10,348 449 2,292 40,983 1,557 26,954 2,076 31,430 678 11,026 450 1,557 28,511 2,077 33,507 678 11,704 451 1,557 30,068 2,077 35,584 678 12,382 452 678 13,090 326 FLOOD CONTROL REPORT TABLE NO. B-3—Continued. * From Station 354 to Station 442. Eleva¬ tion Station 354-376. Length 22,000 ft. Station 376-397. Length 21,000 ft. Station 397-414. Length 17,000 ft. Station 414-425. Length 11,000 ft. Station 425-442. Length 17,000 ft. center reach. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. 431 1,307 5,888 432 822 2,129 2,127 8,015 433 876 3,005 2,325 10,340 434 905 3,910 2,491 12,831 2,278 435 1,083 4,993 2,545 15,376 2,406 4,684 587 288 436 1,138 6,131 2,661 18,037 2,643 7,327 684 1,271 307 595 437 1,268 7,399 2,836 20,873 2,815 10,142 759 2,030 345 940 438 1,430 8,829 2,890 23,763 3,093 13,235 816 2,846 435 1,375 439 1,526 10,355 2,931 26,694 3,208 16,443 875 3,721 453 1,828 440 1,592 11,947 2,974 29,668 3,314 19,757 934 4,655 490 2,318 441 1,600 13,547 3,050 32,718 3,429 23,186 953 5,608 495 2,813 442 1,606 15,153 3,130 35,848 3,541 26,727 902 6,510 495 3,308 443 1,608 16,761 3,161 39,009 3,586 30,313 970 7,480 495 3,803 444 1,609 18,370 3,164 42,173 3,588 33,901 973 8,453 495 4,298 445 1,614 19,984 3,168 45,341 3,589 37,490 974 9,427 496 4,794 446 1,617 21,601 3,172 48,513 3,589 41,079 975 10,402 495 5,289 447 1,620 23,221 3,178 51,691 3,589 44,668 978 11,380 495 5,784 448 1,623 24,844 3,183 54,874 3,589 48,257 980 12,360 495 6,279 449 1,627 26,471 3,186 58,060 3,589 51,846 981 13,341 495 6,774 450 1,627 28,098 3,188 61,248 3,589 55,435 982 14,323 495 7,269 451 1,626 29,724 3,187 64,435 3,589 59,024 984 15,307 496 7,765 452 1,627 31,351 3,188 67,623 3,589 62,613 985 16,292 495 8,260 453 1,627 32,978 3,187 70,810 3,589 66,202 984 17,276 495 8,755 454 1,626 34,604 3,188 73,998 3,511 69,713 985 18,261 495 9,250 455 3,187 77,185 3,667 73,380 984 19,245 495 9,745 456 3,188 80,373 3,589 76,969 985 20,230 495 10,240 457 495 10,736 / TABLE NO. B-3—Continued. From Station 442 to Station 526. Eleva¬ tion Station 442-452. Length 10,000 ft. Station 452-462. Length 10,000 ft. Station 462-469. Length 7,000 ft. Station 469-493. Length 24,000 ft. Station 493-526. Length 33,000 ft. center reach. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. 435 1,809 436 234 221 2,930 4,739 1,840 437 247 481 308 529 171 3,440 8,179 3,197 5,037 438 265 746 317 846 187 358 3,574 11,753 4,873 9,910 439 310 1,056 354 1,200 238 596 3,828 15,581 6,760 16,670 440 341 1,397 390 1,590 281 877 4,082 19,663 9,702 26,372 441 386 1,783 411 2,001 303 1,180 4,526 24,189 10,411 36,783 442 387 2,170 412 2,413 302 1,482 4,597 28,786 12,877 49,660 443 387 2,557 416 2,829 303 1,785 4,674 33,460 13,292 62,952 444 386 2,943 416 3,245 303 2,088 4,748 38,208 13,729 76,681 445 387 3,330 417 3,662 302 2,390 4,789 42,997 13.875 90,556 446 387 3,717 417 4,079 303 2,693 5,367 48,364 14,276 104,832 447 386 4,103 417 4,496 302 2,995 5,436 53,800 14,525 119,357 448 387 4,490 418 4,914 303 3,298 5,481 59,281 14,742 134,099 449 387 4,877 417 5,331 302 3,600 5,501 64,782 14,830 148,929 450 387 5,264 417 5,748 303 3,903 5,546 70,328 14,919 163,848 451 386 5,650 417 6,165 303 4,206 5,605 75,933 15.009 178,857 452 387 6,037 417 6,582 302 4,508 5,595 81,528 15,014 193,871 453 387 6,424 418 7,000 303 4,811 5,604 87,132 14.877 208,748 454 