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<br />Beneficial Consumptive Uses
<br />
<br />An extensive discussion of consumptive uses is treated in
<br />detail in Reclamation's "Colorado River System
<br />Consumptive Uses and Losses Report, 1981-1985." This
<br />report is prepared jointly by the Upper and Lower Colorado
<br />Regional Offices. The report presents estimates of the
<br />consumptive uses and losses from the Colorado River System
<br />for each year from 1981 through 1985. The table on the
<br />following page was created using the data from the
<br />Consumptive Uses and Losses Report (June 1991). The table
<br />summarizes annual water use from the system by States,
<br />including water use supplied by ground-water overdraft.
<br />Work is now taking place to compile the 1986-1990 report.
<br />For the 1986-1990 report new techniques will be utilized to
<br />compute consumptive uses and losses. The neW report will
<br />use Geographic Information Systems, Remote Sensing and
<br />Image Processing to determine irrigated acres, crop types and
<br />to compute the consumptive usesofthese crops. It is expected
<br />that the 1989-1990 report will be completed in 1994.
<br />
<br />Upper Basin Uses and Losses
<br />
<br />The three largest categories of consumptive use and losses in
<br />the Upper Colorado River Basin are agricultural uses within
<br />the basin, transhasin diversions to adjacent drainages, and
<br />evaporation losses from the major reservoirs. Estimated
<br />evaporation losses were about 592,000 acre-feet from Upper
<br />Basin reservoirs in water year 1992. In water year 1991,
<br />746,244 acre-feet were diverted for use in adjacent drainages.
<br />The total for transbasin diversions in water year 1992 has not
<br />yet been tabulated but the figure is expected to be similar to
<br />the 1991 total.
<br />
<br />Lower Basin Uses and Losses in the United Slates
<br />
<br />During water year 1992, an estimated 6.0 million acre-feet of
<br />water were released from Lake Havasu (Parker Dam) to meet
<br />the requirements for water deliveries at Imperial Dam, as well
<br />as those of the Colorado River Indian Reservation near
<br />Parker, Arizona, the Palo Verde Irrigation District near
<br />Blythe, California, other miscellaneous users along the river,
<br />and transit losses between Parker Dam and Imperial Dam.
<br />
<br />The major water diversions above Parker Dam were by The
<br />Metropolitan Water District (MWD) of Southern California
<br />and the Central Arizona Project (CAP). MWD pumped
<br />approximately 1,187,000 acre-feet from Lake Havasu during
<br />
<br />water year 1992, and approximately 522,000 acre-feet were
<br />pumped for the CAP.
<br />
<br />Releases of approximately 7.5 million acre-feet were made
<br />from Lake Mohave during water year 1992, to provide for
<br />releases to meet minimum downstream needs in the United
<br />States at Parker Dam; to supply diversion requirements of
<br />MWD and CAP, miscellaneous contractors, and other users;
<br />to offset evaporation and other transit losses between Davis
<br />and Parker dams; and to maintain the scheduled levels of Lake
<br />Havasu.
<br />
<br />During water year 1992, releases of approximately 8.0 million
<br />acre-feet were made from Lake Mead at Hoover Dam. These
<br />releases regulate the levels of Lake Mohave, provide for the
<br />small users on that reservoir, and provide for releases at Davis
<br />Dam to meet needs in the United States. In addition, 280,000
<br />acre-feet were diverted from Lake Mead for use by the Lake
<br />~fead National Recreation Area; Boulder City; Basic
<br />Management, Inc.; and contractors of the Colorado River
<br />Commission of Nevada. Of the diversions from Lake Mead,
<br />approximately 160,000 acre-feet were consumptively used and
<br />the remainder returned to Lake Mead. Total releases and
<br />diversions from Lakt: Mead during water year 1992 were
<br />8,290,000 acre-feet.
<br />
<br />For water year 1993, a total release of 6.7 million acre-feet
<br />from Lake Havasu is projected, including consumptive use
<br />requirements in the United States below Parker Dam, transit
<br />losses and regulation in the river between Parker Dam and the
<br />Mexican Border, and treaty deliveries to Mexico.
<br />
<br />It is expected that MWD will divert 1,300,000 acre-feet by
<br />pumping from Lake Havasu during water year 1993. Similarly,
<br />the CAP is expected to pump approximately 750,000
<br />acre.feet. Consumptive uses by small users, river losses or
<br />gains, and reservoir losses between Davis Dam and Parker
<br />Dam are projected to be a net loss of 35,000 acre-feet.
<br />
<br />There are no major users between Hoover Dam and Davis
<br />Dam. Duringwater year 1993, diversions from Lake Mead are
<br />projected at 310,000 acre-feet. Evaporation from Lake Mead
<br />is projected to be about 800,000 acre-feet and net gain
<br />between Glen Canyon Dam and Lake Mead is expected to be
<br />about 800,000 acre-feet.
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