WSP11823

• File Number: 8281.400
• Description: Colorado River Studies and Investigations -- Colorado River Depletion Projections
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 3/25/1955
• Title: Report on Depletion of Surface Water Supplied of Colorado West of Continental Divide
• Water Supply Pro - Doc Type: Report/Study

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DEPLETION OF WATER SUPPLIES ALLOCATED TO STATE OF
COLORADO BY COLORADO RIVER COMPACTS

. Expa:nsion of agriculture, development of industry, and growth of
the cities of Colorado depend upon the most effective use of the avail-
able supplies of water. Substantially complete use has already been
made of those portions of the total flow of Platte River, Arkansas
River,aJJ,d Rio Grande to which Colorado is entitled. The contrary
is true, however, in the case of Colorado River l>nd its tributl>ries.
Hence, the bl>sic question: Is the amount of water available to Colo-
rado from this last source more than will be needed to satisfy all reason-
able beneticial uses within the drainage basin of Colorado River?
It,sholild be obvious to everyone familiar with physical cOnditions
that all of the woter to which Colorado is entitled under the provisions
of the Cqlorado River compact and the upper Colorado River Basin
Compact could be consumed in the irrigation of lands on the western
slope if nQ limit were to be placed on costs of construction and opera-
tion of irrigation works. It is equally true, although less apparent,
that all of the present surplus of Colorado River water could be con-
sumed' in' industrial processes if again there were no economic
limitations.
It follows, therefore, that existing conflicts between interests in
different parts of Colorado and potential conflicts between agricultural
and .industrial users of water on the western slope cannot be reconciled
linless reaslmable limits are placed upon the cost of providing water
to satisfy each potential demand upon the available supply from Colo~
rado River;and its tributaries.

WATER SUPPLY

.... The surp\us now available for agricultural, industrial, and other pur-
posesis materially less than might be presumed from observation of
the flow of the rivers on the western slope during the period, of snow-
melt each year, Under the provisions of the Colorado River Compact
some of the~e floodwaters must be passed down for use in the lower
basin, and by the Compact of 1948 Colorado agreed to limit its use of
water to a little more than one-half of the total allocated to the upper
basin. .
. The annu~l discharge of Colorado River and each of its tributaries
varies through wide limits and there has been a tendency for wet years
to occur in groups, followed by extended periods in which the runoff
ili generally l~ss than the long-time average. . For example, the quan-
tity of wate}\ passing Lee Ferry in northern Arizona, the point of
delivery to the lower basin, averaged 15.9 million acre-feet per year
for the 17 ye~s from October 1,1913, to September 30,1930, as com-
pared to only, 11.7 million acre-feet per year for the next 23 years;
also, thehistoi'ical runoff at Lee Ferry ranged from a maximum of 18.0
million acre-feet to a minimum of 4.4 million acre-feet within this last
period in whicl,1 the average was 11.7 millionacre-feet per year.

60526--55----2 1

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