386 6,810 417 7,417 302 5,113 5,606 92,738 15,411 224,159 455 387 7,197 417 7,834 303 5,416 5,606 98,344 15,272 239,431 456 387 7,584 417 8,251 302 5,718 5,606 103,950 15,273 254,704 457 387 7,971 418 8,669 303 6,021 5,606 109,556 15,274 269,978 458 386 8,357 417 9,086 303 6,324 5,606 115,162 15,272 285,250 459 302 6,626 5,606 120,768 15,272 300,522 460 15,273 315,795 327 APPENDIX “B.” TABLE NO. B-3—Continued From Station 523 to Station 630. Station 526-542. Station 542-572. Station 572-590. Station 590-613. Station 613-630. tion Length 16,000 ft. Length 30,000 ft. Length 18,000 ft. Length 23,000 ft. Length 17,000 ft. center reach. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. 436 738 1,911 437 1,226 1,964 2,641 4,552 1,133 438 1*662 3*626 3,296 7,848 1,376 2,509 940 439 2,062 5,688 3,808 11*656 1,589 4,098 • 623 1,563 360 440 3,471 9,159 4,227 15,883 3,007 7,105 1,903 3,466 360 720 441 3,762 12,921 4,659 20,532 3,421 10,526 2,981 6,447 489 1,209 442 5,227 18,148 4,771 25,303 3,726 14,252 3,276 9,723 678 1,887 443 5,437 23,585 5,248 30,551 4,020 18,272 3,567 13,290 807 2,694 444 6,106 29,691 5,456 36,007 4,296 22,568 3,667 16,957 843 3,537 445 6,277 35,968 5,730 41,737 4,504 27,072 3,669 20,626 859 4,396 446 6,688 42,656 6,300 48,037 4,972 32,044 3,670 24,296 859 5,255 447 6,696 49,352 6,383 54,420 4,977 37,021 3,672 27,968 862 6,117 448 6,702 56,054 6,425 60,845 4,981 42,002 3,672 31,640 863 6,980 449 6,712 62,766 6,621 67,466 4,986 46,988 3,673 35,313 865 7,845 450 6,718 69,484 6,682 74,148 4,990 51,978 3,675 38,988 867 8,712 451 6,727 76,211 6,770 80,918 4,993 56,971 3,674 42,662 869 9,581 452 6,734 82,945 6,820 87,738 4,998 61,969 3,678 46,340 871 10,452 453 6,741 89,686 6,884 94,622 5,003 66,972 3,677 50,017 873 11,325 454 6,749 96,435 6,951 101,573 5,009 71,981 3,678 53,695 873 12,198 455 6,749 103,184 6,951 108,524 5,008 76,989 3,680 57,375 876 13,074 456 6,749 109,933 6,951 115,475 5,008 81,997 3,680 61,055 877 13,951 457 6,748 116,681 6,951 122,426 5,009 87,006 3,680 64,735 876 14,827 458 6,749 123,430 6,951 129,377 5,008 92,014 3,681 68,416 877 15,704 459 6,749 130,179 6,951 136,328 5,008 97,022 3,680 72,096 876 16,580 460 3,680 75,776 876 17,45 TABLE NO. B-3—Continued. From Station 630 to Station 760. Eleva¬ tion Station 630-655. Length 25,000 ft. Station 655-684. Length 29,000 ft. Station 684-707. Length 23,000 ft. Station 707-722. Length 22,000 ft. Station 722-760. Length 31.000 ft. center reach. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. 439 673 3,805 440 573 1,246 2,093 5,898 1,277 441 1,070 870 2,116 2,589 8,487 1,985 3,262 442 1,079 2,149 936 3,052 3,102 11,589 3,574 6,836 406 443 1,085 3,234 973 4,025 3,426 15,015 3,813 10,649 421 827 444 1,099 4,333 1,004 5,029 3,482 18,497 4,018 14,667 484 1,311 445 1,110 5,443 1,076 6,105 3,618 22,115 4,159 18,826 626 1,937 446 1,117 6,560 1,083 7,188 3,649 25,764 4,264 23,090 829 2,766 447 1,122 7,682 1,093 8,281 3,675 29,439 4,300 27,390 939 3,705 448 1,122 8,804 1,104 9,385 3,699 33,138 4,334 31,724 954 4,659 449 1,127 9,931 1,116 10,501 3,723 36,861 4,374 36,098 953 5,612 450 1,128 11,059 1,124 11,625 3,750 40,611 4,410 40,508 954 6,566 451 1,128 12,187 1,131 12,756 3,781 44,392 4,445 44,953 953 7,519 452 1,136 13,323 1,131 13,887 3,818 48,210 4,482 49,435 954 8,473 453 1,139 14,462 1,131 .15,018 3,833 52,043 