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<br />Beneficial Consumptive Uses
<br />
<br />An extensive discussion of consumptive uses is treated in
<br />detail in Reclamation's draft "Colorado River System
<br />Consumptive Uses and Losses Reporl, 1981-1985." That
<br />report is prepared jointly by the Upper and Lower
<br />Colorado Regional Offices. The report was scheduled for
<br />release in 1988, but has not yet been published due tOlechnical
<br />review questions. The report is currently receiving final
<br />review and will likely be published in the fIrst part of 1991.
<br />The report presents estimates of the consumpti're uses and
<br />losses from the Colorado River System for each year from
<br />1981 through 1985. The table on the following page was
<br />created by the provisional data from the most recent draft
<br />copyoftheConsumpti", U sesand Losses Report (September
<br />1990), which surrunarizes annual water use from the system by
<br />States. including water use supplied by ground-water
<br />ovcrdrafl. The 1986-1990report, is expected to be awilable in
<br />1992.
<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 acc agricultural uses within
<br />the basin, transbasin diversions to adjacent drainages, and
<br />evaporation losses from the major reservoirs of the Colorado
<br />River System. Estimated evaporation losses were about
<br />630,000 acre-feet from mainstem resermirs in water year
<br />1990. In water year 1989,737,500 acre-feel were diverted for
<br />use in adjacent drainages. The total for trans basin diversions
<br />in water year 1990 has not yet been tabulated but the figure is
<br />expected to be similar to the 1989 total.
<br />
<br />Lo"". Basin Uses and Losses in the United States
<br />
<br />During water year 1990, an estimated 5.6 million acre-feet of
<br />water were released from Lake Havasu to meet the
<br />requirements for water deliveries at lmperial Dam, as wen as
<br />those of the Colorado River Indian Reservation near Parker,
<br />Arizona. the Palo Verde Irrigation District near Blythe.
<br />California, other miscellaneous users along the river, and
<br />transit losses between Parker Dam and Imperial Dam.
<br />
<br />The major Vr'3.ter diversions above Parker Dam were by The
<br />Metropolitan Water District (MWD) of Southern California
<br />and the Central Ariwna Project (CAP). MWD pumped
<br />approximately 1,240,000 acre-feet from Lake Havasu during
<br />water year 1990, and approximately 779,0CJ0 acre-feet were
<br />pumped for the CAP.
<br />
<br />Releases of approximately 7.7 million acre-feet were made
<br />from Lake Moha", during water year 1990, to provide for
<br />releases to meet minimum downstream needs in the
<br />United States at Parker Dam; to supply diversion
<br />requirements ofMWD and CAP. miscellaneous contractors,
<br />and other users; to offset evaporation and other transit losses
<br />between Da...;s and Parker dams; and to maintain the
<br />scheduled le",ls of Lake Havasu.
<br />
<br />During water year 1990, releases ofappro.ximately 8.0 million
<br />acre-feet were made from Lake Mead at Hoover Dam to
<br />regulate the le",ls of Lake Moha"" to provide for the small
<br />users that reservoir, and to provide for releases at Davis Dam
<br />to meet needs in the United States. In addition,
<br />267,(X)() acre-feet were diverted from Lake Mead for use by
<br />the Lake Mead National Rccreation Area, Boulder City;
<br />Basic Management, Inc.j and contractors of the Colorado
<br />River Commission of Nevada. Of the diversions from Lake
<br />Mead, approxirnate:ly 150,()(X) acre-feet were consumptively
<br />used and the remainder returned to Lake Mead. Total
<br />releases and diversions from Lake fvlead during water year
<br />1990 were an estimated 9,590,000 acre-feet.
<br />
<br />For water year 1991, 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 Darn, transit
<br />losses and regulation in the river between Parker Dam and the
<br />Mexican Border, and treaty deliveries to Mexico.
<br />
<br />Based on studies made in October 1990, it is expected that
<br />MWD will divert 1,100,000 acre-feet by pumping from
<br />Lake Havasu during water year 1991. Similarly, thc CAP is
<br />expected to pump approximately 1,060,000 acre-feet. These
<br />figures may change as the water year progresses. Consumptive
<br />uses by small users, river losses or gains, and reservoir losses
<br />between Da'\is Dam and Parker Dam are projected to be a
<br />net loss of 66,000 acre-feet.
<br />
<br />There are no major users between Hoover Dam and
<br />Da...;s Dam. During water year 1991, diversions from
<br />Lake Mead are projected at 312,()(X) acre-feet. E\.'3poration
<br />from Lake Mead is projecled to be about 840,000 acre-feet
<br />and net gain between Glen Canyon Dam and Lake Mead is
<br />expected lo be about 950,000 acre-feet.
<br />
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