Popular Science Monthly/Volume 73/July 1908/The Mississippi River Problem
| THE MISSISSIPPI RIVER PROBLEM |
By WALTER SHELDON TOWER, Ph.D.
UNIVERSITY OF PENNSYLVANIA
THE project for a deep waterway from the Great Lakes to the Gulf has been dreamed about and discussed intermittently for half a century, but nothing definite ever came of it until a little over a year ago, when, from a conference held at St. Louis, there was born the permanent organization called the "Lakes to the Gulf Deep Waterways Association." That this concerted movement came at the psychological moment has been indicated by subsequent events. Last winter the Rivers and Harbors Congress in session at Washington supported the project. The president in his Memphis address heartily endorsed the enterprise; shortly afterward his annual message called attention to the need for river improvement and the question is now in the hands of congress with some definite action sure to come in the near future.
Within the last decade, this country has entered three fields of government activity, forest conservation, reclamation of arid and swamp lands and the building of the Isthmian Canal, the far-reaching results of which can scarcely be estimated at this time. The development of a ship channel through the Mississippi Valley, with feeding lines in the larger tributaries, would likewise be of such tremendous importance to the economic progress of the country that it must be ranked second to none in the list of great national policies.
A few simple statements of fact furnish striking evidence of the need for such a waterway. The drainage basin of the Mississippi system covers an area of approximately a million and a quarter square miles, or rather more than two fifths of the United States proper. This two fifths of the country is the real heart and soul of the nation's prosperity. With its development the United States has not only become independent of the rest of the world, but also has risen with tremendous strides to stand as the greatest producer of food-stuffs that the world ever has seen or ever will see. More than half the total population of the country to-day is found in the score of states bordering directly on the navigable portions of the Mississippi system. As the population increases the most rapid growth must be in these same states, until a century hence with hundreds of millions of people living between the slopes of the Alleghenies and the Rockies, there will exist in the Mississippi Valley the highest and most permanent type of civilization in the history of man. Three fourths of the world's cotton crop is raised in the United States, and the heart of the cotton belt must for all time lie in Mississippi, Louisiana and Texas. Our corn crop is three times as great as for the rest of the world combined, and, though corn is widely grown both north and south, the chief corn belt naturally centers in the Upper Mississippi and Ohio Valleys. For example, five states, Illinois, Iowa, Kansas, Nebraska and Missouri, raise over half the total for the country, or, astounding as it may seem, nearly 40 per cent, of the entire world's crop. Wheat, cattle, hogs, vast quantities of oats, hay, potatoes, lumber, coal and other mineral products come mainly from the Mississippi Valley, each one in point of quantity leading all other nations of the world, and yet no one denies that the limit of productivity is far from being reached. Out of this list, cotton, meat products and bread-stuffs make up a large part of our foreign commerce, with half the world's mileage of railroads required to get the products to the seaports. As might be expected, by far the thickest railroad net is in the Mississippi Valley, yet the roads there have found their facilities increasingly inadequate to handle the produce of the region. "Shortage of cars" has become a familiar complaint in the wheat fields of the northwest. Corn and cotton in the states along the Mississippi have been kept out of the markets because of increased rates on rail shipments. On every side the farmers have raised the cry, "Better freight facilities," but the railroads have steadily failed to meet the demand. Conditions have gone from bad to worse until now the harassed producers see that their only salvation lies in the development of the routes so bountifully supplied by nature, with coordination of rail and water facilities to prevent disastrous opposition.
It is not a case of providing merely enough to meet present needs, for the growth of this vast interior storehouse still continues with gigantic strides. Irrigation, dry farming, swamp drainage, and the exploration of the whole world to give new crop species, are opening every year areas which have heretofore produced little or nothing, while crop improvement and intelligent soil management are adding millions of bushels to the yield of the older regions. Marked by developments unparalleled in the history of the world, there seems to be no limit to the enormous capacity to produce over areas measured in tens of thousands of square miles, areas whose crops alone determine panic or prosperity for the entire nation; areas wherein lie the sinews of the greatest and most stable world power in all history. Not England, nor Russia, nor China, not any other nation or continent of the world, can equal in all its territory the unbounded natural advantages of the Mississippi Basin. Yet with each added harvest the pinch of traffic congestion and heavy transportation charges are felt by an increasing proportion of the population, and as long as such conditions continue the full economic development of the region must be seriously hampered.