4,521 53,956 954 9,427 454 1,142 15,604 1,131 16,149 3,834 55,877 4,556 58,512 953 10,380 455 1,148 16,752 1,131 17,280 3,834 59,711 4,597 63,109 954 11,334 456 1,148 17,900 1,131 18,411 3,834 63,545 4,629 67,738 953 12,287 457 1,148 19,048 1,131 19,542 3,834 67,379 4,654 72,392 954 13,241 458 1,148 20,196 1,131 20,673 3,833 71,212 4,654 77,046 953 14,194 459 1,147 21,343 1,131 21,804 3,834 75,046 4,654 81,700 954 15,148 460 1,148 22,491 1,131 22,935 3,834 78,880 4,654 86,354 953 16,101 461 1,131 24,066 3,834 82,714 4 654 91,008 954 17,055 462 4,654 95,662 953 18,008 463 954 18,962 328 FLOOD CONTROL REPORT. TABLE NO. B-3—Continued. From Station 760 to Station 84?. Eleva¬ tion Station 760-781. Length 21,000 ft. Station 781-790. Length 9,000 ft. Station 790-807. Length 17,000 ft. Station 807-820. Length 13,000 ft. Station 820-848. Length 28,000 ft. center reach. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. 441 332 242 558 656 442 338 670 199 441 557 1,115 795 1,451 443 354 1,024 205 646 291 574 1,689 816 2,267 444 378 1,402 255 901 305 596 755 2,444 1,104 3,371 445 491 1,893 350 1,251 319 915 899 3,343 1,273 4,644 446 682 2,575 470 1,721 348 1,263 925 4,268 1,698 6,342 447 884 3,459 541 2,262 386 1,649 952 5,225 2,091 8,433 448 931 4,390 551 2,813 398 2,047 995 6,220 2,931 11,364 449 947 5,337 558 3,371 410 2,457 994 7,214 3,347 14,711 450 966 6,303 569 3,940 416 2,873 997 8,211 3,770 18,481 451 973 7,276 575 4,515 416 3,289 998 9,209 3,944 22,425 452 975 8,251 577 5,092 415 3,704 1,001 10,210 4,053 26,478 453 975 9,226 579 5,671 416 4,120 1,002 11,212 4,156 30,634 454 976 10,202 581 6,252 415 4,535 1,004 12,216 4,236 34,870 455 978 11,180 583 6,835 416 4,951 1,007 13,223 4,258 39,128 456 979 12,159 586 7,421 415 5,366 1,007 14,230 4,262 43,390 457 981 13,140 589 8,010 416 5,782 1,006 15,236 4,269 47,659 458 983 14,123 590 8,600 416 6,198 1,007 16,243 4,275 51,934 459 982 15,105 589 9,189 415 6,613 1,006 17,249 4,278 56,212 460 982 16,087 589 9,778 416 7,029 1,007 18,256 4,280 60,492 461 983 17,070 590 10,368 415 7,444 1,006 19,262 4,281 64,773 462 982 18,052 589 10,957 416 7,860 1,007 20,269 4,281 69,054 463 982 19,034 590 11,547 415 8,275 1,006 21,275 4,280 73,334 464 416 8,691 1,007 22,282 4,280 77,614 465 1,006 23,288 4,281 81,895 TABLE NO. B-3—Continued. From Station 84S to Station 961. Eleva¬ tion Station 848-855. Length 7,000 ft. Station 855-879. Length 24,000 ft. Station 879-908. Length 29,000 ft. Station 908-948. Length 40,000 ft. Station 948-961. Length 13,000 ft. center reach. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. 443 1,379 3,611 4,347 260 444 1,514 2,893 3,911 7,522 4,772 9,119 330 590 445 114 1,704 4,597 4,038 11,560 5,355 14,474 429 1,019 446 119 233 1,807 6,404 4,137 15,697 5,568 20,042 486 1,505 447 125 358 1,878 8,282 4,264 19,961 6,402 26,444 509 2,014 448 130 488 1,961 10,243 4,347 24,308 5,497 31,941 525 2,539 449 134 622 2,040 12,283 4,377 28,685 6,218 38,159 531 3,070 450 136 758 2,122 14,405 4,539 33,224 5,372 44,531 539 3,609 451 139 897 2,191 16,596 4,600 37,824 6,541 51,072 539 4,148 452 142 1,039 2,287 18,883 5,618 42,442 6,739 57,811 587 4,735 453 142 1,187 2,2S3 21,166 4,787 47,229 6,933 64,744 582 5,317 454 144 1,325 2,701 23,867 4,908 52,137 7,127 71,871 584 5,901 455 146 1,471 2,708 26,575 5,008 57,145 7,280 79,151 574 6,495 