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<br />J: '306 <br />J_ , <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) <br />