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30 OOr,ORADORIVER S'l'ORAGE PROJEO'l' increasing. Ther~ is, of course\ a relationship between the extent of upper basin uses ltnd the availability of water to the lower basin. The studies perforjned by the engineering groups assumed releases at Hoover of 7.5 million acre.feet by the upper basin group, as well as assumptions by bo~h groups of 8.5 million acre.feet in 1962, increasing to 9.3 million acr~.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 tile 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 l?er year which is permissible under the treaty on an "if available" basIs. Paragraph 4 is ~imilar 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 Oan. yon Dam and Lake Mead and to the use of water directly out of Lake Mead. It is necessary to separate the uses between Glen Oanyon and the upper end of Lake Mead from those which are or might be made directly outi of Lake Mead, because the former can be served ouly by two sou~ces, namely, Glen Oanyon releases or tributary infl:ow, while the hitter can be served by both of these sources or from water stored in L~ke Mead. The uses of water between Lake Mead and Glen Oanyorl. 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 coniputed deficiency in Hoover firm energy which is created by virtue9f the operations of Glen Oanyon. This paragraph also defines deficiency for purposes of computing the amount of allowance. Deterjnination of deficiency depends upon two calcula. tions. The first c~lculation 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 Oanyon on the river. The Hoover basiq 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 Oanyon were not on the river and using an overall efficiency factor for power operation of 83 per. cent. The second: calculation would be to adjust the energy actually generated at Hoover (which even without Glen Oanyon 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 pur- poses of the allowlince, be considered as the deficiency in firm energy. ,. At the present time the operations of the powerplant at Hoover are such as to create relfLtively 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 fLllottees for tl).at portion of the use of the Hoover plants which represents a type lof operation dictated by their own convenience.