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<br />10
<br />
<br />DEPLETION OF SURFACE WATER SuPPLIES
<br />
<br />Summary oj present depletions
<br />The total of all depletions in Oolorado of the waters originating in
<br />the drainage basin of Oolorado River is now practically 1,450,000
<br />acre-feet per year, made up of the following: .
<br />
<br />~V' <
<br />
<br />Depletions with existing facilities]
<br />[Acre~feet ,per year]
<br />
<br />Geographic division
<br />
<br />Trans-
<br />mountain
<br />diversions
<br />
<br />Total at
<br />sites of
<br />use
<br />
<br />Irrigation
<br />
<br />Other
<br />depletions
<br />
<br />; Green River Basln____~__________~~_h_______u
<br />"Colorado River, main stemu____~___n~____nn
<br />. Gunntson River Basin__"-______~_______________ .
<br />; Dolores River Basin and lower San Juan River
<br />trlbutarJes_ _ _ ~ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ __
<br />San Juan River Basin above SbJprock_____n_h
<br />
<br />Totals at sites of US6_____n_n_n_nn__n
<br />
<br />1,000
<br />19,800
<br />5,000
<br />
<br />99, 100
<br />766,200
<br />353, 800
<br />120, 500
<br />109, 500
<br />
<br />98, 100
<br />371, 400
<br />348, 200
<br />
<br />116, 600
<br />100,700
<br />
<br />1, 035, 000
<br />
<br />375,000
<br />600
<br />
<br />3,900
<br />7,200
<br />36, 900
<br />
<br />1,600
<br />377, 200
<br />
<br />1, 449, 100
<br />
<br />If the provisions of section Cd) of Article III of the Oolorado River
<br />Compact can be satisfied with aggregate depletions in the Upper Basin
<br />as great as 7,500,000 acre-feet per year, then at least 2,250,000 acre-
<br />feet of water now remain to satisfy potential developments in 0010-
<br />rado. On the 'other hand, if depletions in the upper basin must be
<br />held down to insure the delivery of 75 million acre-feet at Lee Ferry
<br />in each continuous 10-year period, then the actual surplus under exist-
<br />ing conditions may not exceed 1,650,000 acre-feet per year.
<br />
<br />Oommitted supplies
<br />. Some-of the present surplus of Oolorado River water will be needed
<br />for expansion of existing projects and to supply Federal projects which
<br />are now authorized. It is the view of many that this amount of water
<br />should be included among present depletions; others believe that these
<br />additional uses should be treated as potential depletions for which
<br />some water should be earmarked. In order that there may be nQ
<br />confusion, the estimates of the Engineering Research Oommittee as
<br />to these are set forth below.
<br />No increase in depletion by existing projects is contemplated in the
<br />Green River Basin. An increase of only 400 acre-feet is deemed
<br />probable in the San Juan Basin, this through existing facilities used
<br />for transmountain diversions. Other transmountain diversions, al-
<br />most entirely from the headwaters of Oolorado River, could be in"
<br />cpeased abou! 1pO,000 acre-f~et per year under present rights. Expan-
<br />SlOn of the IrrIgated area III the Grand Valley and Uncompahgre
<br />Federal projects would consume 69,000 acre-feet per year.
<br />In addition, two projects have been authorized by the Oongress of
<br />the United States for which appropriations have yet to be made. It
<br />is'estimated by the Bureau of Reclamation that these would deplete
<br />the flow of Oolorado River by 28,300 acre-feet per year.
<br />Such expansion of use by existing projects and new uses by author-
<br />ized Federal projects would aggregate almost 200,000 acre-feet per
<br />year. Hence, the quantity of water available to Oolorado to satisfy
<br />otp,erpotential demands can be little niore than about 2,050,000 acre-
<br />feet per year, and because of the limitations of the compacts may not
<br />exceed 1,450,000 acre-feet per year.
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