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 TRANSMITTING 
 
 The prelimlnary report of the Mississippi Hirer Commission. 
 
 March 10, 1880.—Referred to tlie Committee on Commerce and ordered to be printed. 
 
 War Department, 
 Washington City , March 10, 1880. 
 
 The Secretary of War has the honor to transmit to Congress, in com¬ 
 pliance with the provisions of the act approved June 28, 1879 (chap. 43, 
 Aimphlet Laws, page 38), a preliminary or partial report of the Mis¬ 
 sissippi Eiver Commission, with the papers accompanying the same; 
 also a minority report of two members of the Commission. 
 
 Eespectfully submitted. 
 
 ALEK. EAMSEY, 
 
 Secretary of War. 
 
 The Speaker 
 
 of the House of Representatives. 
 
 Tiie Mississippi Eiver Commission, 
 
 President’s Office, Army Building, 
 
 33 West Houston Street, 
 
 Kew Yorlc , March 6 , 1880. 
 
 Sir: I have the honor to transmit herewith a preliminary or prartial 
 •eport of the Mississippi Eiver Commission. It is expected that the two 
 uembers of the Commission—Geueral Comstock and Mr. Harrison—who 
 lave withheld their signatures from the report will submit separate 
 tatements, embodying individual dissenting opinions, upon the several 
 ubjects discussed therein. When these are received they will be for¬ 
 warded without delay, in order that they may take their appropriate 
 lace as appendices to the report. 
 
 The following papers are hereunto appended, viz.: 
 
 I 1. A financial statement made by Lieut. Smith S. Leach, Corps of En- 
 Lueers, the disbursing officer of the Commission, showing the disburse- 
 
REPORT OF MISSISSIPPI RIVER COMMISSION. 
 
 meuts made and liabilities incurred to February 1G, 1880. It will be ' 
 seen from the statement that the whole amount appropriated will be 
 expended by the close of the current fiscal year in making the surveys . 
 and examinations deemed requisite by the Commission. 
 
 2. A Coast Survey chart of the “Mississippi River from the Passes to • 
 Grand Prairie, Louisiana,?’ 
 
 It is understood from the superintendent of the Coast and Geodetic 
 Survey that the engraved plate of this chart will be placed at the dis¬ 
 posal of the Public Printer, so that its reproduction will be unnecessary A 
 Very respectfully, vour obedient servant, 
 
 Q. A. GILLMORE, 
 
 Lieutenant-Colonel of Engineers, Bt. Maj. Gen., U. S. A., 
 
 President Mississippi Elver Commission. 
 
 Hon. Alexander Ramsey, 
 
 {Secretary of War, Washington , 1). C. 
 
 [Indorsement.] 
 
 Office Chief of Engineers, U. S. Army, 
 
 March 8, 1880. 
 
 Respectfully forwarded to the honorable the Secretary of War. 
 
 II. G. WRIGHT, 
 
 Chief of Engineers, Brig. & B-v't Maj. Gen. 
 
 REPORT. 
 
 Washington, D. C., February 17, 1880. 
 
 Sir: The Mississippi River Commission, constituted under an act of 1 
 Congress approved June 28, 1870, respectfully submit the following 
 partial report: 
 
 The work assigned to the Commission was— 
 
 First. To direct and complete such surveys of the Mississippi River 
 between the Head of the Passes, near its mouth and its headwaters, as 
 were then in progress; and to make such additional surveys and ex¬ 
 aminations of said river and its tributaries as might by it be deemed 
 necessary. 
 
 Second. To take into consideration and mature such plan or plans as 
 will correct, permanently locate, and deepen the channel, and protect 
 the banks of the Mississippi River; improve and give safety and ease 
 to the navigation thereof; prevent destructive floods, and promote and 
 facilitate commerce and the postal service; and with such plans to pre¬ 
 pare and submit estimates of the cost of executing the work. 
 
 Third. To report specifically upon the practicability, feasibility, and 
 probable cost of the plans known as the jetty system, the levee system, 
 and the outlet system. 
 
 By section 5 of the act authority was given to the Commission, prior ] 
 to the completion of all the surveys and examinations, to prepare and 
 submit plans and estimates of cost for such immediate works as in the 
 judgment of the Commission may constitute a part of the general system 
 of works contemplated. 
 
 The Commission met for organization in the city of Washington on 
 the 19th day of August, all the members being present, and immediately 
 upon its organization took into consideration the surveys of the river 
 

 REPORT OF MISSISSIPPI RIVER COMMISSION. 3 
 
 ilready u in progress,” and U such additional surveys, examinations , and 
 investigations , topographical , hydrographical , and hydrometrical , v as 
 ‘ciseemed necessary to carry out the objects of the act of Congress estab¬ 
 lishing the Commission. 
 
 al It was found that the portion of the river lying above the mouth of 
 t p<jlie Ohio had been essentially covered by the several shore-line surveys 
 ylMready completed, or drawing to a close, so that the attention of the 
 ^Commission was directed more especially to the lower river between 
 ^t(Oairo and the Head of the Passes. This portion of the river, measuring 
 ibout 1,100 miles along the channel, had been the scene of numerous 
 Jadetached surveys, the data from which will be available notwithstand¬ 
 ing the intervals of time that they cover; and in providing for the con¬ 
 nection and extension of these, the Commission decided to so arrange 
 girlie work of the present fiscal year that the information immediately 
 jWrequired should be obtained by systematic methods, useful not only to 
 jtlihe proximate ends in view, but in connection with the wider range of 
 ■m nquiry that must ultimately be necessary. 
 
 i<; it was considered important that the triangulation, so essential in 
 jthocating the river, however limited the field of practical operations of 
 •tommediate improvement might be, should be so executed and per- 
 ^fnauently marked that it would furnish the basis of future surveys. 
 b( It was therefore decided that a line of secondary triangulation should 
 its triangles closing within G seconds. 
 
 For the present, however, it was deemed desirable to execute no de¬ 
 railed or widely-extended topography, but to develop as rapidly as 
 sljpossible the shore lines and the forms of the liver bed. 
 
 ^ It was furthermore decided that physical inquiries extending to all 
 the recognized phenomena likely to have a bearing upon problems of im- 
 Srovement should be instituted at once, and that they should be based 
 ipon the experience of predecessors who had already made much pro¬ 
 gress in these studies. 
 
 Provision was made for running lines of precise levels along the river 
 auk and for maintaining and increasing the number of the stations at 
 hich the elevations of the river are recorded, so as to trace in future 
 he progress of floods and the larger features of the river slopes, witli- 
 jtl|>ut, it is hoped, any further interruption. 
 
 Provision was also made for physical examinations of selected reaches 
 f the river, distant from each other, but presenting locally and rela- 
 ively the most widely-contrasted elements of width, depth, and curva- 
 
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 ijure;. that the conditions most favorable and those most inimical to 
 pliavigation might thus be traced back to their causes inductively, 
 ol At these early meetings resolutions were adopted embodying the 
 bpense of the Commission as to the extent and character of the surveys 
 equired, and the committee composed of a majority of the members 
 vas appointed to carry out the views thus recorded. 
 
 Inquiries were made of the Secretary of War and of the Secretary 
 t*)f the Treasury as to the aid they could render in these surveys, free of 
 vl^xpense to this Commission, and the committee on surveys was author¬ 
 ized, after the receipt of replies to the above inquiries, to direct the 
 
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 secretary of the Commission to employ the necessary persons, and make 
 lall purchases of instruments, materials, and outfit needed to carry out 
 [the provisions of the resolutions already adopted as to surveys, &c., to 
 >e made at once. 
 
 The surveys thus instituted are being executed under direction of 
 :his Commission in part by its employes and in part by parties and 
 Vessels of the Coast and Geodetic Survey; detailed under section 3 of 
 
1 
 
 REPORT OF MISSISSIPPI RIVER COMMISSION. 
 
 e 
 
 the act; the former moving from Cairo southward, the latter working in 
 
 the lower part of the river. . 1$ 
 
 The continual prevalence of yellow fever at several points on t • 
 
 lower river until late in the fall prevented these parties from beginning 
 
 their work as soon as was expected. 1i7 , 0 
 
 The following estimates of the extent of river completed 01 like y 
 be covered during the present season are based upon the rate ot progress, 
 furnished in the schedule drawn up by the Secretary of the Commission, 
 
 be covered during me preseut aic —y *—~ 0 
 
 furnished in the schedule drawn up by the Secretary of the Commission, 
 and in the report of the Superintendent of the Coast and Geodetic ^ 
 
 ^Gauaes —The gauges along the river between Cairo and New Orleans 
 were increased in number to 20, and more recently others have been 
 added between Cairo and Saint Louis, so that the elevations of the m ei 
 surface are now recorded daily at intervals ot about 50 miles. 
 
