short annual periods in devastating flow of waters, and that its general characteristics, as compared with other rivers with reference to irrigation, are so abnormal as to require different or more heroic treatment. I therefore projected a scheme which may be briefly outlined as follows: To build a strong dam of stones and cement-say 60 feet high-in the pass before referred to, and by submerging about 60,000 acres of land now subject to overflow and of little comparative value, create a vast lake 15 miles long by 7 wide, with a probable storage capacity of 4,000,000,000 cubic yards of water; place gates on each side of the river in the dam at the 50-foot level for wasteweirs and irrigating canals to supply each side of the river and keep up a flow in its bed which would bring the water in the canals 70 feet above the streets in the cities of El Paso and Juarez, respectively. The gates at the 50-foot level would give an available reserve of water of 10 feet over the entire surface of the lake-over 2,000,000,000 cubic yards which would be exhausted during the long season of little flow for the purposes of irrigation and other needs, as well as maintaining a constant stream in the river beds so arranged as to exhaust the reserve about the period of annual flood, which would be checked and held in reserve for the next season of little flow, and in this manner produce a comparatively constant and unvarying flow of water for each entire year below the dam, redeeming many times the number of acres submerged above in the lake from overflow below, and fixing permanently the national boundary, the banks of the river, as well as the boundaries and titles to private lands, and making it an easy matter to collect duties and prevent smuggling, detect crimes and misdemeanors generally, arrest and punish criminals, as it is along other national boundaries. The assumed flow given for the seventy-five days of high water will give about 6,500,000,000 cubic yards, and that for the remaining two hundred and ninety days 1,500,000,000, making an aggregate annual flow of 8,000,000,000 cubic yards. If we allow 2,000,000,000 of this for loss by evaporation and other wastes, which former in this dry atmosphere is very great, perhaps 80 inches, we have 6,000,000,000 cubic yards remaining. This should be divided into three equal parts, one for each side of the river, for irrigation and other needs, and the third for overflow, through water motors, to furnish power to the future manufacturing cities on each side and to maintain a constant flow in the river below to the Gulf, as would no doubt be demanded by the people there as their right ere they would permit the scheme to be carried out. The 2,000,000,000 cubic yards falling a distance of 50 feet over the dam, estimating the weight of a cubic yard of water at 500 pounds, and 1 horsepower the energy required to lift 33,000 pounds 1 foot in a minute, would expend energy equal to over 10,000 horsepower for eight hours every day in the year, and produce a constant stream in the bed of the river 26 yards wide by 1 foot deep, running with a velocity of 5 miles per hour, to say nothing of the probability that the greater part of the other two-thirds would find its way again to the river bed through the earth and air, the whole flowing in a steady, continuous stream to the mouth of the river, to be used as required at any season of the year, instead of, as is now the case, three-fourths of the entire mass of the annual flow going rapidly to the Gulf in the short period of seventy-five days untaxed. Estimating the amount of water required for annual irrigation at 20 inches, the water reserved for that purpose would be sufficient for 100,000 acres on each side of the river all that could be reclaimed from the desert for 100 miles below. To carry out this project I recommended to the people on each side of the Rio Grande that they petition to the executive authority of their respective nations for the creation of a joint commission to draw up the necessary treaty stipulations to protect the work and the rights of all interested in them, the fundamental feature of which should certainly be that each nation should have the right to divert no more than onethird of the flow at any period, and that one-third of the flow should be maintained in the bed of the river, and that this international commission have charge and control of the work after completion as well as during construction. That the legislative authorities of the two nations be asked to appropriate, after complete investigations and estimates have been made, money sufficient to complete the work, probably $100,000 for the dam proper, $100,000 for the condemnation of the 50,000 acres of land to be submerged, and $100,000 for the removal of some 15 miles of the roadbed of the Atchison, Topeka and Santa Fe Railroad to bluffs above the old bed of the river, where the track now lies, subject to annual damage, and sooner or later total destruction, unless removed. It will also be apparent that the waters of this great lake will be clear and fresh, the silt held in suspension in the current of the river being precipitated as soon as it enters the still water of the lake, doing away with the great trouble and expense now necessary in keeping the canals