WSP10867 - Laserfiche WebLink

Home Browse Search

._~ ~'l '\ upon the land is cOrlsumed in plant transpirtation and seepage. The residue, which is a substantial part of the amount diverted, eventua lly finds its way back into the stream. This water, which will pass down the river to Mexico in any event, is supplemented by floodwaters and other excess waters which are used for desilting, canal sluicing, and other purposes. Engineers of the Bureau of Recla- mation and the American section of the Boundary Commission estimate that, when full development has been reached in the United States, these return flows will be not less than 900,000 acre-feet a year, and perhaps as much as 1, 125,000 acre-feet a year, thus limiting the draft on what might be called firm water upstream to a quantity somewhat less than 600,000 acre-feet a year, and perhaps as little as 375,000 acre-feet a year. While the California witnesses have testified that they believe these estimates of return flow to be too high, the committee believes that greater weight should be given the estimates of the Federal agencies, who have made long and care- ful studies of this problem and who are considered to be disinterested witnGsses. According to all the testimony, the average annual virgin run-off from the Colorado River Basin is approximately 18,000,000 acre-feet a year. "The amount allocated to Mexico is thus only about 8 percent of the total supply, and the amount of firm water--that is, water which must be released from storage at Davis Dam--which will ultimately be required, in addition to return flows which will be in the river in any event, is only 3 percent or less, of the total annual supply. The balance remaining for use in the United States, or approximately 16,500,000 acre-feet on the average, will permit of a tota 1 development in the United States almost treble the present development. That is to say, the United States is now USing only a little over a third of the water which is made available for her use under-the-trea ty~-Mexi=.,-OI'l-the-other-ha oo.,-i S-110W-U sing-approxi-- mately 1,800,000 acre-feet a year, and in the meantime some B, 000,000 or 9,000,000 acre-feet of water flows through Mexican territory and wastes unused into the Gulf of California. The testi- mony is that it will be many years hence before this water can all be put to beneficia! use in the United States. If and when that time arrives, present Mexican uses must be curtailed. Thus, by placing for all time a limit, measurably below present Mexican diversions, upon the obligation of the United States to supply Colorado River water to Mexico, the treaty provides needed assur- ance to American agencies and communities in planning future developments. " And on pages 6 and 7: "The committee is unqualifiedly of the opinion that the language of articles 10 and 11 of the treaty is clear and subject to no other -2-