 The zeroes of these gauges are to be referred to a common plane of 
 re/erencJ by the lines of precise levels to be described hereafter in the^ 
 
 0rA TrialgllaUon S —0( the 1,100 miles of river lying between Cairo and 
 the Head of the Passes, the triangulation of past years, executed by 1 1 
 oovernmeut, amounted in all to about 407 miles, comprising the progress 
 work of the Coast and Geodetic Survey, as well as the surveys made 
 
 by the United States Corps of Engineers. 
 
 Of the employes of the Commission, three double parties, now m the 
 field are engaged upon triangulation. This work, inclusive of about lb 
 miles previously executed,has already reached Memphis; and,as be ow 
 this point about 85 miles of work previously executed will be met with, 
 it is anticipated that the parties will reach the mouth of \\ hite Pvi\ei, 
 
 420 miles below Cairo, by the 1st of April. 
 
 The trigonometrical points established by these parties are to be r - 
 ferred to permanent marks beyond the erosions ot the river, by the topo- 
 
 frranhical party following them. , 1 
 
 Four single triangulation parties have been placed on the river, under 
 this Commission, by the Superintendent of the Coast and Geodetic Sum 
 vev Mr C P. Patterson; and these have been located by the board 
 with a view to connect the isolated fields of work which now rest upon, 
 
 8e j\lr. Patterson expects, with the appropriation made by Congress for 
 the work under his superintendence, together with an allotment from 
 the funds of this Commission, to execute300 miles ot triangulation dur- 
 iu o’ the present fiscal year, and make the chain of geographical positions 
 fomnlete from the Gulf of Mexico to Providence, about oOO miles. 
 
 As these parties were not to be immediately followed by topo- 
 oranhical surveyors, it was deemed advisable to require ot them the es- 
 fablishment ot reference marks, which has rendered their progress 
 
 slower than it otherwise would have been. . 
 
 At the request of the Commission, the Superintendent of the Coast 
 ami Geodetic Survey has measured a base line in the vicinity ot Cotton 
 wood Point, 120 miles below Cairo, to be used in connection with the 
 
 triangulation executed by t he employes of the board. 
 
 Topography and Hydrography.—These have been combined in the 
 operations of one party, having three divisions, composed ot employe. 
 
 the Commission. One of these divisions develops the shore line o. 
 tlie actual river with its banks, tow-heads, chutes, islands, &e., as wel 
 as levees when not more than a half mile back from tbe water; auot lei 
 follows with levels, giving the elevations of banks, water-surtaces, cross 
 Sons of levees, &c.; while the third division sounds out the bed o 
 
f 
 
 1 
 
 REPORT OF MISSISSIPPI RIVER COMMISSION. 5 
 
 r 
 
 ‘tlib stream in connection with the levelings, so as to complete the normal 
 ,cr)ss-sections of the river and its approaches about every half mile. All 
 itbU work rests upon the preceding triangulation, and the topographers, 
 they pass the triangulation stations, are required to refer them to 
 t p<rmanent marks already mentioned. These marks are placed about 
 .tlree miles apart, measured along the general course of the river, and 
 ^ir pairs on either side, the one nearest the river bank being so placed as 
 be sure to remain undisturbed for at least twenty years. 
 
 , The present work will not furnish a detailed map showing the char¬ 
 ter and elevation of the swamp and bottom lands lying far back from 
 jte actual lines of the river, but the necessity of more elaborate maps as 
 Aticipated, and these marks are to secure the full advantage of all tri- 
 ^igulation executed this season as the basis of future topographical 
 ork wherever the trigonometrical points shall have been obliterated by 
 Je caving of the banks. This combined party, traversing short lines, 
 pleasuring elevations, and sounding out cross-sections, has advanced 
 *0 miles and made connection with the work of examination party in 
 e vicinity of Plum Point. It is anticipated that it will carry its work 
 Memphis during the present season; beyond this, for a distance of 
 j) miles, complete maps exist from the survey made by General Comstock 
 ffore the Commission was created. 
 
 At the time the Commission was organized charts had been published 
 the Coast and Geodetic Survey of the portion of the river lying be- 
 peen Point Houma (about 72 miles above ^few Orleans and the Gulf), 
 lowing depths of water, with marginal topography; so that there re- 
 ained for this Commission to execute, in the river .below Cairo, about 
 )0 miles of surveys of the skeleton form above indicated. 
 
 Precise levels .—Prom employes of the Commission two parties were 
 ^signed to run a line of precise levels, in duplicate, and in opposite 
 irections, with permanent bench-marks every three miles, so located 
 ad marked that they may be relied upon for at least twenty years, 
 he most accurate instruments known to engineers were placed in the 
 ands of these parties, and they were instructed that the discrepancy in 
 uplicate lines of levels should not exceed o mm , x the square root of 
 le distance in kilometers. 
 
 They began their work at Columbus, 20 miles below Cairo, at tho 
 nomination of a series of levels previously executed by General Com- 
 tock, and have advanced to Cottonwood Point, 120 miles below Cairo, 
 'hey will probably reach Memphis by the middle of April, should no in¬ 
 terruption from Hoods occur. Here they will connect again with a series 
 f levels executed by General Comstock which extends about 83 miles 
 jelow. 
 
 It is proposed to put another leveling party into the field as soon as 
 roper instruments are obtained, and if this additional party can pursue 
 ts work until the first of May the precise levels will be brought nearly 
 jo the mouth of White Elver, where the triangulation of this season 
 rill probably terminate, as above stated. 
 
 In the lower portion of the river two parties of the Coast and Geodetic 
 Survey are running similar lines of precise levels between Carrollton 
 ind Greenville, and the superintendent expects to be able to keep this 
 Vork in progress during the entire season and close this space of 500 
 miles by the end of the fiscal year. 
 
 \ Examinations .—Three localities have been selected at which surveys 
 are repeated frequently to ascertain the varyiug relations of the river 
 and its bed ; these are Plum Point and its approaches, Lake Providence 
 and its neighborhood, and Carrollton ; the last named being selected 
 
6 
 
 REPORT OF MISSISSIPPI RIVER COMMISSION. 
 
 because it was the site of similar inquiries during the surveys of Ilnlim 
 phreys and Abbot in 1858. 
 
 The observations at these places comprise tlie changes in the figi | ire 
 of the river bed at different stages of the water, the kind of matei 
 forming or moving along the bed, the figure and movements of sac »d- 
 waves, the slope of water surface, the discharge, and the transve: f s0 
 curves of velocity. 
 
 The parties engaged in these physical surveys are employes of il'hc 
 Commission, many of whom had previously been engaged in simijlhir 
 studies. They commenced work' in the low river season, and it is hopl| e( i 
 that the funds available will enable them to continue till the spring 
 floods have subsided. 
 
 Borings .—A boring party has been organized to determine the dep 
 of the alluvial deposits and the character of underlying strata in por¬ 
 tions of the river requiring improvement. These borings have be|P 11 
 finished in the vicinity of Memphis and Helena, and others are to B-” 3 
 made at Choctaw Bend and other points. 
 
 th 
 
 SURVEYS AND EXPENSES OF COMMISSION. 
 
 It is necessary that the surveys and examinations which have be^T 0 
 undertaken by the Commission and are now in progress below Caii.vh 
 under the authority conferred in section 3 of the act, should be continued^* 
 and that surveys should be commenced above Cairo, so far as they m? 
 be considered necessary for the advantageous progress of works of id 
 provement. For these purposes and for salaries, mileage, traveling ad 1 
 office expenses of the Commission, there will be required during tl[ je 
 coming fiscal year the sum of $200,000. 
 
 In view of the prospect of an extreme flood on the Lower Mississipf 
 which would afford an unusual opportunity for observations upon tlu e 
 operations of floods, the importance of an early appropriation of tl ie 
 amount estimated for surveys under the Commission is earnestly repre¬ 
 sented, in order that the system of observations already inaugurate 
 may be made continuous through the flood season. 
 
 SYSTEMS OF IMPROVEMENT. 
 
 e 
 
 Pil 
 
 This Commission is not prepared, nor is it deemed necessary at th 
 present time, to submit a full and detailed report, with estimates of fim 
 cost, upon any general system of river improvement. It seems prope L 
 however, that all the several methods and plans embraced by the com¬ 
 prehensive and distinctive language used in the act, so far as they appl.y 
 to or have direct bearing upon any of the objects contemplated thereif 1 ? 
 should be defined, and that the general principles which have been kepyk 
 in view in adopting a plan which will concentrate rather than dispersj 0 
 the waters of the river, as the principal agent in securing the needed 
 improvement in its navigation, should be briefly stated. 
 
 Whatever seems needful to be]said upon the “ outlet system,” which i 
 being one of diffusion and waste and not of concentration, does nc'f 
 commend itself to the judgment ot the Commission, will be embodied ii- 1 
 this report. 
 
 The Mississippi Liver, aside from its great length and other elementSj 
 of wonderful and impressive magnitude, and the energy with which it^ 
 maintains its tortuous and everchanging route to the sea, ranging over' 
 a broad alluvial region of its own creation, does not appear to be char 
 acterized by any phenomena peculiar to itself, or by any physical fea- 
 
 ) 
 
REPORT OF MISSISSIPPI RIVER COMMISSION. 
 
