<br />J: '306
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<br />17. DISCUSSION OF UJWER BASIN SUMMARY
<br />
<br />Combined
<br />IDss : lee Ferry to Laguna IBm
<br />Colorado River at Laguna Dam
<br />
<br />Vir~in Flows
<br />1 ,271,000
<br />338,000
<br />310,000
<br />16,919,000
<br />468,000
<br />16,451,000
<br />
<br />.
<br />
<br />Colorado River at Lee Ferry
<br />Little Colorado
<br />Virgin
<br />
<br />Aeeuming an Upper Basin depletion of 7,500,000 acre feet, the flow at
<br />Laguna, Dam, with no depletions below Lee Ferry, would have amounted to
<br />8,951,000 acre feet. Adding to this the allowance for a "decrease in channel
<br />losses of 380,000 acre feet," the figure of 9,331,000 acre feet is derived.
<br />In other words the assumption is made, when calculatiq;! available water supplies,
<br />that 380,000 of the 468,000 acre feet of virgin condition channel loss will
<br />have been eliminated, and but 88,000 acre feet thereof will remain. This
<br />indicates that, having charged reservoir evaporation losses to the depletion
<br />account, such depletioIlB include natural losses which probably are not a part
<br />of the beneficial consumptive use quantities specified in the Compact. Similar
<br />treatment in the Upper Basin would segregate the total depletions set forth in
<br />the Report, largely to beneficial consumptive use, but in part to natural
<br />causes for which the States of the Upper Divison are not responsible.
<br />
<br />In any event the 9,331,000 acre feet of calculated water supply cOIlBists
<br />of 8,771,000 acre feet of virgin flow at Lee Ferry (after deducting 7,500,000
<br />acre feet for assumed Upper Basin depletions), plus virgin flows of 338,000
<br />acre feet and 310,000 acre feet in the Little Colorado and Virgin divisions,
<br />minus 88,000 acre feet (the remaining loss Lee Ferry to Laguna Dam in the
<br />Boulder division).
<br />
<br />As compared with that water supply, the Report points out that present,
<br />future, and potential depletions in the Little Colorado, Virgin and Boulder
<br />divisiora(whioh include reservoir losses of 870,000 acre feet, but are exclu-
<br />sive of depletions in the Gila River, and of any allocation to Mexico by
<br />international agreement), total 9,922,600 acre feet, Hence, the Report
<br />concludes: "It is therefore evident that the projects discussed will need to
<br />be modified to conform to the available water supply."
<br />
<br />,
<br />
<br />In this Lower Basin Summary, the Report might properly point out that:
<br />The exclusion of the Gila River from this water supply-depletion
<br />comparison is not to be construsd as an interpretation of the Colorado River
<br />Compact;
<br />The present (actual) depletions in the three divisions involved in this
<br />calculation total 3,347,100 acre feet annually;
<br />To provide for the future irrigation of an estimated 579,000 acres of
<br />irrigable land attaching to existing enterprises in the Boulder division,
<br />an allaWnce in the nature of a reservation in the amount of 4,265,200 acre
<br />feet, measured as depletions, has been made;
<br />If and when the said quantity is diverted and used, the aggregate
<br />depletions in the three division will amount to 7,612,300 acre feet annually;
<br />
<br />"
<br />
<br />(26)
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