456 148 1,619 2,770 29,345 5,089 62,234 7,395 86,546 576 7,071 457 150 1,769 2,841 32,186 5,155 67,389 7,498 94,044 585 7,656 458 151 1,920 2,928 35,114 5,230 72,617 7,603 101,647 586 8,242 459 151 2,071 3,015 38,129 5,295 77,914 7,696 109,343 585 8,827 460 152 2,223 3,061 41,190 5,350 83,264 7,790 117,133 587 9,414 461 152 2,375 3,100 44,290 5,431 88,695 7,828 124,961 587 10,001 462 151 2,526 3,099 47,389 5,430 94,125 7,827 132,788 588 10,589 463 152 2,678 3,099 50,488 5,430 99,555 7,828 140,616 589 11,178 464 151 2,829 3,100 53,588 5,430 104,985 7,828 148,444 588 11,766 465 152 2,981 3,099 56,687 5,430 110,415 7,827 156,271 589 12,355 466 152 3,133 3,099 59,786 5,430 115,845 7,828 164,099 588 12,943 467 589 13,532 APPENDIX “B.” 329 TABLE NO. B-3—Continued. From Station 961 to Station 1130. Eleva¬ tion center Station 961-1005. Length 44,000 ft. Station 1005-1034. Length 29,000 ft. Station 1034-1069. Length 35,000 ft. Station 1069-1093. Length 24,000 ft. Station 1093-1130. Length 37,000 ft. ieach• Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. 442 1,065 443 1,222 1,680 2,745 444 1,340 2,562 1,859 4,604 445 1'836 4,398 2,363 6,967 2,326 446 2,832 7,230 2,712 9,679 4,646 6,972 3,162 1,476 447 3 j 667 10,897 2,823 12,502 5,018 11,990 3,499 6,661 1,544 3,020 448 4,423 15,320 3,252 15,754 5,502 17,492 4,005 10,666 2,019 5,039 449 4,570 19,890 3,456 19,210 5,841 23,333 4,732 15,398 3,150 8,189 450 5,025 24,915 3,950 23,160 5,318 28,651 5,285 20,683 3,977 12,166 451 5,446 30,361 4,005 27,165 6,984 35,635 5,864 26,547 5,293 17,459 452 5,757 36,118 4,044 31,209 6,305 41,940 6,093 32,640 5,650 23,109 453 5,972 42,090 4,085 35,294 6,364 48,304 8,162 40,802 5,867 28,976 454 6,186 48,276 4,125 39,419 6,408 54,712 4,266 45,068 6,063 35,038 455 6,445 54,721 4,161 43,580 6,412 61,154 6,274 51,342 6,313 41,352 456 6,646 61,367 4,213 47,793 6,464 67,618 6,334 57,676 6,633 47,985 457 6,786 68,153 4,259 52,052 6,496 74,114 6,398 64,074 6,772 54,757 458 6,949 75,102 4,286 56,338 6,518 80,632 6,425 70,499 6,864 61,621 459 7,153 82,255 4,307 60,645 6,608 87,240 6,480 76,979 6,922 68,543 460 7,265 89,520 4,340 64,985 6,506 93,746 6,498 83,477 7,011 75,554 461 7,323 96,843 4,345 69,330 6,585 100,331 6,758 90,235 7,375 82,929 462 7,386 104,229 4,358 73,688 6,591 106,922 6,784 97,019 7,699 90,628 463 7,386 111,615 4,359 78,047 6,591 113,513 6,804 103,823 7,713 98,341 464 7,385 119,000 4,358 82,405 6,591 120,104 6,804 110,627 7,713 106,054 465 7,387 126,387 4,358 86,763 6,596 126,700 6,804 117,431 7,712 113,766 466 7,386 133,773 4,359 91,122 6,586 133,286 6,805 124,236 7,713 121,479 467 7,385 141,158 4,358 95,480 6,592 139,878 6,804 131,040 7,712 129,191 468 6,804 137,844 7,713 136,904 TABLE NO. B-3—Concluded. From Station 1130 to Station 1219. Elevation center reach. Station 1130-1162. Length 32,000 ft. Station 1162-1194. Length 32,000 ft. Station 1194-1219. Length 25,000 ft. Diff. Ac. ft. Diff. Ac. ft. Diff. Ac. ft. 447_ 718 568 448_ 717 1,435 568 1,136 314 449_ 784 2,219 784 1,920 338 652 450_ 1,144 3,363 1,215 3,135 421 1,073 451_ 1,993 5,359 1,438 4,573 599 1,672 452__ 2,760 8,119 1,906 6,479 673 2,345 453__ 2,974 11,093 2,219 8,698 806 3,151 454_ 3,086 14,176 2,477 11,175 894 4,045 455_ 3,251 17,427 2,871 14,046 1,164 5,209 456_ 3,325 20,752 3,019 17,065 1,328 6,537 457____ 3,375 24,127 3,153 20,218 1,594 8,131 458_ 3,440 27,567 3,230 23,448 1,780 9,911 459_ 3,483 31,050 3,440 26,888 1,965 11,876 460__ 3,531 34,581 3,614 30,502 2,237 14,113 461__ 3,581 38,162 3,639 34,141 2,290 16,403 462_____ 3,624 41,786 3,667 37,808 2,398 18,801 463_ 3,670 45,456 3,694 41,502 2,467 21,268 464__ 3,723 49,179 3,715 45,217 2,524 23,792 465... 