 7 
 
 tures not found in greater or less degree in other turbid streams flowing 
 through alluvial deposits. Its waters within the limits of the alluvial 
 district constantly carry large, although very variable, quantities of sed¬ 
 imentary matter. This sediment, or silt, derived from tributary streams, 
 from caving banks, and from its own bed by erosion and scour, is borne 
 along by the current in such manner that a large part of it is held in 
 more or less constant suspension in the water, while a portion is rolled 
 or swept along upon the bottom. 
 
 An exact relation between the quantity of silt transported or moved 
 along by a stream, and the longitudinal velocity of its current, has not 
 been discovered. Longitudinal velocity, however, is always accom¬ 
 panied by motion in other directions. Without upward motiou of the 
 water, there can be no continued suspension of sedimentary matter 
 in it. 
 
 When, on any given reach of the same stream, the velocity, as usually 
 measured by meters or floats, is increased, the vertical motion, and there¬ 
 fore the silt sustaining and transporting power of the stream, is also 
 increased. It does not follow from this, however, that in different silt¬ 
 bearing streams, or in different reaches of the same stream, or even in 
 the same reach through varying stages of water or different seasons of 
 the year, the same velocity of current invariably sustains and transports 
 the same amount or proportion of sedimentary matter. No fixed rela¬ 
 tion has been discovered between a volume of water and the amount of 
 sediment iu it for any given observed velocity. The supply of earthy 
 matter is very irregular, varying greatly, irrespective of changes of ve¬ 
 locity, with fluctuations in the stage of river, the relative discharge of 
 different tributaries, the seasons of the year, the conditions governing 
 rainfall, alternations of freezing aud thawing, the kind of crops cultivated 
 in the vicinity, aud other causes. 
 
 Any reduction of velocity by lessening the sustaining and transport¬ 
 ing power of the water, and by arresting some of the heavier particles 
 which the diminished current is unable to move along upon the bottom, 
 will tend to cause a deposit of solid earthy matter and raise the bed of 
 the stream. The direct effect of raising the bed is to raise the surface 
 slope. The surface slope may also be increased by reduction of the 
 river’s length by cut offs and other causes. 
 
 Conversely, if the velocity be increased from any cause, a greater 
 amount of silt will be thrown into suspension, which will be supplied by 
 erosion. A lowering of both the bed of the stream and the surface slope 
 will therefore ensue. 
 
 These general principles may be briefly aud comprehensively stated 
 as follows, viz: If the normal volume of water in a silt-bearing stream 
 flowing iu an alluvial bed of its own formation be permanently in¬ 
 creased, there will result an increase of velocity, and consequently of 
 erosion and silt-beariug power, an increase in area of average cross-sec¬ 
 tion, aud an ultimate lowering of the surface slope ; and, conversely, if 
 the normal flow be decreased in volume, there will erjsue a decrease of 
 velocity, silt-transporting power, and mean sectional area, and an ulti¬ 
 mate raising of the surface, slope. 
 
 THE OUTLET SYSTEM. 
 
 It has been supposed bynnany persons that,- because the immediate 
 effect of a crevasse during a flood is the reduction of the height of the 
 river’s surface in the vicinity of the crevasse and below it, lateral outlets, 
 either natural or artificial, by which the flood-waters of the river are 
 
8 
 
 REPORT OF MISSISSIPPI RIVER COMMISSION. 
 
 drawn oft' and conveyed through a shorter route to the sea, tend to pre¬ 
 vent the recurrence of destructive floods, by supplying additional ave- < 
 nues for their escape. This method would undoubtedly be effective if 
 the flood-waters of the Mississippi were not highly charged with sedi¬ 
 mentary matters, which are held in suspension in the water by the cur¬ 
 rent. To support this immense mass of earth and sand in suspension, t 
 and thus insure its transportation to the Gulf, the velocity of the current 
 must be sustained. Without stopping to determine, or even discuss, 
 the character of the relation which exists between the various velocities 
 of current and the proportionate quantities of sediment which such ve¬ 
 locities are capable of carrying in suspension, the fact seems to be estab¬ 
 lished that when the current is checked in its natural flow during floods, 
 a deposit of sediment will occur. Shoals are found in the river immedi¬ 
 ately below crevasses, which it is difficult to refer to any other cause than 
 the loss of current-velocity which takes place below the crevasse. As a 
 portion of the volume of the river is drawn off by the crevasse when it 
 is first made, it is impossible that the current below the crevasse can 
 then be as rapid as it was before its occurrence. Being less rapid, it is 
 unable to sustain the whole quantity of matter held in suspension by 
 the more rapid current above the outlet, and consequently its surplus 
 sediment falls to the bottom below the crevasse. This deposition con¬ 
 tinues until the size of the river below the crevasse has been so reduced 
 by the shoaling that the current is again restored through the short 
 distance in which the bottom of the river has been thus raised and the 
 channel diminished. If the crevasse remained open, however, for sev¬ 
 eral years, it is evident that the shoal will continue to extend down the 
 stream, for the reduced velocity will still exist in the river below the 
 shoal. If the crevasse be kept open indefinitely, the shoaling will con¬ 
 tinue to extend down the stream until certain other injurious effects are 
 produced, which will be presently referred to. 
 
 It is a well established law of hydraulics that the ratio of frictional 
 resistance per unit of volume increases if the sectional area be dimin¬ 
 ished. Thus, if the volume of the river were suddenly divided by an 
 island into two channels, the water flowing in them would encounter 
 more frictional resistance than it met with while flowing in a single 
 channel. Hence the currents through these channels would be more 
 sluggish. As the water is charged with sediment the sluggish current 
 would cause a deposit in the channels which would first begin at their 
 upper ends, and would continue until the bottoms of the two channels 
 would be so steepened that the current would attain a velocity capable 
 of carrying the suspended sediment through them without further 
 deposit. If the two channels were of nearly equal length and size, they 
 would probably remain permanent, and the slope of the river’s surface 
 in flood time would be found to be steeper through them than above and 
 below, where the volume flows in a single channel. If one of the two 
 channels were materially longer than the other, the effort of the river 
 to increase the steepness of the longer channel would be abortive, be¬ 
 cause its slope would be controlled by the shorter one. A shoal in the 
 upper end of the long channel would, however, be built up to such 
 height by the depositing action of the sluggish water in it, as finally to 
 shut it off altogether from any connection with the river, while the still 
 water at the lower end of such chaunel would promote the deposition of 
 sediment at that end to such an extent as to build it up also, and thus ^ 
 completely separate the long channel from the main body of the river; 
 in the mean time the shorter channel would have enlarged so as to ac¬ 
 commodate the entire river. The longer channel would, in this event, 
 
REPORT OF MISSISSIPPI RIVER COMMISSION. 
 
 9 
 
 constitute a lake, like one of tlie many lakes which are seen on a map of 
 the alluvial basin of the river. Being removed from the influence of 
 overflows, these lakes remain deep and clear for many centuries. The 
 phenomenon just described invariably accompanies the formation of a 
 cut-off. When one of these occurs, the volume of the river is at first 
 divided into two channels of unequal length, an island being left be¬ 
 tween them. 
 
 In the case of a crevasse an island is also formed, having the main 
 body of the river on the one side of it, and the crevasse channel on the 
 other side. As the volume flowing in the main channel below a crevasse 
 lias been decreased by the amount drawn off through it, a steeper slope 
 in the main river, if the crevasse be kept permanently open, becomes 
 inevitable; because the shoal below the outlet, as it grows in leugth 
 down stream from the deposition of successive floods, gradually increases 
 the frictional resistance of the volume flowing through that diminished 
 channel, and this tends to check the current of the river above the 
 crevasse, and thus the shoaling of the river bed and the raising of the 
 flood line above the site of the outlet ensue as a secondary and permanent 
 effect. 
 
 It is in this way that silt-bearing streams flowing through alluvial de¬ 
 posits have the ability to increase or steepen their surface slopes, and 
 thus recover the velocity of their currents and adjust them to the work 
 of transporting the sedimentary matter with which the flood-waters are 
 charged so that this matter may be carried without loss or gain. In 
 proof of the correctness of these views, and of their full accordance with 
 well established hydraulic laws, we have the evidence of this relation 
 between slope and volume presented in the phenomena of silt-bearing 
 streams all over the world. Wherever such streams flow through 
 alluvial deposits, other conditions being the same, the slope is least 
 where the volume is greatest; and, conversely, the slope is found to be 
 invariably increased as the volume is diminished. The Mississippi 
 throughout its alluvial basin, not only in its main trunk but in all of its 
 outlets, presents no exception to this peculiar feature. Among numer¬ 
 ous illustrations of this law the following examples may be cited. 
 