The logical solution of all the difficulties lies clearly enough in the utilization of the great arterial system of waterways afforded by the Mississippi and its tributaries. The time was when these rivers were the life currents of the region. In the days when river craft plied the Mississippi, Missouri and Ohio are found the conditions which gave birth to, and stimulated the growth of, St. Louis, Cincinnati, Louisville, Memphis, St. Joseph, Kansas City, Omaha and a host of other river cities of all sizes. To-day these cities are railroad centers, but by that very fact of having ready-made terminals the development of the water route takes on added value. Take, for example, St. Paul and Minneapolis, at the head of navigation on the Upper Mississippi, the greatest flour-milling centers in the world, shippers of hundreds of thousands of tons for both home and foreign markets and at the same time the logical railroad centers for a large section of our own northwest and Canada. Kansas City, almost in the geographical center of the country and undoubtedly destined to become one of the greatest inland cities of the continent, with St. Joseph, Omaha and Sioux City, all lie in the range of former navigation on the Missouri and stand as important shipping centers for the great corn, wheat and cattle trade of the country back of them. The vast quantities of products handled at these places are mainly bulky goods which do not suffer seriously from relatively slow transit, but which do need most urgently the means of getting to market at the lowest possible transportation charge. No better illustration of the advantage of shipment by water can be found than that afforded by the coal trade from Pittsburg to points on the Mississippi. Coal can be sent from Pittsburg to New Orleans by river, 2,000 miles, for about 75 cents a ton, while the rate by rail to Memphis, 807 miles, is over $3 per ton. On the basis of the charge per ton per mile, the latter rate is about ten times as heavy as the former, a fact which becomes strikingly significant when it is considered that a saving of a single mill per ton mile means $1,000 saved on every shipment of 1,000 tons going 1,000 miles. A similar saving on a comparatively small part of the annual cereal crop alone in those states bordering the Mississippi system would very soon reach a total surprisingly close to the entire cost of improving the navigation.
A waterway with a depth of fourteen feet from New Orleans to Chicago, with channels of less depth in the Ohio and Missouri, would almost unquestionably solve the problem of traffic congestion and high freight rates for a great area of the productive west. It would be a movement directly in line with the policies of various European nations, where far less valuable waterways in thickly settled districts have been utilized most profitably. It is an enterprise which the United States must inevitably undertake sooner or later as the density of population increases throughout the Mississippi Valley. Railroads, thoroughly equipped, yet inadequate to meet the conditions of the present time, will be relatively less able to cope with the rapidly growing demands for transportation facilities in the future. Already in the more densely populated portions of the country waterways once abandoned are being rehabilitated. The country can not long afford to ignore the possibilities presented by the development of the greatest natural highway in the world—the Mississippi and its navigable tributaries. It can not be denied that the improvement of our greatest inland waterways will be followed by vastly more important industrial and commercial advantages than can ever result from the opening of the Panama Canal. These advantages would be not to the people of the Mississippi Valley alone, but to the people of every county and corner of the Union through their dependence on the products of this region.
The project, however, is not at all simple—it is an undertaking fraught with problems which, unless met rightly at the start, must inevitably defeat the entire purpose of improvement. Like all big rivers, the Mississippi and its tributaries have bad habits, the worst of which are devastating floods, followed by very low stages of water at other times; rapid changes in the course through sapping of the banks; and constant shifting of the channel, often over night, on account of the formation of sand bars. In these respects our rivers are not necessarily any worse than others, in fact, they are not so bad as many of the great rivers of the world, but the correction of these habits becomes an unavoidable and serious question when efficient improvement for navigation is undertaken. The question of river control and improvement is most intimately connected with forestry, farming, mining and other industries, since they in many cases largely determine the particular problems with which man must deal. In the Ohio the overwhelming spring floods and low water stages of summer are the chief difficulties, with slack water dams doing much to remedy the latter condition and make navigation possible at all times. The sand-bar evil in the Missouri is so great and so perplexing that it completely overshadows the question of flood control and sapping of banks, which are in themselves of no slight importance. Along the lower Mississippi from St. Louis to the Gulf all three problems urgently demand attention, since this portion of the river represents the trunk line of the entire deep waterways system; and it is just here that the physical conditions surrounding the river make correction or control the most difficult.
