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Beneficial Consumptive Uses An extensive discussion of consumptive uses is not anempted in this report as that subject has been treated in detail in Reclamation's "Colorado River System Consumptive Uses and Losses Report, 1981-1985." This report has been prepared jointly by the Upper and Lower Colorado Regional Offices and is due to be released in 1988. It presents e,stimates of t he consumptive uses and losses from the Colorado River System for each year from 1981tbrough 1985. The foUowing tahle summarizes annual water use from the system by States, including water use supplied by ground-water overdraft. Upper Basin Uses and Losses The three largest categories of consumptive use in the Upper Colorado River Basin are agricultural uses within the basin, transbasin diversions to adjacent drainages, and evaporation losses from the major reservoirs of the Colorado River System. During water year 1986, the estimated use for municipal and industrial supply and for agriculture in tbe Upper Basin was 2,800,000 acre-feet. Estimated evaporation losses were 610,()(X) acre-feet from mainstem reservoirs. About 670,000 acre-feet was diverted for use in adjacent drainages. Total estimatcd consumptive use amounted to 3,700,000 acre-feet. Storage in the Upper Basin mainstem reservoirs increased by approximately 888,000 acre.feet during water year 1986. Lower Basin Uses and Losses During water year 1986, an estimated 5.3 MAP of water were released from Lake Havasu to meet the requirements for water deliveries at Imperial Oam, as wen as those of the Colorado River Indian Reservation near Parker, Arizona, the Palo Verde Irrigation Oistrict near Blythe, California, other miscellaneous users along the river, and transit losses between Parker Dam and Imperial Dam. The major water diversion above Parker Dam was by MWD. MWD pumped approximately 1,294,000 acre-feet from Lake Havasu during water year 1986. Releases of approximately 6.6 MAP were made from Lake Mohave during water year 1986 to meet minimum downstream needs in the United States at Parker Dam; to supply diversion requirements of MWD, miscellaneous contractors, "1'd other users; to offset evaporation and other transit losses between Oavis and Parker Oams; and to maintain the scheduled levels of Lake Havasu. During water year 1986, releases of approximately 6.6 MAF were made from Lake Mead at Hoover Dam to regulate the levels of Lake Mohave, to provide for the small users from that reservoir, and to provide for releases at Davis Dam. In addition, 175,000 acre-feet were diverted from Lake Mead for use by the Lake Mead National Recreation Area, Boulder City; Basic Management, Inc.; and contractors of the Colorado River Commission of Nevada. Total releases and diversions from Lake Mead during water year 1986 were an estimated 17,388,000 acre. feet. For water year 1987, a total release of 12.2 MAF from Lake Havasu has been projected, including consumptive use requirements in the United States below Parker Dam, transit losses and regulation in the river between Parker Dam and the Mexican Border, flood control requirements, and treaty deliveries to Mexico. During water year 1987, MWD is expected to divert 1,269,000 acre-feet by pumping from Lake Havasu. Consumptive uses by small users, river losses or gains, and reservoir losses between Oavis Oam and Parker Oam are projected to be a net loss of 120,000 acre.feet. There are no major users between Hoover Dam and Oavis Oam. Ouring water year 1987 the net diversions from Lake Mead are projected at 141,000 acre-feet. Evaporation from Lake Mead is projected to be about 980,000 acre-feet and nct gain between Glen Canyon Oam and Lake Mead is expected to be about 886,000 acre- feet. 23