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Show APPENDIX VI VI-35 30 COLORADO RIVER STORAGE PROJECT increasing. There is, of course, a relationship between the extent of upper basin uses and the availability of water to the lower basin. fJhe studies performed by the engineering groups assumed releases at Hoover of 7.5 million acre-feet by the upper basin group, as well as assumptions by both groups of 8.5 million acre-feet in 1902, increasing to 9.3 million acre-feet in 1970 and remaining constant thereafter. What releases for these purposes may be in the future are matters of judgment. All aspects considered, it seems to us that they may be expected to range from 8.2 to 8.5 million acre-feet per year during the filling period. To be noted is the proposal to hold the scheduled delivery under the Mexican Treaty to 1.5 million acre-feet per year. This is the Mexican Treaty obligation. It serves to put the Mexican users on notice that during this period there likely will not be any water whereby the scheduled delivery could reach 1.7 million acre-feet per year which is permissible under the treaty on an "if available" basis. Paragraph 4 is similar in content to paragraph 3 in that it repeats the principle that uses of water for consumptive purposes will be met but the paragraph applies to the reach of the river between Glen Canyon Dam and Lake Mead and to the use of water directly out of Lake Mead. It is necessary to separate the uses between Glen Canyon and the upper end of Lake Mead from those which are or might be made directly out of Lake Mead, because the former can be served only by two sources, namely, Glen Canyon releases or tributary inflow, while the latter can be served by both of these sources or from water stored in Lake Mead. The uses of water between Lake Mead and Glen Canyon contemplated are the historical uses including pumping from Lake Mead plus an increased annual use of possibly 100,000 acre-feet for consumptive purposes during the filling period, plus evaporation losses from Lake Mead. Paragraph 5 is the statement of principle that there will be an allowance for computed deficiency in Hoover firm energy which is created by virtue of the operations of Glen Canyon. This paragraph also defines deficiency for purposes of computing the amount of allowance. Determination of deficiency depends upon two calculations. The first calculation would be one to determine the so-called Hoover basic firm which is that firm energy that would have been produced in that year at Hoover without Glen Canyon on the river. The Hoover basic firm would be determined by starting with the actual content of Lake Mead in the year 1962 and running a simulated operation study of Hoover as if Glen Canyon were not on the river and using an overall efficiency factor for power operation of 83 percent. The second calculation would be to adjust the energy actually generated at Hoover (which even without Glen Canyon on the river, actual operating practice shows would probably be produced at an efficiency varying from 70 to 78 percent) to an efficiency factor of 83 percent. The difference between these two answers would, for purposes of the allowance, be considered as the deficiency in firm energy. At the present time the operations of the powerplant at Hoover are such as to create relatively low efficiency. This is so because the power allottees are to an extent utilizing the Hoover generators for peaking purposes. We do not believe it appropriate to compensate the allottees for that portion of the use of the Hoover plants which represents a type of operation dictated by their own convenience. |