From St. Louis southward, the river course follows a broad alluvial plain, which gradually increases in width to about 100 miles near the Gulf. This broad river flat is composed of a soft, highly-productive soil, fine-grained and of indefinite depth, in which the river has developed such a tortuous course that while the air-line distance from Cairo to the Gulf is about six hundred miles, the journey by water is twice as long. On every one of the many turns and bends throughout the whole twelve hundred miles the river is constantly undermining and wearing away the outer bank of the channel in just the same way as the outer rail of a curve on a railroad is worn rapidly and must soon be replaced. The fine-grained, loose character of the soil greatly facilitates the undermining action, especially during the irresistible rush of flood waters.
This habit of eating away its banks is perhaps the worst which can be charged against the lower Mississippi, and presents one of the most serious problems in the whole question of control. Needless to say the unceasing changing of the course is vitally important to the plantation owner, who sees his fertile land steadily vanishing, often at the rate of 300, 400 or more feet a year along his entire water front. It is still more important to the towns and shipping points located along the river. New Orleans is the only big city located directly on the river flat, and, fortunately for the city, it is at a place where the river's course is now comparatively straight. Other cities, like Memphis, Vicksburg and Natchez, are located on the high bluff where the river swings close against the eastern side of its valley. These latter towns have secured immunity from floods, but even simple changes in the channel would deprive them completely of their water fronts and strike fatal blows at their prosperity.
Even the present extent of the river traffic demands that there shall be more or less villages directly along the river and steamboat landings at various points, but every one of these places enjoys only a temporary existence. Since the river current hugs close along the outer side of every curve in its course, it follows that the deepest water, and hence the main channel, also lies near the outer bank. The natural result is that all steamboat landings and all important shipping points must be located on the outer banks of curves, as is found to be the case all along the river. The difficulty which lies therein is obvious enough, for with rapid undermining of the outer bank of all bends, the river is always tending to destroy the water front of every place so situated. The history of the landings below Cairo shows that practically every one of them has been driven back before the advancing river at the rate of 100 to 150 feet a year for the last quarter of a century.
That this condition is felt on a larger scale than by mere landings is shown by the case of Greenville, Mississippi. This city of nearly 8,000 people, the largest river port between Vicksburg and Memphis, is the flourishing commercial center for an important part of the lower valley, yet imminent ruin is even now staring it in the face. Greenville stands on the outer bank of a great curve in the river with three other curves up-stream from it. Narrow necks of land separate the different curves, and these necks are rapidly disappearing as the banks cave in. Twenty-five years ago at the curve farthest up-stream from the city the neck was over 4,000 feet wide, five years ago it was less than half that width and was caving badly. The neck below the city is only half a mile wide and is also yielding rapidly to the attacks of the river. Greenville is confronted with these alternatives: If the neck below the city is cut through first by continued sapping, the city will be left high and dry, five miles from the river and its reason for existing will be gone. If, on the contrary, the neck above the city is the first to succumb, the resulting changes in the channel will cause most vigorous scouring of the bank exactly where Greenville stands and it will be speedily swept away. The levee now stands where the main street once ran and, despite every effort to stop it, the town has been forced to play leap frog over itself to keep away from the advancing river. Through the expenditure of a million dollars in protective devices the crisis has been delayed, yet the city is doomed eventually, and the money spent in its protection must be regarded as wasted.
St. Joseph, Missouri, with a population exceeding 100,000, and one of the most important centers of the west, faces a somewhat similar fate from the Missouri river. Opposite the city the stream swings around a great bend, St. Joseph being located on the bluff above the river bottoms. Some smaller villages on the flat have already been swallowed up in the stream, and, at its present rate, the current will soon cut its way through the narrow neck which lies a few miles west of the city, severing the Grand Island railroad, rendering the big steel bridges at St. Joseph practically useless, making new bridges over the new channel necessary, cutting off the intake of the water supply, and leaving the city without any outlet for its sewer system. Here, again, somewhat over a million dollars has been spent in river work above and below the city, but the banks have continued to cave, and St. Joseph is facing the prospect of being left higher and dryer than Greenville. From the standpoint of transportation by water, however, the loss of the river front at St. Joseph would not now be a serious calamity, since the Missouri route is at present rendered quite useless by the excessive formation of sand bars.