 The fall of the Atchafalaya is about six inches per mile from its head 
 to the Gult level, while the fall of the Mississippi from the same point 
 is less than two inches per mile. The volume of the Atchafalaya is only 
 about one-twelfth as great as that of the Mississippi where they sepa¬ 
 rate. The fall of the South Pass is three inches per mile, whilst that of 
 the Southwest Pass is but two inches per mile. The volume of the South 
 Pass is only about one quarter as large as that of the Southwest Pass. 
 
 As water selects the line of least resistance in flowing from a higher 
 to a lower level, it folloAVS that, inasmuch as that portion of the 
 Mississippi floods which enters the A tchafalaya seeks the Gulf level 
 through a route not half so long as that which follows the main river, 
 and as it has a descent threefold greater than the portion that flows 
 in the main liver, the resistance in the shorter and steeper route of 
 the Atchafalaya must be so much greater that these elements which 
 tend to increase the current are so far neutralized as to produce in both 
 routes to the sea that rate of current which is capable of transporting 
 the sediment without loss or gain to the Gulf level, and thus a condition 
 of equilibrium is established between these two routes to the sea. It 
 seems unnecessary to state that the ratio of frictional resistance to vol¬ 
 ume of water resulting from the smaller size of the Atchafalaya is so 
 much greater than that in the main river, that this condition of 
 equilibrium or regimen of the two channels is the result. Anything 
 
10 
 
 REPORT OF MISSISSIPPI RIVER COMMISSION. 
 
 which will tend to increase the flow permanently through either route 
 would, if unchecked, have a tendency to cause the entire river to find 
 its way ultimately through that route to the sea by lessening in it, as it 
 enlarged, the ratio of frictional resistance to volume of water Rowing in 
 if. The subdelta building ability of the smaller passes by which they 
 prolong their length and thus flatten their slopes, will invariably tend 
 to cause their extinction by results similar to those hereinafter referred 
 to at Cubitt’s Gap, the Jump, and the extinct outlets below them. This 
 cause has tended to the extinction of many well known bayous below the 
 Atchafalaya. That the Atchafalaya remained so long unaltered, and is 
 now evidently enlarging, is owing to important changes in the bed of 
 the Mississippi near it, by which a large portion of the floods of Red 
 River have been recently discharged through it. 
 
 This explanation of the relation between slope and volume is, of . 
 course, applicable to the other existing outlets referred to in this con¬ 
 nection. For this reason the Commission believes that no surer method 
 of ultimately raising the flood-surface of the river can be adopted than 
 by making lateral outlets for the escape of its flood-waters. The rais¬ 
 ing of the flood-surface necessitates an increase in the height of the 
 levees and leaves shallower channels for navigation. 
 
 As the system of improvement proposed by the Commission is based 
 upon a conservation of the flood-waters of the river, and their concen¬ 
 tration into one channel of an approximately uniform width, it would 
 seem scarcely necessary further to consider a system based upon theo¬ 
 ries and arguments so diametrically opposed to it as the outlet system 
 is thus shown to be. 
 
 Allusion has only been made so far to phenomena attending long 
 established or permanent outlets. A proposition to provide for im¬ 
 proving the navigation of the Mississippi River and for the reclama¬ 
 tion of the low lauds of the States bordering thereon” having been pre¬ 
 sented to the consideration of Congress in House bill 5113, Forty-fifth 
 Congress, third session, it is the duty of the Commission to report upon 
 the merits of the system as set forth in the bill. The first feature of 
 the plan consists in opening an outlet, about ten miles below New Or¬ 
 leans, from the river into Lake.Borgne. The idea of making an outlet 
 into this lake was suggested by Mr. Charles Ellet, jr., civil engineer, in 
 1852 (see Ex. Doc. 20, Thirty-second Congress, first session), in an 
 elaborate report to the Secretary of War on the inundation of the Mis¬ 
 sissippi River. 
 
 The proposition was subsequently discussed at considerable length 
 in the report of Humphreys and Abbot, and rejected by them as im¬ 
 practicable. It was again taken up and examined into by the Levee 
 Commission in 1875, and was by it likewise rejected. 
 
 In considering the proposed outlet at L ike 13 )rgne, it is necessary to 
 refer to phenomena attending a class of outlets which cannot be con¬ 
 sidered as permanent ones, and which are similar in their characteristics 
 to those which would attend the proposed one at Lake Borgne, for the 
 reason that the river immediately after their occurrence, whether from 
 artifical or natural causes, commences a process of subdelta formation 
 which in the course of a few years effects their complete closure. 
 
 On examination of the appended United States Coast-Survey map, 
 showing that part of the delta embracing the passes and about forty 
 miles from the main river, several remarkable systems of extiuct chan¬ 
 nels will be found on each side of the three great passes. The vermicu- 
 lated appearance of these old outlets is particularly noticable on the 
 west side of the Southeast Pass and on the west side of the Southwest 
 
REPORT OF MISSISSIPPI RIVER COMMISSION. 
 
 11 
 
 Pass. The process by which the river closed them up and shut them 
 * off is clearly illustrated by a similar process uow occurring about three 
 miles above the Head of the Passes. At this point on the map referred 
 to will be seen the largest and most recent outlet or mouth of the Mis¬ 
 sissippi. It occurred during a flood seventeen years ago, and is known 
 ^ as Cubitffs Gap. It was caused by a small canal between the river and 
 the Gulf, used by fishermen in visiting the oyster banks in the vicinity. 
 
 The river and the Gulf at this point were then separated by a narrow 
 margin less than one thousand feet wide. The difference in the surface 
 height of the river and the mean level of the Gulf at the time was a 
 little over three feet. The surface slope or fall through the gap was 
 therefore at first at the rate of about fifteen feet per mile. The rapidity 
 of the escaping water with this enormous fall made the crevasse over 
 two thousand feet wide in a few years, with depths of one hundred feet 
 and over in the gap where the river bank had formerly stood. 
 
 As soon as the water passed through the gap its velocity was gradu¬ 
 ally lost, and the immense volume of sediment with which it was charged 
 was thrown down within a fan-shaped area embracing probably twenty 
 or thirty square miles. The earlier maps of the Coast Survey show no 
 islands outside the gap, but the more recent ones show, by the incipient 
 islands and shoals which now surround it, how rapid has been its sub¬ 
 delta formation. These islands are subdividing the single volume of 
 the river water issuing from it into innumerable bayous and little chan¬ 
 nels, none of them having at this time a greater depth than 7 feet. 
 Each flood serves to build up these islands higher and extend their area 
 further into the Gulf. And as this island-building process continues 
 out gulfward, these small channels become more distinctly outlined from 
 j the depositing action which goes on most rapidly in the more sluggish 
 water along their shore lines. Every overflow serves to build up the 
 banks of these channels and to extend them out into the gulf, but in 
 their prolongation is to be found the cause which finally cuts off and 
 ' separates them, perhaps forever, from the main river. The difference 
 of level between the river and the Gulf remains the same that it was at 
 the time of the crevasse, but the enormous slope, through the gap, at 
 first equal to about 15 feet per mile, and which must have created an 
 exceedingly rapid current during the first few days after the gap was 
 made, now no longer exists. Every addition to the length of the sep¬ 
 arate channels which are now forming through the subdelta flattens 
 their slope and consequently reduces the current through them. Ulti¬ 
 mately these currents will become too sluggish to transport the sediment 
 contained in the water, and it will be dropped at the upper or river ends 
 of these channels, and they will be finally shut off entirely from all con¬ 
 nection with the main river, just as those were which are seen on the map 
 on the west side of Southwest and Southeast passes. 
 
 Each successive overflow of the river bank will tend to increase the 
 distance between the river and these extinct outlets, and the wound 
 made in the side of the river by Oubitt’s Crevasse wiil then have been 
 completely healed by a natural process. 
 
 Twenty-one miles above the Head of the Passes, a gap similar to Cu- 
 bitt’s occurred about forty years ago, called “ The Jump.” Au immense 
 subdelta was formed there in consequence, and upon it there are now 
 several rice plantations and extensive forests, many of the trees being 
 r; over 12 inches in diameter. 
 
 Innumerable bayous permeate this subdelta and lead to the sea, 
 each having at its mouth a miniature bar like those at the mouths of 
 
12 
 
 REPORT OF MISSISSIPPI RIVER COMMISSION. 
 
 the great passes, none of them having more than 2 feet of depth at low- 
 water. 
 
 At the river entrance to the The Jump, the depth is but -3 or 4 feet, 
 and in a few years more it will be fully closed by the river deposits. 
 
 The same effort which the river is successfully making to close np 
 The Jump and Cubitt’s Crevasse (both of which are high and low water 
 outlets), it is making at the celebrated Bonnet Carre Crevasse, which, 
 being through an artificial embankment or levee, only discharges at 
 high-water. The immense deposits which it has carried out and spread 
 over the land near it have served greatly to reduce the volume of water 
 discharged by the crevasse. 
 
