WSP03306

• File Number: 8281.300
• Description: Colorado River Studies and Investigations - Colorado River Consumptive Uses and Losses Report
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1984
• Title: Colorado River System Consumptive Uses and Losses Report 1976 - 1980
• Water Supply Pro - Doc Type: Report/Study

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Beneficial Consumptive Uses and Losses

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.... A summary table of the Colorado
W River system total annual water uses,
r-:l 1976-l980, by States and basins is
shown on page vi. Tables C-2 through
C-6 show on a yearly basis the same
information broken down by State,
basin, and type of use. Water use
within the sel'ected reporting areas is
discussed below.

Upper Colorado River Tributaries

Summaries of estimated annual
consumptive uses and losses in the
Upper Colorado River Basin for each of
the reporting years, broken down by
State, reporting area, and type of use
are shown in tables UC-2 through UC-6.
Est imated main. stem reservoir evapora-
tion is shown in table UC-1.
Upper Basin consumptive use in-
creased from 2.9 million acre-feet
in 1976 to about 3.3 million acre-feet
at the end of the reporting period,
largely due to water use increases in
irrigated acre'age, thermal electric
power generat'ion, and transbasin
exports.
Agricultura~ uses accounted' for
about 65 perceht of the total Upper
Basin consumptive uses and losses.
Irrigated acreage increased from
l,430,000 acres in 1976 to 1,480,000
'acres in 1980, largely due to the
establishment of the Navajo Indian
Irrigation Project in New Mexico and an
increase in the estimate of the irri-
gated pasture in Wyoming. Changes in
climatic conditions produced additional
variation in consumptive use.
Water use for'therma1 electric power
generation doubled during the reporting
period as it did during the 1971-1975
period. Increases in production at
four recently constructed plants,
San Juan, Navaj 0, Jim Bridger, and
Huntington, and the additional con-
struction of the Hunter and craig
plants accounted for the increase.

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Transbasin exports, the second
largest Upper Basin use, showed great
year-by-year variation during the
reporting period. Exports were reduced
during 1977 due to the Basinwide
drought conditions, increased to a
record 850,000 acre-feet in 1978, and
reduced in 1979 and 1980 apparently due
to an abundant water supply on the
eastern slope of the Rocky Mountains.
The 1977 drought conditions deserve
some mention in this report due to the
great impact on irrigated agriculture.
A very poor spring runoff resulted in
a decrease in the acreage of planted
crops. Lands which were supplied
by reservoirs having sufficient carry-
over storage received a fairly con-
sistent water supply during the irriga-
tion season. Lands Which did not have
sufficient supply had production yields
20 to 40 percent less than in normal
years. The estimated 1977 water use
for irrigation was 30 percent less than
other years, a difference of about
600,000 acre-feet.

Lower Colorado River Mainstream

Table LC-l shows mainstream reser-
voir evaporation and channel losses
and table LC-3 shows water uses along
the lower Colorado River mainstream and
flood plain including water passing to
Mexico. Water passing to Mexico is
made up of deliveries in satisfaction
of the Treaty, deliveries made pursuant
to Minute No. 242, Gila River flood
releases, regulatory waste and antici-
patory flood control releases from the
mainstream. Table LC-2 summarizes the
total water use in the Lower Basin
excluding the mainstream evaporation
and channel losses. Mainstream reser-
voirs gained about 3.3 million ,acre-
feet of surface stor~ge during the
5-year reporting period. Water sup-
plies necessary to meet the mainstream
water use came principally from the

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