Both the federal government and the Chicago and Alton railroad have spent large sums in an attempt to control the Missouri at Glasgow. Kaskaskia, the one-time capital of Illinois, has been wiped out of existence by the changing current of the Mississippi, while the prospect of a cut-off at Cowpen Bend, above Natchez, indicates that the harbor of that city will be destroyel by the deposition of large quantities of sand along the entire water front. Striking as these individual cases may be in themselves, the question of this cutting away of the banks, accompanied by deposition of sand in other places, takes on far greater significance as soon as costly improvements are suggested. It is undeniable that what is happening along the river to-day is a true sample of what the river may be expected to do every day as long as the existing conditions prevail. A fourteen-foot channel presupposes important movements of goods from many points along the river. Large shipments can not be handled readily or economically without expensive modern terminal facilities along the river front, but the building of such terminal facilities can not be expected as long as they are threatened with the same fates as now confront Greenville, Natchez and St. Joseph.
The flood evil, the second great problem to be met in the control and improvement of the Mississippi system, has been fresh in the minds of every one since the disastrous spring of 1903, when the loss of property amounted to fifty or sixty million dollars. The flood problem applies not only to the main Mississippi itself, but perhaps even more vitally to its chief tributaries, the Missouri and Ohio, which must be regarded as the main feeders to any proposed improvement. The total loss from a few historic floods in these streams has been tremendous. In 1881 and 1882 the floods of the Ohio and lower Mississippi caused a loss of $15,000,000. In 1881 the Ohio Valley alone suffered to the extent of $10,000,000. An area twice the size of New Jersey was laid waste along the lower Mississippi in the spring of 1897 with losses again reckoned in tens of millions of dollars. The unprecedented ravages of the Missouri came in May and June of 1903, and finally this last year saw damage to an extent estimated at not less than $100,000,000 in the Ohio Valley. In the last quarter of a century, therefore, the plain money loss from a single half-dozen floods approaches a quarter of a billion dollars, while the sum total from all floods must be acknowledged to equal many times over the entire cost of the most effective and permanent means of protection.
The principal cause of the floods in the Mississippi is heavy or prolonged rains at certain seasons of the year, a primal cause, which lies beyond the power of man to control, but which has been greatly aided in its effects by wide spread deforestation about the head waters. Flood conditions vary widely in the different tributaries. The Missouri has the largest drainage basin of any of the tributaries, about 540,000 square miles, but the average rainfall over the region is small, unusually heavy and long-continued rains are less frequent, and, because of porous soils and excessive evaporation, only a small part of the rainfall passes off in surface drainage. As a result of these conditions, the Missouri supplies only about one seventh the total discharge of the Mississippi, and is, on the whole, as regards floods, the least important of the large tributaries. The upper Mississippi, with a drainage area only a third as large as that of the Missouri, turns in about one fifth the total volume of the main stream, while the Ohio, draining approximately 200,000 square miles, sends down a third of all the water discharged by the Mississippi. These three rivers, therefore, yield over 60 per cent, of the gross volume, the remainder being divided between the White, Arkansas, St. Francis, Yazoo and Red rivers, which join the main stream too near the mouth to be important factors in the production of severe floods.
The Ohio is, on the whole, much the worst flood offender, partly because of its normally greater volume, and partly because of the conditions existing in the region it drains. The major portion of the areas drained by the Missouri and the upper Mississippi are distinctly less rugged than the Ohio basin, and over both areas the heaviest rainfall, coming in May and June, arrives at a season when the soil can take a large percentage of it. The largest tributaries of the Ohio, on the contrary, in etching their valleys in the surface of the Allegheny plateau, have produced the steepest and most rugged parts of the whole Appalachian region. Here the heaviest rainfall comes in January, February and March. Add to these factors the frequent complications of melting snow and frozen ground, which sheds water like a house roof, a district largely deforested, and the enormous destruction by sudden rising of the Ohio is explained. It is truly fortunate that by the provisions of nature the three rivers, the Ohio, the Mississippi and the Missouri, have never been known, and probably never will be known, to be in extreme flood at the same time. Such an unhappy coincidence of high stages, if it came about, would quite certainly mean total obliteration for everything in the lower valley.
