WSP07709

• File Number: 8281.300
• Description: Colorado River Studies and Investigations -- Colorado River Consumptive Uses and Losses Reports
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1977
• Title: Colorado River System Consumptive Uses and Losses Report -- 1971-1975
• Water Supply Pro - Doc Type: Report/Study

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mates for local areas. The 1975 population of
the lower Colorado River system is esti-
mated ~t about 2.6 million and increasing at
an annual rate of nearly 5 percent. A large
portion;of the population resides within
Marico~a and Pima Counties in Arizona, and in
Clark C(lunty, Nev. Net water use rates for
domestic, urban, and rural uses in the various
reportin'g areas were derived from available
studies)n the metropolitan areas, State
Water Plan reports, and appropriate appen-
dices oflthe Comprehensive Framework
Study, liower Colorado Region.
Mineral ~esources: Arizona leads the Nation in
the prod~ction of copper, producing more than
half of the supply. Following in copper pro-
duction are Utah, New Mexico, Montana,
and Nevada. Most of the copper production,
however, tin Utah, New Mexico, and Nevada is
produced! outside of the Lower Colorado River
system. l1he net water use for the production
of copped represents about 90 percent of the
total water use for the production of minerals
within th~ Lower Colorado River system. The
net water ,use for copper and other mineral
productio~, composed principally of the by-
products and coproducts of copper production
(gold, silver, molybdenum, lead, zinc) sand
and gravel! lime, coal, stone, pumice, and ce-
ment, waslestimated from available produc-
tion data iind nominal water use rates. A
large part df the information used to estimate
current water uses by the mineral industry
comes from the Bureau of Mines. This informa-
tion includ~s preliminary figures of annual
, gross valueland quantities of mineral produc-
tion by Sta~e. Basic data available from the
Bureau of Mines include published figures
of gross val~e of mineral production in rela-
tion to amolmt of water consumed and is ex-
pressed as ~allons consumed per dollar of pro-
duction. Figures are available for many min-
erai types rr/,ined and produced in Arizona and
Nevada. A cbntinued updating of unit price
for each mi~eral in relation to quantity pro-
duced is maIntained to arrive at current con-
sumptive us~ figures based on current gallons
consumed per dollar of production figures.
Electric Pow~r: The net use of water for the
production ot thermal electric energy from the

tributaries of the lower Colorado River sys-
tem was estimated from diversions to pow-
erplants and from information contained in
State water plan reports.
Fish and Wildlife: The many multipurpose lakes,
stockponds, and impoundments in the
tributaries are used extensively for fishing and
recreation activities, as well as for preser-
vation of wildlife. Water consumption in the
form of evaporation from these facilities has
been included as lake evaporation in this re-
port. There is little information concerning the
remaining water consumption for fish and
wildlife purposes which may occur at fish
hatcheries, marshes, and on croplands ad-
ministered by the United States or various
State Fish and Wildlife Agencies. These re-
maining uses are believed to be relatively
small in the tributary areas and have not been
included in this report.
Recreation: At many of the lakes, reservoirs,
and impoundments, recreation may be one
of the important functions or purposes,
Other minor water uses for recreation pur-
poses have not been inCluded herein.
Exports: The relatively minor exports of tributary
water outside the Lower Colorado River system
are measured by the Geological Surveyor
water-using organizations..Si.milarly, most of
the exports between tributaries or reporting
areas are measured. Water used to transport
coal from the Black Mesa (Arizona) to the
Mohave Steam Plant (Nevada) is estimated
from records of coal burned at the plant.

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Adequacy of Data

The adequacy of data is judged on the
basis for which it is to be used. Methods of
estimating consumptive use are normally es-
tablished by theoretical or indirect ap-
proaches. A formula may be dependent on a
number of variables. The relationship and
achievable accuracy of each variable must be
weighed carefully with the results to justify
any significant upgrading of data with re-
spect to accuracy and adequacy.
To a degree, this report makes use of the
1965 development year estimates of consump-
tive use prepared for the Upper and Lower
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