EBBITT HOUSE, Washington, D. C., December 10, 1888. SIR: Agreeable to promise at our interview this a.m., I have the honor to submit the following general outline of my projected scheme for an international dam and water storage in the Rio Grande River, near El Paso, Tex., for the control of the annual floods and the preservation of the national boundary to the Gulf, and for other purposes. The Rio Grande, 1,800 miles long, rises from an unusual number of tributaries in the very high altitudes of southern Colorado and northern New Mexico, where the rain and snowfall is extraordinary, and the ice formed therefrom in the long winter enormous. As it flows southward the precipitation gradually decreases for 600 miles, when the Mexican boundary is reached at El Paso, Tex., where there is neither snow nor ice, and but 8 inches annual rainfall; from thence 1,200 miles south to the Gulf of Mexico the rainfall is only sufficient to compensate for the loss by evaporation (which latter is very great), and for these reasons the river has but few tributaries and no increase of flow below El Paso. The annual floods, caused by the melting of snow and ice in the mountains, take place in May and last for about seventy-five days, during which period the average flow may be estimated at 200 yards in width by 2 yards in depth, with a velocity of 5 miles per hour, although in recurring periods of about seven years it is much greater. During the remaining two hundred and ninety days of the year the average flow is perhaps not over 30 yards wide by 1 yard deep, with the same velocity; and in the same recurring periods, in the intervals between the high tides, the river goes dry for months, as it is at this time--or at least has no current, with not enough water in the pools to float the fish. There is at present popular opinion that this want of water comes from its diversion by the numerous irrigating canals lately taken out in Colorado and New Mexico, and while it is problematical what effect this may have, if any, I am of the opinion that most of this water returns to the stream again, either through the atmosphere, by evaporation and precipitation, or by the earth, through overflow and drainage, as from personal observation I know that these seasons of flood and drought were of about the same character thirty years ago. After leaving the mountains the river passes through low valleys of bottom lands from 1 to 12 miles wide and from 4 to 8 feet above low-water level, of a light, sandy alluvium formed during annual overflows by sedimentary deposits from silt, which the water always carries in a greater or less degree.