The flood evil is in a large way the underlying cause of most of the trouble in the Mississippi. At time of flood, the erosive power of the river is increased a hundredfold, caving of the banks is often excessive, levees situated rods from the channel before the flood and apparently safe are undermined, and the narrowing of necks between bends is greatly accelerated or quickly accomplished. Much of the damage from floods must be laid to the cavings of banks by which landings are destroyed and whole plantations are soon swept away, while through breaks in the undermined levees the raging waters sweep over the surrounding country. This spread of the flood is fostered by the fact that the river channel lies above the surrounding bottom lands. To the naked eye the region appears absolutely level, but from the river the broad plain slopes away at a rate varying from four to thirteen feet per mile. Once outside its channel, therefore, the water finds a natural course down hill into every part of the back country, carrying destruction wherever it goes. Unfortunately, this character of the river can not be altered; on the contrary, the more the river is confined between artificial levees and restricted in the area over which it is free to spread, the greater will be the devastation whenever a flood does occcur, so that with the extension of the levee system the occurrence of floods becomes an increasingly serious problem. The recognition of this fact can not be urged too strongly, for until the flood waters are under absolute control, the construction of a deep channel, no matter whether it be in the river itself or in the form of a canal along the stream, must be clone in the face of constant danger of having the entire system crippled and large portions destroyed whenever overflow takes place.
Again, when the river is in flood, as it is to a certain degree every year, it is carrying along the greatest amount of sediment, much of which represents the most fertile part of the soil. The total amount so carried is almost beyond conception, but to carry it by freight train would require 500 trains for every working-day in the year, each train consisting of fifty cars with a capacity of fifty tons. Besides this tremendous quantity poured out into the Gulf every year, other incalculable masses are deposited as bars all along the course, and as the water falls to its normal level these bars are a constant menace to every form of navigation. The presence of these obstructions and their rapid shifting from day to day has always been one of the most serious handicaps to river transportation. In fact, the abandonment of navigation on the Missouri may be laid entirely to the utter inability to cope with the shifting sands. Deforestation, cultivation of the land especially, and mining operations, are vitally important in the question of soil washing, surface erosion and the amount of sediment in the streams.
The project for a deep waterway for commercial purposes, therefore, is confronted with these serious problems which must be solved before the government can afford to spend one or two hundred million dollars in river improvement. Some system of control must be devised to insure to water fronts and terminal facilities a reasonable degree of permanency through protection against erosion of the banks. There must be some way of checking disastrous floods which would in a single season, and perhaps year after year, destroy improvements costing millions of dollars—as the experience of some of the eastern canalized rivers indicates. The prevention of low-water stages is no less important, since marked variations in the water level make it difficult to establish the necessary terminal facilities. Finally, the formation of sand bars must be stopped, otherwise it means stupendous, unending and probably ineffective, dredging operations in an attempt to keep the channel open.
If the Missouri could be removed from the list of tributaries by giving it a separate mouth, the sand-bar problem would no longer exist, since that stream contributes over 60 per cent, of the total brought into the Mississippi. Eeducing the load by 60 per cent, would certainly mean that the Mississippi could then keep its own channel clear. But the idea of providing a separate course for the Missouri from St. Louis to the Gulf is too daring even to be suggested. Moreover, it would remove from the immediate benefit of the deep waterways project those important communities which hope for renewed navigation on the Missouri.
