8013

• UCREFRP Catalog Number: 8013
• Author: Pontius, D. and I. SWCA.
• Title: Colorado River Basin Study.
• USFW Year: 1997.
• USFW - Doc Type: Tucson, Arizona.
• Copyright Material: NO

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Background Information

(Table 3). California diverts and uses well over its 4.4 maf apportionment,
Nevada is approaching its 300,000 af apportionment, and Arizona is in the
process of diverting its entire 2.8 maf apportionment. The Upper Basin,
which has been slower to develop, is using approximately 60 percent of its
entitlement (Table 4) and projections vary as to when full development will
occur. In 1996, Lower Basin water use is estimated to be 8.00 maf, compared
to 3.79 mafin the Upper Basin.4

Table 3.-Annual water use (1/000 aft in the lower Basin, 1990-1996
Year
Apportion-
State ment 1990 1991 1992 1993 1994 1995 1996
Arizona 2/800 2/260 1/864 1/906 2/246 2/152 2/221 2/704
California 4/400 5/220 5/006 4/546 4,835 5,234 4,925 5,316
Nevada 300 178 180 178 204 228 217 249
Un- (233) (214 ) (202) (221) (254) (283) (266)
measured
returns
Total 7,500 7,425 6,836 6,428 7,064 7,360 7,081 8,003
1 Arizona v. California (1963).
2 Preliminary estimates (Source: Harkins, 1997).

Approximately 80 percent of the river's supply is used for agriculture. The
largest user of agricultural water is the Imperial Irrigation District (lID) in
southern California, which alone accounts for approximately 2.87 maf
annually (1964-96 average), or almost 20 percent of the river's average
annual flow. Other major agricultural users include the Palo Verde
Irrigation District and the Coachella Valley Water District, which are also in
southern California, the Central Arizona Project, the Central Utah Project
and various other water districts in the Upper Basin. Municipal and
Industrial (M&I) water from the Colorado River water is provided by Denver
Water, the Central Utah Water Conservancy District (CUWCD), the
Metropolitan Water District of Southern California (MWD), the San Diego

4 Harkins, 1997.

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