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<br />-7- <br /> <br />5. Item 5 relates to hold-over reservoir evaporation losses. In <br />your explanation you refer to the March, 1949, report of Region IV, Bureau <br />of Reclamation, entitled "Colorado River Storage Project and Farticipating <br />Projects." This report bears the stamp IIPreliminary Draft of Proposed Report <br />for Review Only Not for Public Release". You state that this report shows <br />that a hold-over reservoir capacity of 48,065,000 must be provided. The <br />figure used is the totaJ. reservoir capacity of the reservoirs included <br />within the report (see table on p. 12). In regard to the necessary hold- <br />over capacity the report says (p.22): <br /> <br />"Consummation of the average annual use of 7,450,000 <br />acre-feet of Upper Colorado River Basin water apportioned <br />the States of the Upper Division by the Upper Colorado <br />River Basin Compact is pO$sible only through long-term <br />river regulation in hold-over reservoirs above Lee Ferry <br />with an aggregate live capacity of approximately 23,000,000." <br /> <br />It should be noted that .of the reservoirs listed on page 12, three <br />do not have any capacity reserve for hold-over storage. None of such raseI'... <br />voirs has been authorized for construction. Until sites and capacities are <br />definitely determined, any figure placed upon reservoir evaporation loss is <br />a guess. Perhaps the best estimate available is that of Region' IV in its ' <br />report of the Colorado Riveritorage Project. On page 50 of that report is <br />a table which gives the regulatory reservoir evaporation loss as 794,000 <br />acre-feet annually under conditions of tull development. <br /> <br />The formula for charging evaporation losses from reservoirs, used <br />to assist in making Lee Ferry deliveries, requires that.charges to each <br />Upper Division State be made "in the proportion which the consumptive USe <br />of water in each state of the Upper Division wring the water year in which <br />the charge is made bears to the totaJ. consumptive use of water in all States <br />of the Upper Division during the same water year." Thus, the percentage <br />chargeable to each State is a variable factor. It cannot be correctly <br />assumed that such percentage will be constant or will be (as you assumed) <br />the same as the percentage of use apportioned to each State. Further, it <br />should be pointed out that these reservoir evaporation losses include those <br />from the proposed Glen Canyon. storage and it has been maintained by Colorado, <br />as well as by other Upper Basin states, that the Lower Basin should be charged <br />with a portion of these losses. <br /> <br />6. In this item you fix the ~;festern Colorado present use at 1,129,000 <br />acre-feet annually. The figure is taken from the Bureau of Reclamation Blue <br />Book, p. 186, Table CUI. The Engineering Advisory Conunittee to the Upper <br />Colorado River Basirt Compact Commission reported that the present use in <br />Western Colorado at sites of use was 1,019,087 acre-feet a year (Record, <br />Volume III, p. 6, 39, computed by subtracting 43,713 from 1,062,800). ~t <br />is fair to say that :J:.hE) study of t.he Engineering Advisory CODmlittee is the <br />last made on the po~nt and was thorough andcoznplete. ProJl)i.nent engineers <br />of the Bureau of Reclarnation wQrked on the Epgineering Advj.sofj' Committee <br />and signed its report, <br />