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<br />4. Upper Basin Supplies and ():lpletions (Cont'd)l
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<br />and the'virgin flow was estimated at 12,210_000 acre feet alIDually
<br />during J931-1940. The difference, or 2,04,.000 acre feet, repre-
<br />sents the estimated upstream depletions in the average year of the
<br />1931-1940 period, whereas the figure of 2,440,000 acre feet ap-
<br />pearing in the Report represents present depletions after certain
<br />~ projects now authorized came into operation.
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<br />NOTE (5) I If, as stated in the Report. the Compact allocated 7,500,000 acre
<br />feet annually to the Upper Basin for beneficial consumptive use,
<br />total depletions would become 7,500.000 acre feet plus natural con-
<br />veyance losses to Itle l<'erry. But the Report contemplates that,
<br />when the channel has been converted to a series of reservoirs, the
<br />evaporation losses from the reservoirs becomes chargeable against
<br />the allocated 7.500,000 acre feet. Actually, the present channel
<br />losses should be determined, and the reservoir losses chargeable
<br />against the Upper Basin should be limited to the increase caused
<br />by reservoir construction and operation.
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<br />5. Lower Basin Supplies and Depletionsl
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<br />When present and potential depletions in the Upper Basin reach
<br />7,500.000 acre feet annually. the Report estimates the flow at Laguna Dam
<br />at 9.331,000 acre feet. This figure is derived by subtracting 7.500.000
<br />from 16,451,000 (the virgin flow at Laguna Dam), and adding 380,000 acre
<br />feet, for estimated reductions in channel losses.
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<br />Present depletions in the Lo~r Basin are estimated at 4,497,100
<br />acre feet pel' year, - a figure formerly mentioned at 4,500,000 acre feet as
<br />including an allowance for depletions to result from 579,000 acres of land
<br />yet non-irrigated. Total present depletions inc lude :,299,900 acre feet on
<br />tributaries (Gila River 1,150,000 and others 149,900), and 3,197,200 on the
<br />ColoradO River. This main river total includes 713.000 acre feet of reser-
<br />voir loss, and 2,484,200 acre feet of irrigation depletions, distributed by
<br />statesl 20,000 in Nevada; 2,193,000 in California; and 271.200 in Arizona.
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<br />Estimated future increased depletions in the Lower Basin, assuming
<br />the construction of all projects described in the Report, total 6,595,500
<br />acre feet, of which 152,300 acre feet on tributaries, and 6,443.200 on the
<br />Colorado River. The main river depletions include 157,000 acre feet of in-
<br />oreased reservoir loss. and 6,286,200 acre feet of increased irrigation c:j.e-
<br />pletions. distributed by StateSI 8,000 in New Mexico; 198,000 in Nevada;
<br />3,456.500 in California; and 2.623,700 in Arizona.
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<br />Present and potential depletions (of desoribed projects) in,the
<br />Lower Basin are estimated at 11,092,600 acre feet. of which 870,000 are
<br />charged to main stream reservoir losses, and 10,222,600 to irrigation deple-
<br />tions, distributed by Statesl 101,500 in Utah; 36,100 in New Mexico; 257,200
<br />in Nevada; 5,649,500 in California; and 4,178,300 in Arizona. The irriga-
<br />tion depletions occur to the extent of 1,452,200 aore feet on tributaries,
<br />prinoipally Gila River (1,170,000 acre feet), and 8.770.400 acre feet on the
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