3,723 52,902 3,715 48,932 2,596 26,388 466.__ 3,723 56,625 3,715 52,647 2,596 28,984 467.... 3,723 60,348 3,714 56,361 2,595 31,579 468__ 3,723 64,071 3,715 60,076 2,596 34,175 469..... 3,723 67,794 3,715 63,791 2,596 36,771 470... 2,596 39,367 330 FLOOD CONTROL REPORT. co KH o £ t—I p p H ^ 4) £ bO ►> TJ ffl Q Pi h-1 Pi « S 'S 5 O c3 rr Q P5 3 • Q< W s «a ^ • S co r P O O £ m P pq m a ^ 2 U © © N o ‘t? 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CO OC CP CP CO t» *0 *0 00 CP CP CPCOCPCfaCMCOiOOOOi-iCOOCO 0 co co rfa CM ’fa ifa CM CM CM ’fa ’fa CM CM CO ’fa rfa t —1 ifa ifa CM »fa cm co n- CM ^ , CM ... . CM .©^^fa^-fa^-* ..©^ ►-. ^ © 0 . G Grt 33^ Jo90 ut)uuu «“ ot ' uo l2^3 mmmmOOOOOOOOOOO §S-i rtNCCViOOhOOCIOii NCOl'iOfflNOOOSO-iNeOl'ifltO NOOOJ 6 r^^^ri^nrtTHCMCMCQCMClCMCM CM CM Ol 55 ote —All current meter measurements were taken at the Havana Highway Bridge. F” indicates falling river, “R” rising river and “S” stationary river. Discharges in table are 90% of observed flow. DISCHARGE MEASUREMENTS OF ILLINOIS RIVER AT BEARDSTOWN, ILLINOIS. Gauge readings refer to gauge on Chicago, Burlington & Quincy Railroad Bridge. Elevation of zero gauge=427.25 Memphis Datum. 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CM CM . CM . CM . CM. o • rp • • oirsrs k. k. oj.hO.h . H b b b s???" b t ^ fc:p**-* a’ - " a q, a q, & a a a* 3 . ^ Q« Q« P Jjf Pt Q*. P 30 Q« Q« 3 ^ Q 3 < -22 *2 -p -p -P> -22 o o o o o o o o o o o o ■"d T3 "O T3 "d 0 0 0)000 |_ >_ P Li P P ©©©©©© a a a a a a X5X5 32X5X5X5 3 3 3 3 3 3 CQ CD CD GO CD 03 t_l_.tHf-lt-.t-l o o o o o o -43) -4-3 -43) -4-3 -4-3 -4-3 O A) O Q) 0) O -4-3 -4-3 o o o o 73 73 O O fcD bJD t— f- O O a a X5X! 3 3 cn to p p © © ■*2 *2 © 0) §s CVJ CM *4-4 *4-4 *4-4 O O O a c a <3 c3 c3 O O O § g§ OOOOQQ QQQQQQ kkkggkgg r'^r'icccz) p p p p p yy.. MMbDMM QQ^^hhwhw coojy Status of river. fefefefefefe Ph fe ! | P 1 . Ph Ph Ph 1 1 1 1 1 1 1 1 1 1 1 1 1 t ischarges, C.F.S. O CM CO O CM OO lOOOO^NCM iO lO *-» CM OO *0 COOOOOOOtOlNNiO OtOOOtOCOOO-HN O to CO CM y-* O 05 00 05 lO N Tf (N O 00 05NN^ CO^COO t^t^00 00CX)t>-t^C3O3 Q Mean velocity, second- feet. CONO'tOCO iO ^ CO *0 CO CM CM CM CM CM CM C0NOCM00C0O5 00rH CO CO CM CM 05 05 00 CO CM CM CM CM CM CM CM CM CO CO xT . 1 —( lO CM CM O O O 05 CM OO Tf CO t>- to *0 CO CO ^OOOOOCOCOCOCO 0 *—1*00 00 00 00 00 00 to co 0 0 O 0 0 O Widt feet I0t0t0ic»c»0 tO tO ^ ^ 4-H y—f £ COONMC5iO 1 1 Tf CO » 1 CMO 1 ONN Maximui depth, feet. CM CM h h O O CO CO CO CO CO CO 4“H t-H 1 1 03 00 N O *”t COCO • » CM CM CM CO CO 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Area of section, square feet. Tf CO OO ^ OO CO CO 05 ^ fO CO to CO 1-H 00 TJ* 03 0 OO CO to CO CO CO CO CO 03 03 O O CM O 03 CM CO TflNOO-HCOOON 03 tO NCO CM CO CO . 05 rH co CM CM CM r-4 Date. CO CM . ^ -fe> -43> -43) -fe2 4-3 -435 OOOOOO OOOOOO 1927 April April April June May May May June June o QO O O CM CO CO CO TT ^ CO^^tjtOOt^OOC^ o tfl 73 • r -4 &4 « >» d £ 43 M W C & o +2 tn T3 • Pi >j d P © d ca c rr ° 43 rt -3 —2 00 . ri : & C CO o ©; 33 'd"C" d ■2 c® £ 1:8 p is p © g © 2 £ >42 oo‘p ° ■*“ 5 *4-4 c to O © c _ S. 2 ^ 3 = © S3 §-.