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

area extends from th~ Continental Divide in
New Mexico to the riyer's mouth near Yuma,
Ariz. Elevations in the basin range from
nearly 12,000 feet in the eastern mountains
to about 150 feet at the mouth. The selected
outflow point for the pasin is at Painted Rock
Dam, a flood control ~tructure located about 20
miles west of Gila Bepd, Ariz. The drainage
area above Painted Rock Dam is about
50,9qO square miles,iof which 5,600 square
miles are in New Mexico and 1,100 square
\
mires in Mexico. The dam was constructed to
protect agricultural a~d urban developments
downstream. Major conservation storage reser-
voirs in the basin incl~de the San Carlos Re-
servoir on the Gila Riv~r; Lake Pleasant on
the Agua Fria River; a8d the six reservoirs of
the Salt River Project.:Total usabl!' capacity
of these reservoirs is a~out 3,180,000 acre-
feet. '
Nearly 75 percent of; the population of the
Lower Colorado River s~stem lives in the Gi la
Rtiver Basin; most of tMese reside in the
metropolitan Phoenix a~d Tucson areas. In-
dustry and recreation p'laya large part in the
economy. ;
About two-thirds of tliie agricultural de-
velopment in the Lower!colorado River system
is located in the Gila River Basin. This de-
velopment is concentrated in the central
area of Maricopa, PinaJ) and Pima Counties
and is supported to a large degree by a long-
term overdraft of the grQund water resources.
Nearly all of the surface (water resources in the
basin have been develop;ed for decades. Except
for the infrequent majorl flood event, such as
occurred in 1973, inflows to the Colorado
River mainstream are ne~ligible. Releases
through Painted Rock D~m in water year
1973 totaled 412.700 a'cre-feet although only
slightly more than 100,OPO acre-feet reached
the Colorado River. Construction of the Central
Arizona Project is in progress. This project,
which would divert Color~do River water at
Lake Havasu to central Arizona, is intended
to reduce ground-water pLmpage and par-
tially arrest the large annual increases in the
depths to ground water. '
Remaining area in Arizonal Nevada, and Utah:
Outside of the Colorado R'iver mainstream

and flood plain and the selected tributaries,
development for the most part is limited by
the availability of water and the rugged ter-
rain. In the Boulder City-las Vegas Valley area
there has been a significant increase in the
municipal and industrial demand for water.
Construction wh ich would complete the
Southern Nevada Water Project is scheduled
to begin in 1977. Completion of the project
would allow Nevada to essentially use its
complete entitlement from the Colorado River.
Most of the irrigated lands in this area are lo-
cated in the lower reach of the Virgin River and
Las Vegas Valley in Nevada, on Kanab Creek
in Arizona and Utah, and the lower portions
of the Gila and Bill Williams Rivers in
Arizona. North Las Vegas, las Vegas, Hen-
derson, and Boulder City in Nevada, and
Kingman and Williams in Arizona are the lead-
ing cities.

Terminology

The Colorado River is not only one of the
most highly controlled rivers in the world, but
is also one of the most institutionally encom-
passed. A multitude of legal documents, known
COllectively as the "Law of the River," affect
and sometimes dictate its management and op-
eration. Major documents include:
Colorado River Compact-1922
Boulder Canyon Project Act-1928
California limitation Act-1929
California Seven Party Agreement-1931
Mexican Water Treaty-1944
Upper Colorado River Compact-1948
Colorado River Storage Project Act-1956
United States Supreme Court Decree in
Arizona v. California-1964
Colorado River Basin Project Act-1968
Minute 242 of the International Boundary
and Water Commission, United States
and Mexico-1973
Colorado River Basin Salinity Control
Act-1974
The Colorado River system is defined in the
Colorado River Compact of 1922 as ". . .
that portion of the Colorado River and its
tributaries within the United States," whereas

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