If the entire lower Mississippi were given a new course free from sharp bends, as could be done readily by cutting through the successive necks, the sapping and caving of banks would cease and the distance from St. Louis to New Orleans would be lessened nearly by half. That this plan is entirely feasible is amply demonstrated by the success of the Germans in correcting and straightening the Rhine. The Rhine, if possible, presented a more difficult problem than does the Mississippi, but the German engineers recognized the fact that where sharp bends exist it is impossible to prevent entirely undermining and caving of the banks. Acting on this principle, it was decided to give the river a practically new course, less winding than the former, and in which future control is insured. Unfortunately, this procedure applied to the Mississippi would not be an adequate remedy for the floods, nor would it effectively prevent the formation of sand bars. It is unquestioned, however, that the flood stages would run off more rapidly and a greater amount of sand would be scoured from the channel, since in a shortened course the river would have a steeper descent and consequently a more rapid flow with increased carrying power. The corrected course undeniably has much to recommend it, aside from the mere facts of feasibility and a shorter route.
If the high-water stages of floods could be prevented and the flow of the river controlled, the practical solution of the question would be at hand, for the major part of the sediment is washed into the streams incident to the flood time, and the excessive flood volume causes most of the caving of banks. For a good many years the federal government has been at work on the Mississippi, building levees to control or prevent floods, placing revetments along the banks to check the caving action, and operating powerful sand pumps to remove the shifting bars. It is estimated that in the last forty years the government has spent all of $225,000,000 on the Mississippi and its more important tributaries, not a single dollar of which has gone toward permanent improvement, except in the case of the jetties at the mouth, the slack water dams on the Ohio and the removal of rock ledges at a few points. Fifty million dollars of the total amount has gone into the construction of some 1,400 miles of levees and revetments along the lower course, but before the national government undertook the task of control, the states of Mississippi, Louisiana and Arkansas had already spent not less than $40,000,000 toward the same end. Enough similar work has been done at one time or another by private individuals, so that, first and last, the levee-revetment system to date represents an outlay of fully $100,000,000. Yet not one cent has been devoted to the control of the excessive floods which come almost every year in some of the tributaries, simply because the levee method can not be applied there. It must be admitted that the levee system affords fairly efficient protection from ordinary floods, in so far as damage from overflow in the lower valley is concerned, but its desirability is seriously impaired by the fact that the levees must be constantly replaced. Just as long as the river is allowed to swing against its banks the soft alluvial soil will continue to cave in; levees originally built back from the channel are eventually undermined, rendered useless, and then in cases of high water stages, unless a second line of levees exists, the entire region is open to devastation. Until the sapping action of the river is under control there can be no such thing as a system of levees built once for all. Even the most optimistic advocates of this plan do not claim more than twenty to thirty years for the life of any levee.
It is undeniable that the army engineers in charge of the work have accomplished much in saving large areas from annual inundation, but they have not to any extent permanently improved the river as a highway of commerce. Furthermore, they have signally failed in the attempts to stop erosion of the banks, for past experience shows that no style of revetment yet devised will offer more than partial or brief protection from that action. In fifteen years some landings have been forced back more than a mile, and at important points where careful revetting has been done the retreat is said to have exceeded 1,000 feet. The levee-revetment system as now practised may be the simplest way of protecting agricultural interests on the river flats, but it is certainly not the most economical in the end, nor does it in any way afford even a temporary solution of the great problems confronting navigation and river commerce. The heavy expense of maintenance must go on without end until the sum total of expenditure will aggregate vastly more than the cost of the proper, permanent remedy. The most serious of all the shortcomings charged against present methods, however, is that they do not strike at the root of the evils. The place to control floods is where they originate, in the tributaries, and thus protect both tributary and main valleys; as well try to fight fires by blowing away the smoke as to control the floods by levees along the lower course. To improve the river to the extent of a fourteen-foot channel to St. Louis would be a foolish waste of money as long as the levee-revetment system is the chief method of control.
Various other methods of control have been suggested from time to time, but most of them do not appear feasible or to offer the desired results. The rearrangement of tributaries, either by diversion or by addition, has been advocated, since the addition of tributaries to the Po very materially lessened the flood evil, the increased volume and velocity having caused a marked deepening and widening of the channel. In the Mississippi case, however, there are no important streams which could be added, and the only possible source of increased volume is by giving the Great Lakes an artificial outlet by way of the Illinois River. A certain amount of diversion or rearrangement of tributaries would be possible, though not very practicable, as in getting rid of the load of sediment from the Missouri, or in turning the Tennessee through the Big Hatchie River to reduce the Ohio floods. But in all of these radical schemes the possible benefits to be derived are far outweighed by the inevitable difficulties and disadvantages. It is unquestioned that the tributary system must remain as it is now.
