WSP02976

• File Number: 8271.300
• Description: Colorado River Basin Salinity Control Program - General Information and Publications-Reports
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 12/1/1979
• Title: An Economic Evaluation of the Salinity Impacts From Energy Development - The Case of the Upper Colorado River Basin
• Water Supply Pro - Doc Type: Report/Study

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III. WATER RESOURGES Of THE
UPPER COLORADO BASIN

Develop~ent of the abundant enervy
resources of the Upper Colorado River Basin
is ,!::wing to require substantial amounts of
water. The necessary water will largely have
to be obtained from previous users, and
the transfer will have to be accomplished in
a manner that does not appreciably worsen
salinity for Lower Basin and Mexican users.
In order to determine how the reallocation
can best be achieved within this constraint,
information is needed on water availability,
water quality, present and planned water use,
developmental plans, and institutional
situations affecting water resources and
water quality management in the basin.

.

The 1440-mile long Colorado River drains
portions of seven states before flowing into
Mexico. It produces less water per unit area
(60 acre feet annually per square mile) than
any other drainage in the country. One
reason is that high mountain watersheds in a
relatively small percentage of 'the total
Upper Basin provide almost the entire source
for the water needed to support irrigated ag-
riculture, municipal water supply, iDdustry,
mining, wildlife, and recreation.

The Colorado River Basin is divided for
interstate water allocation purposes into an
Upper and Lower Basin, the dividing point
being Lee Ferry, Ar izona, below Glen Canyon
Dam. The Upper Basin states include Wyoming,
Colorado, Utah, and New Mexico (Figure 3).
The laws through which the limited amounts of
available water are allocated among the many
competing uses in this arid climate encompass
a multitude of complex legal and institu-
tional arrangements which are interstate,
interregional, and international in nature.

Water Resources

When unaffected by the activities of man,
surface runoff is referred to as "natural" or
"virgin" flow. Except in the headwater
reaches, few streams in the Upper Colorado
River Basin now carry their natural flow.
Diversions, consumptive use, out-of-basin
exports, and regulations by dams and reser-
voirs have reduced streamflows throughout the
region. Consequently, the average annual
virgin flow of the river can only be esti-
mated by reconstruction from gaged flows and
estimates of consumptive uses in the basin.
The estimates (Upper Colorado River Commis-

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Figure 3.

Water
Upper

resources subareas
Colorado River

for the
Basin.

sion 1973) of average annual virgin (low at
Lee Ferry, Ar lzona, (Figure 4), show larr;e
variations from year to year. The average
annual flows for various periods of record
are shown in Figure 5. Extremes ranged from
a high of 21.894 million acre-feet in 1917 to
a low of 'f.396 million acre-feet in 1934.

Analysis of the water allocation alter-
natives and their salinity impacts requires a
combination of economic, water resources, and
institutional data, all of which must be
brought to a set of common geographical

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