 Should an outlet be made to connect the river with Lake Borgne, re¬ 
 sults precisely similar to those which have occurred at Cubitt’s Gap and 
 The Jump must be confidently anticipated. Below Cubitt’s Gap it is an 
 undisputed fact that the former depth of the river has been largely re¬ 
 duced since the gap occurred. Below The Jump it is not so definitely 
 known what the shoaling has been, as charts of previous soundings are 
 not now available if any exist, but the Light-House Board has placed 
 two buoys a short distance below The Jump, to warn vessels away from 
 the shoals which exist there. It is not possible to make the proposed 
 outlet into Lake Borgne without creating a shoal in the river below it, 
 and it is not possible to keep it permanently open except at great cost 
 in dredging away the subdelta that would be formed by it. Nor could 
 it be kept permanently open without the slope of the river being ulti¬ 
 mately increased from the Head of the Passes to the outlet; after which 
 it would raise the Hood surface of the river above the outlet. 
 
 With reference to that part of the plan set forth in House bill 5413, 
 relating ro the Atchafalaya outlet, the Commission suggest that, as 
 Major Benyaurd, of the United States Corps of Engineers, in charge of 
 the government works upon this portion of the Mississippi, has now 
 under consideration the question of the permanent improvement of the 
 mouth of the Bed Biver, with the intention, as expressed in his last 
 annual report, of making a special report thereon at the earliest possible 
 moment, it is not deemed advisible that any work at this locality, except 
 what may be required to check the enlargement of the Atchafalaya, 
 should be recommended by this Commission in anticipation of the ma¬ 
 tured views and opinions of that officer. This can be done in such 
 locality and in such manner as will not interfere with the navigation of 
 the Bed and Atchafalaya Bivers, and at a cost not exceeding $10,000. 
 
 That part of the plan which involves turning the Bed Biver into the 
 Calcasieu, from a point above Alexandria, is entirely impracticable, it 
 having beeu ascertained by a line of levels run across from Alexandria, 
 under Major Benyaurd’s direction, that the bed of the Calcasieu Biver 
 is G3 feet higher than the water surface of Bed Biver in time of ordi¬ 
 nary flood, while its ordinary flood level is 73 feet above that of Bed 
 Biver. The distance between the two rivers, on the line of levels, which 
 is the shortest line that can be run from Alexandria, is 23.8G miles. 
 
 If it is proposed to avoid this difficulty by making the connection with 
 the Calcasieu at a point sufficiently near its mouth to secure the requisite 
 descent in the cut, not only would the expense be so enormous as to be 
 practically prohibitory, but there would still remain the danger, unless 
 the dimensions of both the cut and the lower Calcasieu be made im¬ 
 moderately large, of widespread destruction by floods during every high- 
 liver stage through the region traversed by the outlet. 
 
 Although other equally novel propositions are setforth for considera¬ 
 tion by Congress in House bill No. 5113, as part of this extensive outlet 
 
REPORT OF MISSISSIPPI RIVER COMMISSION. 
 
 13 
 
 system, which in the language of the bill is designed to effect the u deep¬ 
 ening of the channel of the Mississippi River, reducing the mud flow 
 ■\ therein, and filling up the swamps and low places by the deposit, and 
 diminishing the volume of water by absorption and evaporation,” the 
 Commission deems it unnecessary to report upon them in detail after this 
 exposition of the Lake Borgne and Calcasieu outlets, inasmuch as the 
 latter constitute the chief features of the entire scheme, and the former 
 are, like them, quite impracticable. 
 
 Before dismissing this subject, however, it is pertinent to say that the 
 statements which have been published to support this scheme, regarding 
 the effect produced by the Bonnet Carre outlet, in lowering the flood-line 
 above and below it, have been greatly exaggerated. 
 
 The Board of Engineers for the improvement of the low-water navi¬ 
 gation of the Mississippi River below Cairo, to whom House bill No. 
 5413 was referred, say in their report of January 28, 1879, with reference 
 to the effect of the proposed outlet: 
 
 The probable immediate effect of this outlet upon the Hood-level of the Mississippi 
 will next be considered. The best basis for a safe estimate is the measured effect of 
 the Great Bell crevasse which occurred just above New Orleans on the right bank, in 
 1858. Its maximum discharge occurred August 1-17, and was 80,000 cubic feet per 
 second, or about 1-12 of the total discharge of the river at that date. 
 
 This lowered the water surface 1.5 feet at its site and produced no sensible effect at 
 Baton Rouge, 124 miles above. One fundamental error of the engineering project on 
 which this bill is based lies in overestimating the distance to which the inlluence of 
 an outlet extends above its site, and it will be well to elaborate this point. 
 
 The influence of the Gulf upon the river at high stages is hardly felt above the mouth 
 of Reel River. The high-water and the low-water slopes of the water surface above 
 this point are sensibly the same for long distances. Nothing can be done toward mod¬ 
 ifying the water-level below which will exert any marked effect at any considerable 
 distance above. That this is so was proved by the Red River and Raccourci Cut-offs, 
 * which shortened the Mississippi 39 miles near the mouth of Red River and lowered the 
 high-water mark there 4.6 feet in the flood of 1851. This beneficial effect diminished 
 rapidly at points higher up the river, and was not felt at all at a distance of 100 
 miles. 
 
 The same principle of hydraulics which is fundamental, and which logically results 
 ✓ from the small function of the slope entering all discharge formulae, is also illustrated 
 by accurate tidal measurements upon the Mississippi. Thus, for spring tides the oscil¬ 
 lations are— 
 
 At the Gulf in flood stages of river, 1.7 feet; in low stages of river, 1.7 feet. 
 
 At the Forts (36 miles) in flood stages of the river, 0.6 foot; in low stages of river, 
 1.4 feet. 
 
 At Carrollton (120 miles) in flood stages of the river, 0.3 foot; in low stages of river, 
 
 1.1 feet. 
 
 At Donaldsouville (192 miles) in flood stages of the river, 0.0 ; but in low stages of 
 river, 0.9 foot. 
 
 At Baton Rouge (244 miles) in flood stages of the river, 0.0 foot; in low stages of 
 river, 0.4 foot. 
 
 At Red River (315 miles) in flood stages of the river, 0.0 foot; in low stages of river, 
 0.0 foot. 
 
 It is true that the temporary duration of the tidal rise at the river mouth diminishes 
 its effect on the upper river, but nevertheless the facts given for the tides illustrate 
 the general fact that the effect of lowering the river surface at a given point dies out 
 rapidly in ascending. 
 
 THE LEVEE SYSTEM. 
 
 Levees have never been erected upon the banks of the Mississippi 
 River except for the special purpose of protecting the alluvial lands 
 from overflow. They have, therefore, always had sole reference to the 
 high-water stage, and the degree to which levees might prudently be 
 r / relied upon “ to improve and give safety to navigation,” “ promote and 
 facilitate commerce, trade, and the postal service,” has not hitherto eu- 
 
 ) 
 
14 
 
 REPORT OF MISSISSIPPI RIVER COMMISSION. 
 
 tered into the question of the construction and maintenance of a levee 
 system. 
 
 There is no doubt that the levees exert a direct action in deepening 
 the channel and enlarging the bed of the river during those periods of 
 “ rise ” or “ flood ” when by preventing the dispersion of the flood-waters 
 over the adjacent low-lands, either over the river banks or through bay¬ 
 ous and other openings, they actually cause the water to rise to a higher 
 level within the river-bed than it would attain if not thus restrained. 
 
 It would seem to follow, from the law that the volume of water flow¬ 
 ing in the bed determines the size, that prior to the construction of 
 levees the area of the mean cross section of bed of the Mississippi River 
 must have been less than it was after the levees had reached their most 
 efficient condition, assuming, what is believed to be true, that the aver¬ 
 age rainfall iu the Mississippi Valley has not materially changed with¬ 
 in the last hundred .years. 
 
 There is some evidence in a comparison of the results of Young, Pous¬ 
 sin and Tuttle’s examination of 1821, with later surveys, that the width 
 of the river has increased since that date. 
 
 As silt-bearing streams in alluvial districts have a tendency to as¬ 
 sume in the straight reaches cross-sections which are arcs of circles, and 
 in the bends curves of deeper forms, it follows that any general widen¬ 
 ing of the river resulting from concentration or increase of volume, 
 which may have taken place, would as a rule be accompanied by a gen¬ 
 eral and corresponding deepening as the result of such general enlarge¬ 
 ment, atthough local shoalings, temporarily injurious to navigation, 
 might occur. 
 
 There is reason to believe that during the period when levees were in 
 their most perfect condition, from 1850 to 1858, the channel of the river 
 was better generally for purposes of navigation than it has been since 
 that time. 
 
 It is known that during the last twenty y ears the levee system has 
 been continuously interrupted by a great number of crevasses between 
 Cairo and Red River. 
 