® 3 p o p £ d © > 42 -4-3 • j-4 PH Ph CO PH O Z PH XI XI PH o co H Z W S M CO < H c o -22 < -8 43 a a © o ^ to o d o- © 43 o C O © to 3 d to o H-2 p © PH © P m to fl © bt 3 d to O p © N Mh O C o > pH -*X> c3 > o 73 H O t-. H O »t>-r>- 05Or4(^C0TM0C0N00 rH!NMN(N(N(NN0000Q>000 G>Q>a>Q)G)Q)Q)00 MMMMMMMMMMMfcBMMWIMMMMbfl t—I (—" t—< t— *—' t—I I—i ^—i I—' ^— t—■ t—■ t—i t—' •—i t—• f—< t—> P—< t—< OOOOOOOOOOOOOOOOOOOO ssasssssssssssssssss X>X2£2X!J3X2X2£>£1X2£>X}£!X)S>£1£)X2JDJ3 33333333 333333333333 OQGQGGGGGQGQGGGQGQOQOQGQOQGQGftGGGGGGOQGQ OOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOO §§§§ggg§g§gggggsg§§s #*■*■*■**■*■*■*••*■*****■*•*■*** oooooooooooooooooooo QQQQQQQQQ QQ Q Q QQQQQQ 6 i_i (_■ o o o o o o MM o o o o o o hhs f-.* ^ t- ^ t- g? ^ u ^ tJ ..^bD^tJDOfc^ObjDObJD^bC COCC ^C^Cst3^C^CiS3 >- l >-> 3 3 3 3 3 3 o o o o o o NCOrHOrfOOCOCOOlCCOOOCJCOINOO 05rf<05»0^NOXiC(MO»HC0(MC0C0iC OHNlOlOTfOrHCO-HCOOOOOJHC^ lO'fNiOCOWCCNOOiCNOS'^CONNO OOCONNNNNNNNNOOOCOOOOGO O CM CO o o o o o o O CO o O OO to to o o CO o Tf NN >COh CM CO CO to CM lO^Tf WOrH to to OO OO OO y ~~ l T ~~ l GO 05 05 CO 00 to NNOC50(NiCN'M»flNH050(NW030iOM r^COTPTt-COlNCOCO^COTMONNOJOSOOOiOlO cococococococococococoeocococococococoTt* (N(N^OOOOOOO«OOMCOOOOOOOCO(X)T}i CDOCOCONNNNNNCOOCOCCOCOCDCDN OOOOOOOOOOOOOOOOOOOO «OC5NN05h^iC»OhOhhOOOON^hN TjHTjnONNOOCOOOOOOOOOOOOCOOCONNNNO CMCMCMCMCMCMCMCMCMCMCMCMCMCMCMCMCMCMCMCM MOOlOOHOiOOJOfOOHWNOiOOO’tW Nhicwi0O(NNCC»0OO^WCC^05t-.NN NOWO(NiC0005TjiTjuc^T}iTf(N'-iCDTfO OOOiCT>^(NCVJ(MCl(M(MCONOOQO'-(NCC’r‘CONa >co^ CM CO I H H f-CM t^. •p -p. 05 Q. Q,-*-5 -5 -*-5 -«-5 -4-5 -«-5 -*e» *“ H ojccOOOOOOOOOOOOOOOOOO a cs cl *H kfH ^ < oo CO CO CO o CM r—1 r —1 CO April >t c3 >t a w-t o G P 3 3 3 <5 ^5 o tti G w 33 3 o H 3 PS a o < •8 o M 3 • O >i J2 3 U § ©•a 5 * ^ -»j -w QQ 3 - eco OJ - 333 3 U) 3 >3 (, >33 rn’E-r) Mg c > f. E "E £‘ C J3 3 : o <2Crf«« 8 : ® a eg c3 o 2 m G ® >A C +a” c3 *— r " ffl § w • ■5 go o 8^ o o ^ > ® CCCiOOO^iOlN^TfOOfOiNfCCOlb^tNrf^OOiO OOXNXCCC^N^ONr. OCCbDC^MCCJOCO WfNMMeocowwwMMtNcqcoTjiW^ecccc^fMcq -»-3 -4^> o .z, © c ^ +* .sag * pci o c g-2 j- o <- ° ’ 0Q • © © O’ CD CO ^ lO N O O ic M ’W' 'w IT N-Tj-CNOOCrJ'O OCC^NCCCOON^CCTj'TrCTfC'.TrOCC OCCC:wiOTrNib^:NNXNC5WNNC5NOOC:« OOtOOCC;(N(N^(N(N^OC:'wC^MOCiaNC CMCMCMCMCMrccccocccoc'crccMCMCMCMCMCM^—i’—' - < 3 > cn ^2 © © © U5 iO C X ib « lOiOCOONNi :OibrrOMXX(N(NXCXOXO (^(N^LbOO— TfN^rj-XNOCCC ^WM , TfibN»XXNN©©Tt'rbCQ’-<©OC'.OON cowcocbccrcbbcbcccccbcc^cbcbcccccciNbKNW ^ Tj' ^ Tf ^ Tj" TT 1 ^ Tf 1 Tf" Tj* Tj' ^ TT Tf T}* TJ* © to SP.S*: O o 8- u icioibCxiocoLbTfONXxiNtNacxcxo XXCOdOC'tOibfNX’-'TrNOTTN'-'CXCCO eorcTf'i^cooooxx«Nt>«©'^'^Mi •»-CCi«N © a OOCSOrt'NTnOONOO©’ (N!N W Tf XOiCNQ- — CM CM CM CM i • coico CO CM . . . © +i 4^ -P.. ' cv rv Q, > > > o o o oooo&tzzz o 2 ; INM^IOCDNXCJC' •CMW^iOCNOOOC^bl I 1H »-( iH rH r-l y—1 y—i CM CM CM Note— Current meter measurements taken 1,200 feet north of ferry landing. “F” indicates falling river, “R” rising river and “S” stationary. DISCHARGE MEASUREMENTS OF ILLINOIS RIVER AT REICH’S FERRY. (Mile 83.9 from mouth of river.) Gauge readings refer to temporary gauge at Reich’s Ferry Landing. Elevation of zero gauge=434.15 Memphis Datum. 