WMOD00569

• Title: Snowpack, Cloud Seeding and the Colorado River
• Date: 1/1/1974
• Weather Modification - Doc Type: Report

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ALLUl:A IIUN t:lY
"LAW OF THE RIVER

ECONOMIC EFFECTS

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EXISTING .USES

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MEXICO
UPPER BASIN
LOWER BASIN

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LOSSES

AVERAGE VIRGIN
FLOW AT LEE FERRY.
ARIZONA

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Colorado River water supply

12

Fig.

created water shortages. The slow rate of economic develop-
ment that would be expected in the Upper Basin would not
create water shortages for a great many years (Figure 12).

WOSA Water-A Question of Ownership

The allocation of the water supply of the Colorado River has
been the subject of long and bitter disputes among the states
through which it flows. The history of agreements, legislation,

49

SNOWPACK, CLOUD-SEEDING, AND THE COLORADO RIVER

A reasonable estimate of the existing average Colorado
River water supply is 13.8 million acre-feet per year. This is the
amount that would flow out of the Upper Basin into the Lower
Basin if man took nothing out. Almost no water flows out of the
Colorado River into the Gulf of California. Evaporation (and
other losses) and man's uses account for about 12 million acre-
feet per year. Of this amount around 3 million acre-feet dis-
appears from the Upper Basin. The difference between the
natural supply (13.8 million acre-feet) and the depletion (12
million acre-feet) of around 1.8 million acre-feet per year is
filling Colorado River Basin Reservoirs. The usable capacity of
the major reservoirs-some 60 million acre-feet-is a little over
half-filled.
The allocation of the Colorado River water supply implied
by the Compact of 1922 and the Mexican Treaty would seem to
call for a minimum average annual stream flow of 17.5 million
acre-feet. However, large reservoirs are necessary to stabilize
the flow and regulate the water diversions in order that these
allocations can be used. Large evaporation losses from the sur-
faces of these reservoirs can be expected in addition to other
natural losses. Accordingly, at least 19 million acre-feet is neces-
sary each year to satisfy this allocation.
If all authorized projects were constructed, California
would have to give up 0.7 million acre-feet per year now being
used, and the Colorado River water supply would have to be
augmented to satisfy the Mexican Water Treaty. California is
already augmenting its south coastal supply from other sources.
However, if each state is to receive its full entitlement, the water
supply will have to be increased. To build the authorized proj-
ects, Congress would have to appropriate large sums of money.
Upper Basin water use would have to increase sharply before all
the states of the basin would need their full entitlement. The
only development that could bring this about is extensive ex-
ploitation of Upper Basin coal and oil shale mineral resources.
WOSA would be needed in a very few years if Congress ap-
propriated the money for the authorized projects and thereby

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48

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