 Before the levees were built, a large portion of the flood-waters spread 
 out over the banks of the river in a thin sheet, of which the average 
 depth at the margin of the stream, where it escaped, did not probably 
 exceed a few inches, or, at most, a foot. The immediate effect of the 
 levees would be to increase the volume and height and accelerate the 
 velocity of the flood-waters between them, resulting in an erosion and 
 deepening of the river-bed, and ultimately in a corresponding lowering 
 of the flood slope in accordance with the geueral law already quoted, 
 that an increase in the normal volume of discharge iu a sedimentary 
 stream, flowing through alluvial deposits, results ultimately in a lower¬ 
 ing of the flood surface. It would seem, therefore, that a closure of the 
 crevasses might be expected to accelerate the removal of those shoals 
 which have been produced by- them, and if theirclosure be accompanied 
 by the requisite contraction of the chauuel to a more nearly uuiform 
 high-water width, a lowering of the flood level may be expected to such 
 extent as will ultimately render the maintenance of the levees as an aid 
 to navigation practically needless above Red River, and greatly lessen 
 the necessity of their permanent maintenance for that purpose below 
 Red River, even at a reduced height. 
 
 While it is not claimed that levees in themselves are necessary as a 
 means of securing ultimately a deep channel for navigation, it is believed 
 that the repair and maintenance of the extensive lines already existing 
 will hasten the work of channel improvement through the increased 
 
REPORT OF MISSISSIPPI RIVER COMMISSION 
 
 15 
 
 scour and depth of river-bed which they would produce during the high- 
 river stages. They are regarded as a desirable, though not a necessary, 
 adjunct in the general system of improvement submitted. 
 
 It is obvious that levees are, upon a large portion of the river, essen¬ 
 tial to prevent destruction to life and property by overflow. They give 
 safety and ease to navigation and promote and facilitate commerce and 
 trade by establishing banks or landing places above the reach of floods, 
 upon which produce can be placed while awaiting shipment, and where 
 steamboats and other river craft can laud in times of high water. 
 
 In a restricted sense as auxiliary to a plan of channel improvement 
 only, the construction and maintenance of a levee system is not de¬ 
 manded. But in a larger sense, as embracing not only beneficial effects 
 upon the channel, but as a protection against destructive floods, a levee 
 system is essential; and such system also promotes and facilitates com¬ 
 merce, trade, and the postal service. 
 
 A levee system aids and facilitates the postal service by protecting 
 from injury and destruction by freshets and floods the various common 
 roads and railways upon which that service is conducted to and from 
 the river bank, and generally within that portion of the alluvial region 
 subject to overflow. Moreover, the permanent maintenance below Cairo 
 of a connected levee system, a system of sufficient strength to inspire 
 confidence in its efficiency, or the demonstration, by the achieved results 
 of an improved river, that overflow need no longer be seriously appre¬ 
 hended, would act as a prompt and powerful stimulant in rapidly de¬ 
 veloping a largely increased trade and commerce in all the products of 
 agricultural industry indigenous to that region, and in those branches 
 of manufacturing enterprise related thereto. 
 
 The foreging is submitted as the opinions of this Commission, with re¬ 
 gard to the attributes and functions of levees, and their general utility 
 and value. The views of the several members, however, are not in en¬ 
 tire accord with respect to the degree of importance which should attach 
 to the concentration of flood-waters by levees, as a factor in the plan of 
 improvement of low-water navigation, which has received the unanimous 
 preference of the Commission. 
 
 The breaks in the levees were estimated in January, 1875, by the com¬ 
 mission for the reclamation of the alluvial basin of the Mississippi River, 
 to amount to 8,065,700 cubic yards. It is believed that the repairs done 
 in Louisiana and Mississippi siuce that time will fully equal the enlarg- 
 rnent of the openings in Arkansas and Missouri. The estimate of the 
 cost of closing the breaks in the existing system of levees to the former 
 height is based upon this hypothesis. 
 
 The want of completed surveys and the limited supi)ly^ of labor would 
 render diffirult the construction of more than one-half of this amount 
 of work in any one year. 
 
 Estimate of cost. 
 
 For closing to their former height the gaps in the existing levees between 
 Cairo and New Orleans, 8,065,700 cubic yards of earthwork, at 23 cents 
 
 per yard. $1,855,111 
 
 Add for contingencies. 164,889 
 
 Total for repairs of existing levees. $2, 020, 000 
 
 This does not include the cost of maintenance, for which no reliable 
 estimate can be made in the absence of data giving the required dimen¬ 
 sions' of the levees and their positions relative to caving banks. For 
 the absolute prevention of destructive floods, the former height of the 
 
16 
 
 REPORT OF MISSISSIPPI RIVER COMMISSION. 
 
 levees would have to be increased, but no exact estimate of the cost of 
 these higher levees can be made at present for want of the necessary 
 data. 
 
 PLAN OF. IMPROVEMENT RECOMMENDED. 
 
 The bad navigation of the river is produced by the caviug and ero¬ 
 sion of its banks, and the excessive widths and the bars and shoals 
 resulting directly therefrom. 
 
 It has been observed in the Mississippi River, and is indeed true of 
 all siltbearing streams flowing through alluvial deposits, that the 
 more nearly the high river width, or width between the banks, ap¬ 
 proaches to uniformity, the more nearly uniform will be the channel 
 depth, the less will be the variations of velocity, and the less the rate 
 of caving to be expected in concave bends. This would seem to be so 
 in the very nature of things, because uniformity of width secured by 
 eontraction will produce increased velocity, and therefore increased 
 erosion of bed at the shoal places, accompanied by a corresponding de¬ 
 posit of silt at the deep places, and consequently greater uniformity of 
 depth. 
 
 Uniform depth joined to uniform width, that is to say, uniformity of 
 effective cross section, implies uniform velocity, aud this means that 
 there will be no violent eddies and cross currents, and no great aud sud¬ 
 den fluctuations in the silt-transporting power of the current. There will 
 therefore be less erosion from oblique currents and eddies, aud no form¬ 
 ations of shoals and bars produced by silt taken up from one part of the 
 chaunel aud dropped in another. As the friction of the bed retards the 
 flow of the water, any diminution of the friction will promote the discharge 
 of floods. The frictional surface is greater in proportion to volume of 
 discharge where the river is wide and shoal than where it is narrow aud 
 deep. It follows, therefore, that after the wide shoal places are suitably 
 narrowed, aud the normal sectional area is restored by deepening the 
 channel, the friction will be less than it was before. This will result in 
 a more easy and rapid discharge of the flowing water, aud consequently 
 in a lowering of the flood-surface. It would seem, therefore, that the 
 plan of improvement must comprise, as its essential features, the con¬ 
 traction of the water-way of the river to a comparatively uniform width, 
 and the protection of caving banks, and this is presumed to be the plan 
 referred to in the act as the “jetty system.” It is known, from observa¬ 
 tion of the river below Cairo, not only that shoals and bars, producing 
 insufficient depth and bad navigation, are always accompanied by a 
 low-water width exceeding 3,01)0 feet, but that wherever the river does 
 not exceed that width there is a good channel In other words, bad 
 navigation invariably accompanies a wide low-river water-way, and 
 good navigation a narrow one. 
 
 The work to be done, therefore, is to scour out aud maintain a chau¬ 
 nel through the shoals and bars existing in those portions of the river , 
 where the width is excessive, and to build up new banks and develop 
 new shore lines, so as to establish as far as practicable the requisite 
 conditions of uniform velocity for all stages of the river. 
 
 It is believed that this improvement can be accomplished below Cairo 
 by contracting the low-water channel-way to an approximately uniform 
 width of about 3,000 feet, for the purpose of scouring out a channel 
 through the shoals and bars, and by causing, through the action of ap¬ 
 propriate works constructed at suitable localities, the deposition of sand 
 aud other earthy materials transported by the water upon the dry bars 
 
REPORT OF MISSISSIPPI RIVER COMMISSION. 
 
 17 
 
 and other portions of the present bed not embraced within the limits of 
 
 r the proposed low-water channel. The ultimate effect sought to be pro- 
 
 * duced by such deposits is a comparative uniformity in the width of the 
 high-water channel of the river. 
 
 It is believed that the works estimated for in this report will create 
 Jf j x and establish a depth of at least 10 feet at extreme low stages of the 
 \ river over all the bars below Cairo, where they are located. 
 
 It is the opinion of this Commission that, as a general rule, the chan¬ 
 nel should be fixed and maintained in its present location; and that no 
 attempt should be made to straighten the river or to shorten it by cut¬ 
 offs. 
 