341 APPENDIX “B.” M Cl Cl C-< C Tf O WO MrHCOOrHQO COCO OCOOOONNO ^C^CTiOCOCt^- NCOCcOCOr-• CO CO CO CO CO CO o »o o »o »o OOOONiOrt. O 03 C3 O O'. C5 o o o o o o O CO OO CO CM I CO (N rH rH H CO CO CO CO CO CO CO CO ’— 1 CO CM r-H CDNO'tC-lOO !>• CM CO O O LO (N (N rH rH - Cl Cl Cl (N (N Cl OOONMW OCGOiOfNO ■^■^COCOCOCl OO O Cl CC lO *-• CM CM CM CM Ol CO CM o* . a a a a a a O ^ *■< .2 u> o fi es "c **"' jr (> ef Csaatrc/ date M a y A f* _ job no. J 66 rt£A1P///S Z?A TO /~? APPENDIX “B.” 361 362 FLOOD CONTROL REPORT 1 cre feer JOB. Xl/inof3 /Bi/C/- /7 qo«/ Gant ry/ DATE_ /V0 Y'i /L job no. <3 6 6 APPENDIX 363 “b.” - 774/9 0 / 5 M>f. f/aoJ Conifo f DATE- S/Q* M.&iL p?? /Ac/?e ff£r MS/'IMtJ 0Arc//»? 364 FLOOD CONTROL REPORT JOB. tV 6, _ Z _ * 1 j | " V z j V A z Cr Q-JL . -4i96 * — r-^ A z z 7* la [Z 9J ~ ^ : Lj 20 fs "*** w N. ^v. *>»-■ - — H “1 _ -- ■Us . A . V" ST lZ X* ' V p L & JL Ft _ _ zi A — ' r— — — i=» - Z 1 -4 - — | - — -3? = B.-r. f. £■ L Z 1 _ z ea~ ii [Z -- - — z L \ z /gh - T A 1 LZ j , Jr I n ' — / t S> r z I s >— Ui "V J Sr r z zz f s t Sr ■C?JS /s 9 _ L _ — _ _ _ - _ ; _ _ — V _ A _ p- *4 Z — — — — — — — — — — — - — — — — — — — — — — JZ< - P 4 ( JL. ZB _ — 8 ^ 1 “N 1 - ^ S - / 7 hk V I 7 • A / ■v \± _ — L _ _ _ - - — — — A Sv z h _ A y 7a ya < — — — P ~.o -c er a « x? . Z A z 1 z \i£. Z L I t 1 1 IT V 1 — _ z i / — \ tz _ • — K Z /V- ZFZ&. L z Z _ ZL 5,, Z □l J — — >— - — ■* ' _ TZ * tl _ tz ■ ■: JT 9 4 t&LZ 225* f \ r z z ! — > r,i Tv - - > _ i /I \ BE Tj _ — , J f Z > 1 LZ ' — " W, Tj . _ tr _ p V LZ L_ “r z 1 | z — — z ■2 f V U JZ _ \ Z J S lJ s r I h — 1 _ \ / L V— z TEC ’ v\ — / 1 1- A N. z — nr Z _ f [“ _ ~ z 1 : = — 1 — — — Li _ LI - - - _ - - . I _ _ L _ _ _ 1 1 La TS- O • l£1 lAZ a 2 EB 373 APPENDIX “B.” HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1898 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer F IGURE B 19 374 FLOOD CONTROL REPORT. HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1899 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer FIGURE B 20 375 APPENDIX “B.” HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1900 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT or 1928 F IGURE B2 I 376 FLOOD CONTROL REPORT. HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1901 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer FIGURE: B22 377 APPENDIX “B.” HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1902 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer R E PORT OF 1928 FIGURE B 23 378 FLOOD CONTROL REPORT. HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1903 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT OF 1928 FIGURE B24 379 APPENDIX “B.” HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1904 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting- Engineer FIGURE B25 380 FLOOD CONTROL REPORT. HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1905 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer F IGU RE B26 381 APPENDIX “B.” HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1906 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT OF 1928 FIGURE B27 382 FLOOD CONTROL REPORT. HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1907 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT OF 1926 FIGURE BZ8 383 APPENDIX “B.” HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1908 