and ditches cleansed of sedimentary deposits, and a further great benefit derived from using water reduced in temperature by exposure for months in a warm climate far below that used in the early spring, which comes in. three days from snow and ice and is immediately applied to the young and tender sprouting plants, chilling and checking their growth. I know of no point in the Rio Grande between Albuquerque and the Gulf of Mexico where nature has provided both the natural basin and rim for a lake of such great dimensions, for, indeed, it can be made 100 feet deep if desired, and it may be questioned whether a depth of 60 feet, with 10 feet reserve to draw from, will afford sufficient storage to control perfectly the tide at its highest flow. This project was well received by the people and has been earnestly discussed in the public press of the locality ever since with general approbation and a disposition to endeavor to carry it out as quickly as possible. The only question exciting any general distrust is that the sedimentary deposit in the lake, it is held by some, will shorten the life of the reservoir by filling the lake at such an early period as to render the scheme of doubtful expediency, and opinions differ very widely upon this subject, which is, indeed, a problematical one, and can only be determined, even approximately, by actual measurements of a great majority of the annual flow, for the quantity of sediment changes with flow and season. That the bed of the river will eventually be filled, of course, is only a matter of time, but whether in fifteen or one hundred and fifty years can only be ascertained by prolonged, actual measurements; but even if filled in the near future it seems to me that the difficulty may be overcome by raising the dam, unless, indeed, that should be required too often. The matter has already been referred to Major Powell, chief of the Geological Survey, who has sent Capt. Clarence Dutton, of his Department, to El Paso to investigate and report on the feasibility of the scheme; but as the initial steps, should it be pronounced feasible, must come from your Department in the nature of international treaty stipulations, I have thought it proper to thus early acquaint you with the grand project. I beg to refer you to Hon. Mr. Lanham, member of Congress from Texas, who is acquainted with me personally and my projected scheme. ANSON MILLS, Major Tenth Cavalry, Brevet Lieutenant-Colonel, [Extract from Eleventh Annual Report Geological Survey, Part II, pp. 52–57.] RIO GRANDE BASIN. The Rio Grande rises in the mountains of southern Colorado, flows easterly into the great San Luis Valley, then turns southerly into New Mexico, traversing that Territory from north to south. It forms for a few miles the boundary between New Mexico and Texas, and then is the dividing line between Texas and the Republic of Mexico. From Del Norte to the Pecos River in Texas its waters are diverted by hundreds of ditches. Some of these are of great antiquity, dating back to the Spanish conquest, and perhaps earlier. Communities and towns in Colorado, New Mexico, Texas, and in the Mexican Republic are dependent for their life upon the waters of this river, and anything that affects the flow is of vital importance to thousands of people. The diversions of water have proceeded from the south upstream, the Mexicans gradually extending their settlements and taking out small tortuous ditches along the bottom lands. Within the last few years, however, following upon the development of mining in Colorado, agriculture has been found very profitable in the San Luis Valley, and canals as large, if not larger, than those of any other locality in the United States have been built. The enormous diversions of water in this valley and the unusually dry seasons have resulted in a diminished flow in the river below, so that for two summers the bed of the stream has been dry below San Marcial. As a consequence, loss of crops and great suffering have ensued among the farmers who have been accustomed to depend upon the river water. Such a succession of dry years is, of course, likely to occur again, and even if the drought is not so severe, with the continual diversion of water in Colorado and upper New Mexico there must finally come a time when scarcity of water will be the rule in the lower part of the Territory and in Texas and Mexico. The water-storage problem, therefore, is of momentous importance, and a study of all the facts bearing upon hydrography is demanded at once. The investigation of the water supply of the Rio Grande basin was begun by the establishment of river-gauging stations at Del Norte, Colo., at Embudo, N. Mex., and at El Paso, Tex. The tables of monthly discharges for these three places will give the main facts of the water measurements. The total amount of water which passed Del Norte during the year ending June 30, 1890, was 0.23 cubic miles, or an average of 1,090 second-feet for the twelve months. This amount, if distributed uniformly over the drainage basin above the gauging station, would cover the ground to a depth of 10 inches. There are but few small ditches taken out above Del Norte, and no large bodies of level land, so that the results obtained there may be considered as the total discharge unmodified