 The borings which were made in 1879 at New Madrid and Plum 
 Point, by direction of the Board of Engineers for the improvement of the 
 low-water navigation of the Mississippi River below Cairo, and those of 
 more recent date at Memphis and Helena, made under the orders of 
 this Commission, as well as those near Lake Borgue, reported by the 
 levee commission of 1875, and others made along the proposed line of 
 the Fort Saint Philip Canal, and the artesian well sunk at New Orleans, 
 all furnish concurrent evidence of the yielding character of the strata 
 forming the river-bed. This evidence, taken in connection with the fact 
 that deep water is found in all the bends of the river where the width 
 is not excessive, and that these bends have, by their shiftings at one 
 time or another, probably occupied and covered nearly every part of the 
 belt from 10 to 20 miles in width from Cairo to the Gulf, point to 
 the conclusion, if it does not indeed justify it, that there is no extensive 
 stratum of material capable of resisting erosion and preventing the 
 / river from deepening its own bed. In exceptional localities, where the 
 
 .a material is too tough, or the gravel too heavy for removal by scour, 
 
 * dredging may have to be resorted to as an auxiliary, the depth secured 
 by this means being maintained by the works erected for narrowing the 
 stream. 
 
 > Experience, as well in this country as in Europe, justifies the belief 
 that the requisite correction and equalization of the transverse profile 
 of the stream, by developing new shore-lines andbuilding up new banks, 
 may be made chiefly through the instrumentalities of light, flexible, and 
 comparatively inexpensive constructions of poles and brush, and mater¬ 
 ials of like character. These constructions will commonly be open or 
 permeable to such degree that, without too-violently arresting the flow 
 of water, thereby unduly increasing the head and causing dangerous 
 underscour, they will sufficiently check the current to induce a deposit 
 of silt in selected localities. 
 
 The works which have been used in similar improvements are of vari¬ 
 ous forms and devices, such as the hurdle, composed of a line of stakes 
 or light piles, with brush interlaced; the open dike, formed of stakes 
 with waling strips on both sides filled in loosely with brush ; the con¬ 
 tinuous brush mattress, built or woven on fixed or floating ways and 
 f ' launched as fast as completed, as a revetment to a caving bank, the 
 
 mattress used as a vertical or inclined curtain, placed in the stream to 
 check the current, the same laid flat on the bottom as the foundation 
 for such a curtain or as an anchorage for other brush devices ; curtains 
 of wire or brush netting, placed vertically or inclined in the stream ; 
 and various other forms of permeable brush dikes, jetties, or revetments. 
 Some of these methods of construction have been used on the Missis- 
 
 * sippi and Missouri rivers with increasing satisfaction and success, 
 although they cannot yet be regarded as entirely beyond the experi¬ 
 mental stage." In some, perhaps in many localities, works of a much more 
 
 5 solid character than those above indicated may be necessary. 
 
 H. Ex. 58-2 
 
18 
 
 REPORT OF MISSISSIPPI RIVER COMMISSION. 
 
 The closure of deep channels or low-water chutes, with a view of con¬ 
 fining the flow to a single passage, may require substantial dams of 
 brush and riprap stone or gravel, but it is believed the lighter and less 
 costly works will generally suffice. 
 
 By a permeable dike located upon the new shore-line to be developed, 
 connected with the old bank at suitable intervals by cross lines of like 
 character, or by jetties of hurdles or other permeable works projecting 
 from the bank with their channel ends terminating on the margin of 
 the proposed water way, or by any other equivalent works, the area to 
 be reclaimed and raised will be converted into a series of silting basins, 
 from which the water, flowing through the barriers with diminished 
 velocity, will, after depositing its heavier material, pass off and give 
 place to a new supply. In this manner the accretion will go on contin¬ 
 uously through the high-water season, or through two or more seasons 
 if necessary, the works being renewed on the higher level as occasion 
 requires. 
 
 Wherever necessary, the new bank must be protected by a mattress, 
 revetment, or some equivalent device. 
 
 That these methods of improvement are practicable, is shown by the 
 works already executed on the Mississippi and Missouri rivers. 
 
 The plan submitted by the Board of Engineers for the improvement 
 of the low-water navigation of the river below Cairo, in their report dated 
 January 25, 1879 (see House Ex. Doc. No. 41, Forty-fifth Congress, 
 third session,) in which it is recommended that $009,000 be asked for 
 the improvement of the Plum Point Beach, and u that the improve¬ 
 ment be effected by narrowing the shoal and wide portions of the low- 
 water river to about 3,500 feet, and by protecting caving banks where 
 necessary, 77 is substantially adopted for the initial works submitted for 
 construction in this report. 
 
 An accurate estimate of the cost of properly improving the entire river 
 below Cairo cannot be made until after the completion of the surveys 
 now in progress. Moreover, estimates based upon the latest data from 
 those surveys will doubtless require modification in some particulars, to 
 meet subsequent changes in the river, and will perhaps be considerably 
 reduced in the aggregate amount by improved methods of construction 
 developed during the progress of the w r ork. 
 
 INITIAL WORKS. 
 
 Under the authority conferred in section 5 of the act, estimates of 
 cost of certain initial works, constituting a component part of the gen¬ 
 eral system of w r orks contemplated, are submitted. 
 
 Those works of channel contraction and bank protection, which in the 
 judgment of this Commission may be advantageously undertaken dur¬ 
 ing the coming fiscal year or as soon as Congress supplies the 
 means, are confined to an aggregate length of nearly 200 miles of the 
 shoalest water below Cairo, embracing the following localities, viz : 
 New T Madrid, Plum Point, Memphis, Helena, Choctaw Bend, and Lake 
 Providence. 
 
 The estimates are intended to cover the cost of works for contracting 
 the channel and for securing and protecting the banks; for the neces¬ 
 sary outfit of boats, tugs, tools, &c., to carry on the work for local sur¬ 
 veys, the salaries of engineers, superintendents, and inspectors, and the 
 necessary office expenses. Further appropriations will be needed to 
 complete the works, secure their permanence, and develop the full bene¬ 
 fit of the system. 
 
REPORT OF MISSISSIPPI RIVER COMMISSION. 
 
 19 
 
 As regards the final cost, the novelty of the devices to be employed 
 and the absence of experience with respect to the rapidity and degree 
 of their results, forbid any exact estimate $ but it is believed that such 
 additional works as will ultimately be required to complete and render 
 permanent the improvement contemplated in this system at the locali¬ 
 ties specified will not exceed the amount hereinbelow stated as needed 
 for initial works. 
 
 It is considered necessary that a contingent sum, which is inserted in 
 the estimates lor initial work, be appropriated for use in any emergency 
 that may arise for securing or protecting the works at any point after 
 
 the specific appropriation may have been exhausted. 
 
 Estimates. 
 
 New Madrid Reach, 40 miles long: 
 
 Works for contracting the channel and protecting the banks. $776, 000 
 
 For outfit, superitendence, inspection, office expenses, and local surveys.... 147, 000 
 
 Total for New Madrid Reach.'.. $92, 3000 
 
 Plum Point Reach, 38 miles long : 
 
 Works for contracting the channel and protecting the hanks. 599, 000 
 
 For outfit, superintendence, inspection, office expenses, and local surveys... 137, 000 
 
 Total for Plum Point Reach.'. $736, 000 
 
 Memphis Reach, 16 miles long: 
 
 Works for contracting the channel and protecting the hanks. 282, 000 
 
 For outfit, superintendence, inspection, office expenses, and local surveys .. 100, 000 
 
 Total for Memphis Reach. $382,000 
 
 Helena Reach, 30 miles long: 
 
 Works for contracting the channel and protecting the hanks. $515, 000 
 
 For outfit, superintendence, inspection, office expenses, and local surveys... 112, 000 
 
 Total for Helena Reach .... $627, 000 
 
 Choctaw Bend, 35 miles long : 
 
 Works for contracting the channel and protecting the hanks. 464, 000 
 
 For outfit, superintendence, inspection, office expenses, and surveys. 112,000 
 
 Total for Choctaw Bend. $576,000 
 
 Lake Providence Reach, 25 miles long : 
 
 Works for contracting the channel and protecting the hanks. 507, 000 
 
 For outfit, superintendence, inspection, office expenses, and local surveys... 112, 000 
 
 Total for Providence Reach. $619,000 
 
 Contingencies... $250,000 
 
 Should it be determined not to appropriate the amounts estimated for 
 all the initial works, it is considered important that the reduction should 
 be made rather in the number of places at which work is proposed than 
 by reducing the estimates for any one place. 
 
 Estimates for ivories of improvement for the first fiscal year. 
 
 Initial works for channel contraction and hank protection .. $4,113, 000 
 
 Closing gaps in levees. 1,010,000 
 
 Checking enlargement of Atcliafalaya. 10, 000 
 
 e 
 
 Estimates for surveys and for expenses of Commission for fiscal year ending June 30,1881. 
 
 For surveys and examinations above and below Cairo, and the necessary 
 
 salaries and other expenses of the Mississippi River commission. $200, 000 
 
20 
 
 REPORT OF MISSISSIPPI RIVER COMMISSION. 
 