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer FIGURE B29 384 FLOOD CONTROL REPORT. HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1909 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer FIGURE B 30 APPENDIX “B ” 385 HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1910 ' REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer FIGURE B 31 —25 F C 386 FLOOD CONTROL REPORT. HYDROGRAPH OF DAILY RIVER STAGES • Illinois River 1911 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT OF 1928 FIGURE B 32 387 JUNE JULY MAR APPENDIX “b ” HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1912 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer FEB. 10 20 JAN. 10 20 REPORT OF 1928 FIGURE B33 388 FLOOD CONTROL REPORT. HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1913 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer FIGURE B 34- 389 APPENDIX “B.” HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1914 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT OF 1928 FIGURE B 35 390 FLOOD CONTROL REPORT. HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1915 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer JUNE! JULY MAR APR MAY fAKAJl* FIGURE B 36 391 APPENDIX “B.” HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1916 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer FIGURE 337 392 FLOOD CONTEOL EEPOBT. HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1917 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer FIGURE B38 393 APPENDIX “B.” HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1918 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT OF 1928 FIGURE B39 394 . FLOOD CONTROL REPORT HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1919 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer FIGURE B 40 395 APPENDIX “B.” HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1920 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer FIGURE B 4 I 396 FLOOD CONTROL REPORT. HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1921 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT OF 1928 FIGURE B42 397 Boards to w/v ■4/0.94/V.D. APPENDIX “B.” HYDROGRAPH OP DAILY RIVER STAGES Illinois River 1922 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT OF 1928 DEC sept: OCT NOV 10 20 AUG FEB MAR JUNE JULY 10 20 APR MAY 10 20 10 20 10 20 10 20 10 20 FIGURE B 43 398 FLOOD CONTROL REPORT. HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1923 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT OF 1928 FIGURE: B44 399 APPENDIX “B.” HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1924 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer JUNE JULY MAR MAY S,7/:aA REPORT OF 1928 FIGURE B 45 400 FLOOD CONTROL REPORT. HYDROGRAPH OF DAILY RIVER STAGES Illinois River 1925 REPORT ON FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT OF 1928 FIGURE! B 46 401 APPENDIX “B.” HYDROGRAPH OP" DAIRY RIVER STAGES Illinois River 1926 REPORT ON FROOD CONTROR OF THE IEEINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer 2(j F C FIGURE B 47 402 FLOOD CONTROL REPORT. HYDROGRAPH OF DAILY' RIVER STAGES Illinois River 1927 REPORT OX FLOOD CONTROL OF THE ILLINOIS RIVER DIVISION OF WATERWAYS, STATE OF ILLINOIS By Jacob A. Harman, Consulting Engineer REPORT OF 1928 flGUREl 3 48