The construction of artificial outlet channels to take off the excess volumes which produce floods has been suggested many times, and it seems likely that if constructed in sufficient numbers they would prove effective. There would, however, always be great difficulty in keeping the outlets sufficiently free from sand so that their usefulness should remain unimpaired. A second and more serious objection to the outlet scheme is that in the lower valley, where the flood control is most difficult and the flood damage most wide-spread, the outlets would have to be provided by turning the water over the low-lying bottom lands. Outlet reservoirs could not be maintained because of the sand and mud with which they would be speedily filled. Under such conditions, therefore, the outlet plan clearly defeats one of the chief objects of flood control—the protection of rich plantations covering thousands of square miles on the river bottoms.
The solution by building a series of reservoirs in the head-waters 'of the chief tributaries appears to be the cheapest and most certain remedy for all these difficulties. By the construction of reservoirs the excess of water which produces flood stages could be impounded and held up with these important results: excessive and destructive high-water stages could not occur, while, on the other hand, by regulating the discharge from the reservoirs, a more even flow of water could be maintained at all times, eliminating to a large degree the losses from diminished water supply, reduced power and fouling of streams incident to the low stages of late summer and early autumn. As soon as the irresistible rush of flood waters is stopped the sapping and caving of banks will be reduced to a minimum, with the efficiency of revetments increased many fold; finally, cutting down the flood volumes means a great diminution of the amount of sediment carried, and a marked alleviation of the sand-bar evil. The reservoirs would, moreover, eliminate floods from the whole system, not merely from the lower course. The prevention of the annual flood damage in the Ohio would in itself be worth the entire cost of the reservoirs, yet until the work of control is carried to the headwaters no relief can be secured for that populous valley.
The solution by head-water reservoirs, of all proposed plans, has probably provoked the most discussion—on the one side, those who regard it as impossible, or, at least, highly impracticable; on the other side, those who consider that it is not only feasible but at once the only proper remedy. It is admitted by every one that the topography of the country about the head-waters of the Mississippi system is especially well adapted to the construction of retention dams and reservoirs. The arguments advanced against this plan, though admitting this condition of favorable topography, maintain that sufficiently large reservoirs could not be constructed and made safe or, in other words, they would, through danger of bursting, be a constant menace to the whole valley below the retaining dam. Again it is argued that if this plan were adopted, the building of reservoirs would have to be done on an enormous scale, since destructive floods often result from local conditions, such as a swollen tributary superimposed on an already swollen river. This necessity for a widely extended system of reservoirs, it is further claimed, would involve such tremendous expense as to make the adoption of the plan impossible. Most of these supposed objections are still based on a report made to congress nearly fifty years ago, and, whether good or bad arguments then, there is no question that they do not apply now.
It is flying in the face of cold facts to contend any longer that reservoirs to retain the flood waters can not be built, or not without danger to the entire valley below. The Ohio floods of 1907, the most disastrous for more than two decades, were due to an excess of water estimated at 23,000,000,000 cubic feet. To hold every drop of that excess discharge would have required a reservoir only a little more than half as big as the Pathfinder irrigation storage reservoir on the North Platte River in Wyoming, or one third of the size of the reservoir in the Salt River project in Arizona. The Engle dam on the Rio Grande, a hundred miles north of El Paso, Texas, will impound about 120,000,000,000 cubic feet of water, equal to one sixtieth of the total annual discharge of the entire Mississippi system, or more than five times the quantity of water causing the most destructive Ohio flood in a score of years. These reservoirs are being built by the government at a cost of about $4,000,000 for the Pathfinder dam, $5,300,000 for the Salt River project and $7,200,000 for the Rio Grande reservoir. Furthermore, it is expressly stated by the Reclamation Service that the Wyoming reservoir and the Engle dam will absolutely control the worst floods which the North Platte and the Rio Grande have ever known, the latter of these streams having been a notorious offender in flood damage. The mere fact of being able to retain the flood waters in impounding reservoirs can no longer be denied, nor can the claim of danger from breaking dams be now advanced as a valid argument against this system. This government is most assuredly not spending millions in reclamation projects and encouraging thousands of people to take up irrigated lands if there is any remote likelihood of having homes, property and lives wiped out in floods from bursting reservoirs.