 If Congress shall authorize any extensive works of improvement on 
 the Mississippi, we would respectfully suggest that provision be made 
 by law for the appropriation of such land and materials as may be needed 
 in the work when the same cannot be obtained upon equitable terms by 
 purchase from the owner. We do not contemplate that a resort to such 
 proceedings would often be necessary; but in the absence of any such 
 provision of law, individual owners of the property required might 
 greatly and unjustly enhance the cost of the work. 
 
 Authority to file in the proper court'of the United States an article 
 of appropriation describing the property to be taken, and to have an 
 assessment by competent appraisers of its value, would tend to prevent 
 extortion, and at the same time secure to the individual a just recom¬ 
 pense for the property taken. 
 
 We venture to suggest further that in case the Commission should 
 be continued in existence and the works recommended by it be in whole 
 or in part authorized by Congress, the execution of the work and the 
 expenditure of the appropriations therefor shall not be made part of the 
 duty of the Commission. We think the duties of the Commission should 
 be limited to the preparation of plans, their modification when neces¬ 
 sary, the advisory supervision of the work, and the completion of the 
 surveys and observations. This would secure unity of plan, greater 
 efficiency in the work, and a better system of checks upon the expen¬ 
 ditures than we could hope to secure if the entire work of devising, 
 executing, and disbursing were cast upon the Commission. 
 
 All of which is respectfully submitted. 
 
 Q. A. GILLMORE, 
 
 Lieutenant-Colonel of Engineers , Bvt. Maj. Gen ., 
 
 President Mississippi River Commission. 
 
 CHAS. R. SUTER, 
 
 Major of Engineers , U. S. A. 
 
 HENRY MITCHELL, 
 
 Coast and Geodetic Survey. 
 
 JAS. B. EADS. 
 
 B. M. HARROD. 
 
 Hon. Alexander Ramsey, 
 
 Secretary of War , Washington , D. C. 
 
 APPENDIX 1. 
 
 Washington, D. C. February 16, 1880. 
 Financial statement. 
 
 Amount appropriated for expenses of tlie Mississippi River 
 
 Commission, by act approved June 28, 1879. $175, 000 00 
 
 Amount expended to February 16, 1880, including outstanding lia¬ 
 bilities : 
 
 For surveys and observations. f65,691 21 
 
 For salaries of Commissioners. 5,024 99 
 
 For mileage and inspection. '8,167 88 
 
 For reduction of maps. 1,920 70 
 
 For office expenses. 4,195 22 
 
 Balance which it is estimated will be required during remain¬ 
 der of the fiscal year ending June 30, 1880. 90, 000 00 
 
 - 175,000 00 
 
 SMITH S. LEACH, 
 
 First Lieutenant of Engineers , U. S. A., 
 Secretary Missouri River Commission. 
 
REPORT OF MISSISSIPPI RIYER COMMISSION. 
 
 21 
 
 The Mississippi River Commission, 
 j President’s Office, Army Building, 
 
 * 33 West Houston Street, 
 
 New Yorlc, March 8 , 1880. 
 
 Sir : I have the honor to transmit herewith the minority report of 
 T General Comstock and Mr. Harrison, to be attached to the report of 
 the Mississippi River Commission forwarded with rn.y letter of the 6th 
 instant. 
 
 Very respectfully, your obedient servant, 
 
 Q. A. GILLMORE, 
 
 Lieutenant-Colonel of Engineers, IPvH Maj. Gen ., JJ. S A., 
 
 President Mississippi River Commission . 
 Hon. Alexander Ramsey, 
 
 Secretary of War , Washington , T>. C. 
 
 [Indorsement.] 
 
 Office Chief of Engineers, U. S. Army, 
 
 March 9, 1880. 
 
 Respectfully forwarded to the honorable the Secretary of War, to ac¬ 
 company report of Mississippi River Commission transmitted on the 8th 
 instant. 
 
 H. G. WRIGHT, 
 
 Chief of Engineers , Brig. & Bt. Maj. Gen. 
 
 MINORITY REPORT. 
 
 While of the opinion that an ample depth of water for navigation on 
 ^ the Mississippi River below Cairo can be obtained by contraction of the 
 low-water width at shoal places to about 3,000 feet, erosion being aided 
 by dredging if necessary; and while of the opinion that levees are es¬ 
 sential to prevent injury to alluvial lands by destructive floods, and that 
 outlets should not in general be used, there are some less important 
 points on which we do not concur in the views of the majority of the 
 Commission. 
 
 1. W T e caunot concur in the unqualified form of expression of certain 
 theoretical views, believing them to have too many exceptions to furnish 
 safe bases for practical conclusions. One such statement is : 
 
 If the normal volume of water in a silt-bearing stream, flowing in an alluvial bed of 
 its own formation, be permanently increased, there will result * * * ultimately 
 
 a lowering of the surface slope. 
 
 While this statement and its converse are usually true, they yet omit 
 some factors which influence the relation between discharge and slope. 
 One is the coarseness and quantity of the sediment which the increase 
 of volume brings; another is the ratio of flood to low-water discharge; 
 and another the varying coarseness of the material forming the bed of 
 the river at the same place at different times or at different places. 
 
 When the increase of volume brings with it much coarse sediment, 
 the slope may be increased instead of diminished, by increase of volume. 
 
 ^ This effect has been frequently observed below the mouths of tribu¬ 
 taries. 
 
 Again, if the ratio of flood to low-water discharge could be made to 
 
 f 
 
22 
 
 REPORT OF MISSISSIPPI RIVER COMMISSION. 
 
 approach unity, the annual discharge remaining unchanged, it is prob¬ 
 able that the middle Mississippi would have a smaller slope than at 
 present, approaching that of the river below New Orleans, where the 
 flood rise is small. In that case the annual discharge might be dimin¬ 
 ished without increasing the slope beyond its present value. 
 
 2. We do not concur with the majority of the Commission in their 
 estimate of the value of the closure of gaps in existing levees as a 
 factor in the improvement of low-water navigation ; this estimate being 
 derived in part from the theoretical views already referred to. 
 
 Existing evidence seems to show that during low-water stages the 
 bars below Cairo are usually cut out by the river, and that when the 
 period of low river in the following season approaches, these low-water 
 channels are found filled up, the low-water lied of the river in these 
 shoal places having risen, to be again cut out by the low river. (See 
 Major Suter’s report in Report of Chief Engineers, 1875.) 
 
 At the Horse Tail Bar, below Saint Louis, the bed of the river has 
 been observed to rise 8 or 10 feet above low-water in the interval be¬ 
 tween two low-river periods. (See General Simpson’s report in Chief 
 of Engineer’s report, 1876.) 
 
 If, then, the final effect of a flood which rises from 30 to 50 feet 
 above low-water is to raise the low-water bed of the river at shoal 
 places, may it not be possible that if the height of this flood be some¬ 
 what increased by levees the bed may rise still further instead of being 
 depressed, thus injuring instead of improving navigation ? 
 
 But even if a rise or fall of a foot or two in the bed of the river were 
 produced by levees, it is difficult to see how this would sensibly affect 
 the low-water width of the river. Bad navigation arises from excessive 
 low-water width at certain places, and is to be cured by contracting 
 that low-water width to about 3,000 feet. This contraction must be 
 effected by works in the bed of the river, and not by levees on top of 
 its banks, out of contact with the low-water river. 
 
 For these reasons we are of the opinion that levees are of very little 
 value in improving the low-water navigation of the river. Of their 
 necessity in protecting alluvial lauds against destructive floods there 
 can be no doubt, and to obtain such protection the first step would be 
 the closure of gaps in existing levees. The regulation of the low-water 
 river, including the fixation of the river banks, would be of the great¬ 
 est aid to the levees, since it would secure them from destruction by 
 caving. 
 
 The majority report anticipates as a result of the proposed works a 
 lowering of the flood-level to such an extent “ as will ultimately render 
 the maintenance of the levees as an aid to navigation practically need¬ 
 less above Red River.” 
 
 As to the larger question, whether the proposed works will make 
 levees unnecessary to prevent destructive floods on this part of the 
 river, there are in our opinion no sufficient data for drawing reliable 
 conclusions; theoretically they should in some degree lower the bed. 
 
 A reduction of the flood-level is very desirable, but where on other 
 rivers this has been effected, cut-offs have usually played an essential 
 part. For this reason we are not prepared to absolutely reject their 
 use, after the banks of the river have been thoroughly protected for 
 considerable distances above and below the sites where they are about 
 to occur. 
 
 3. From the lack of sufficient experience, either in this country or 
 abroad, in the improvement of rivers by the means recommended in the 
 report, the estimates of cost can only be considered as rough approxi- 
 
REPORT OF MISSISSIPPI RIVER COMMISSION. 23 
 
 mations, since the strength needed for the works will have to be de¬ 
 termined by trial. For this reason we think it in the interest of economy 
 that works should not in the first year be undertaken at more than one 
 or two of the points for which estimates are submitted. 
 
 C. B. COMSTOCK, 
 
 Major of Engineers and Bvt. Brig. Gen. 
 
 BENJAMIN HABKISON. 
 

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