by artificial means. The distance from Del Norte to Embudo by river, omitting the tortuous meanders, is about 130 miles. During this course the river receives many small tributaries, as will be seen by a glance at a map. Many of these, however, at ordinary stages lose all their water by diversion to irrigating ditches, or by its sinking into the sandy beds long before it can reach the trunk stream. Only in times of flood do they actually contribute to the discharge of the river. At Embudo the total discharge (see Pl. LXXIII) for the year was 0.26 cubic mile, or a daily mean of 1,240 second-feet, only 150 second-feet more than at Del Norte. Considering any such point as Embudo, it becomes a difficult matter to compute the drainage area which actually contributes to the flow. As just stated, the rain which falls upon vast areas included in the drainage basin seldom or never reaches the river. In the northern portion of the San Luis Valley the streams flow into the San Luis lakes, from which there is no outlet. All this part of the drainage basin can therefore be excluded at once as not contributing to the Rio Grande. Farther south, however, the difficulty of discriminating between the portions of the basin which do or do not supply water becomes greater, and it is impossible to decide what particular areas should be considered as tributary to the stream. The total area of the basin above Embudo, excluding the drainage into the San Luis lakes, is 7,000 square miles. Distributing the total flow for the year over this area, the depth would be 2.4 inches. The excess of the discharge of Embudo above that of Del Norte, if distributed over the drainage included between Del Norte and Embudo, would cover the ground to a depth of only 0.36 inch. It should be noted that in this comparison no account is taken of the results of the canal diversions. El Paso, according to the survey made by army engineers,' is about 517 miles below Embudo, following the course of the river. The slope ranges from 4 to 52 feet per mile. The principal tributaries are the Chama, Jemez, and Puerco, all coming in from the west. As is shown by the diagram of discharge and monthly averages, the water received from tributaries below Embudo is not sufficient to supply the loss by evaporation and diversion. The total flow for the year at El Paso was 0.22. The capacity of the reservoir is 0.16% of a cubic mile, averaging 1,050 second-feet, or 190 second-feet less than at Embudo. From the latter part of July to the middle of December the water ceased flowing, the bed being dry except in deeper pools. 1 Annual Report Chief of Engineers U. S. A., 1889, p. 1571. The following comparison of the mean daily discharge in second-feet at Embudo and El Paso gives some facts of interest: Mean daily discharge of Rio Grande in second-feet. It is evident that from 300 to 400 second-feet must pass Embudo, in addition to the ordinary discharge of the tributaries, before any water can reach El Paso. SEDIMENT. The sediment observations were begun at Embudo, N. Mex., January 15, 1899, and were continued for three months. The apparatus was then shipped to El Paso, where samples were first taken on July 10, the work being continued from that time through the following fiscal year. In these measurements the object in view was not so much the obtaining of results of scientific accuracy as the procuring of certain data for engineering purposes, viz, the approximate proportion of silt carried by the river water at various stages and seasons. equipment for doing this work was necessarily simple and rather crude, owing to the original requirements that these measurements should be made in camp and that all parts of the apparatus should be strong and portable. The In the previous annual report1 mention is made of the conclusions reached as to the most convenient way of taking samples and drying filtrates. These methods have been in use during the year and give quite satisfactory results. With the sediment trap, a horizontal cylinder with vertical sliding doors at each end, water was taken at about onehalf foot below the surface for the top sample and at about one-half foot above the bottom for the bottom sample. These were then placed in covered jars and allowed to settle for three or four days. At the end of the time the clear water was carefully drawn off with a glass siphon and the sediment washed out upon filter paper my means of a jet of clear water. The filter papers were previously dried and weighed, and after receiving the sediment were again put into the drying oven. This was kept at a temperature of from 50 to 60° C. by an oil stove. After twentyfour hours' drying the papers containing the sediment were carefully weighed, due precautions being taken against increase of weight by absorption of moisture from the air. On the diagram, Pl. LXXIV, are given the data from the El Paso station, showing graphically the number, date, and agreement or lack of agreement of the observations. One, two, or three samples were taken on the same day. As above stated, each sample was, in general, made up of portions taken from near the surface and bottom, being intended to represent the average sediment of that vertical plane. 1Tenth Annual Report U. S. Geol. Surv., Part II, Irrigation, p. 85. |