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Beneficial Consumptive Uses An extensive discussion of consumptive uses is treated in detail in Reclamation's "Colorado River System Consumptive Uses and Losses Report, 1981-1985." That report was prepared jointly by the Upper and Lower Colorado Regional Offices and was scheduled for release in 1988, but has not yet been publisbed due to technical review questions. The report presents estimates of the consumptive uses and losses from, the Colorado River System for each year from 1981 through 1985. The table,lOn the following page was created by the provisional data from that report, which summarizes annual water use from the system by States, including water use supplied by ground-water overdraft. The next report, 1986-1990, is expected to be available in 1992. Upper Basin Uses and Losses The three largest categories of consumptive use and losses in the Upper Colorado River Basin are agricultural uses within the basin, transhasin diversions to adjacent drainages, and evaporation losses from the major reservoirs of the Colorado River System. During water year 1988, the estimated use for municipal, industrial and agriculture supplies in the Upper Basin was about 2.950 MAF. Estimated evaporation losses were about 720,000 acre-feet from mainstem reservoirs. Approximately 680,000 acre-feet was diverted for use in adjacent drainages. Total estimated consumptive use amounted to about 3.85 MAF. Storage in the Upper Basin main stem reservoirs decreased by 870,000 acre-feet during water year 1988. - Lower Basin Uses and Losses During water year 1988, an estimated 5.1 MAF of water were released from Lake Havasu to meet the requirements for water deliveries at Imperial Dam as well as those of the Colorado River Indian Reservation near Parker, Arizona, the Palo Verde Irrigation District near Blythe, California, other miscellaneous users along the river, and transit losses between Parker Dam and Imperial Dam. The major water diversions above Parker Dam were by MWD and the CAP. MWD pumped approximately 1.207 MAF from Lake Havasu during water year 1988 and approximately 490,000 acre-feet were pumped for the CAP. Releases of approximately 6.8 MAF were made from Lake Mobave during water year 1988, to provide for releases to meet minimum downstream needs in the United States at Parker Dam; to supply diversion requirements of MWD and CAP, miscellaneous contractors, and other users; to offset evaporation and other transit losses between Davis and Parker dams; and to maintain the scheduled levels of Lake Havasu. During water year 1988, releases of approximately 6.7 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 to meet needs in the United States. In addition, 199,000 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 1988 were an estimated 9.887 MAF. For water year 1989, a total release of 6.2 MAF from Lake Havasu is 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, and treaty deliveries to Mexico. During water year 1989, MWD is expected to divert 1,334,000 acre-feet by pumping from Lake Havasu. The CAP is expected to pump approximately 741,000 acre-feet. Consumptive uses by small users, river losses or gains, and reservoir losses between Davis Dam and Parker Dam are projected to be a net loss of 46,000 acre-feel. There are no major users between Hoover Dam and Davis Dam. During water year 1989 the net diversions from Lake Mead are projected at 191,000 acre-feel. Evaporation from Lake Mead is projected to be about 940,000 acre-feet and net gain between Glen Canyon Dam and Lake Mead is expected to be about 950,000 acre-feet. 23