Granting, then, that the reservoirs are feasible, there still remains the question of expense in constructing the number necessary to place one or more in each of the most important tributaries. Estimate the expense most generously, letting each one cost a third more than the Engle dam above El Paso, and the total figure then is less than what has already been spent on the Mississippi system. But there is another important factor to be considered—the tremendous possibilities which lie in the development of water power from each reservoir. The question of future motive power for industrial purposes, as the coal supply decreases, is a problem which must soon be met in this country, and probably will be solved by the use of water power either directly or through electricity. In fact, even now, water rights are being rapidly acquired and developed on every hand, as the advance guard of the change that is to come. A sample of what a storage reservoir will do can be seen in the case of the comparatively small irrigation project at Minidoka, Idaho, which will develop about 30,000 horse power per year. Renting this power at the very low figure of $10 per horse power per year would pay for the entire Minidoka project, reservoir, irrigation-canals, gates and all, in six years. The amount of power generated by the Mississippi system is variously estimated high and low, with 60,000,000 horse power per year as an intermediate figure. Much of this amount is not directly available, but granting on a conservative basis that a series of impounding reservoirs would develop immediately 2 per cent, of that amount, there would be 1,200,000 horse power to be turned into electricity and distributed to factories. A purely nominal rental would be ample enough to repay in two or three decades the entire original expense of the system, besides a good income on the investment. The reservoir system, however, must be intimately associated with forest conservation as a vital factor in regulating surface drainage and in checking the amount of soil erosion which supplies sediment to the river.
The proper building of reservoirs in the headwaters, therefore, offers what no other plan can possibly offer: it promises effective regulation of river stages and water supply for all time to come, removing entirely the liability of destructive floods, checking the erosion of banks and preventing much of the formation and shifting of sand bars and the pollution of water which the presence of sediment means. At the same time it provides a way of actually paying for itself in short order, aside from all idea of the savings to shippers and river interests in general which would be in excess of the cost. The importance of this latter consideration is emphasized best by a brief comparison with the system now being followed. The levee-revetment system, as mapped out, calls for an expenditure of $60,000,000 for its completion. From the engineers themselves comes the statement that the average life of a levee is not over twenty years, which means this and no more: in two-score years, at the most liberal estimate, the present system, completed, will have disappeared entirely and a new series of levees constructed at the cost of another $60,000,000 will have taken its place, with conditions then no better than they are now. Considered solely on their own merits from the standpoint of control afforded, the present system has nothing, and the reservoir plan has everything, to recommend it.
In order to bring the river route to its highest possible degree of efficiency, it would be necessary to combine the reservoir system with a straightened course for the lower river, by which combination every evil would be removed and absolute control for all time would be insured. The reservoirs would make it possible to regulate the flow of the streams, preventing both floods and very low water, and at the same time, through developed horse power, pay for the improvements. The corrected or straightened course would shorten the route and effectively put an end to caving of the banks with all the difficulties arising from it at present. Together the reservoirs, with the necessary forest conservation and corrected course, would remove the sand bar problem—the one greatly lessening the actual amount of sand carried into the river, the other giving the current increased power to sweep its own channel clean.
It is undeniable that this plan calls for a large expenditure for its completion, but in the long run so does the levee-revetment system, without anything tangible to show for the outlay in the end. The whole question narrows itself down to a single issue: whether it is not better policy to do the right thing at the start, even if it require great initial outlay, rather than follow a plan which means the reconstruction of part of the so-called improvements every decade for centuries, with the region concerned always chafing under the handicap of a mediocre, inadequate waterway and-suffering heavy annual losses from uncontrollable floods. The waste of money on levees and revetments ought to cease once for all. Let the federal government authorize the completion of the entire reservoir system with a straightened course for the lower river, and loose the bonds which every year are drawn tighter over this heart of our nation.