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<br />. <br /> <br />Over 3,500 gigawatt-hours of electrical energy used in both the Upper and Lower Basin <br />Stales would be lost, <br /> <br />. <br /> <br />Recreational benefits associated with Lake Powell total about 3 million visitor days per <br />year. There are significant economic impacts associated with the loss of this recreation <br />industry , <br /> <br />. <br /> <br />The reservoir fishery would be lost, <br /> <br />. <br /> <br />The cold-water trout fishery below the dam would be lost. <br /> <br />. <br /> <br />Current operations of the dam provide for stable and predictable white-water river running <br />activities during periods of high runoff (flows greater than 45,000 cfs for 6 to 10 weeks) <br />and during periods of drought or low runoff <br /> <br />Additional points of interest related to the Glen Canyon Institute proposal to drain Lake <br />, Powell to minimum power head and maintain at that elevation (el 3,500): <br /> <br />. <br /> <br />The proposal would leave ap~roximately 6 mafofstorage in Lake Powell, of which about <br />2 maf would be dead storage, The 4 maf of active storage capacity would be required to <br />maintain minimum power head and would only be useable to meet downstream demands if <br />the power system were shut down, <br /> <br />. <br /> <br />Only present levels of use of Colorado River waters could be maintained wilhout <br />significant and extreme risk to both water supply and power supplies, About 1,7 maf of <br />~ use of Colorado River water would have to be forgone in the Upper Basin, <br /> <br />. <br /> <br />Power generation at Glen Canyon Dam would be reduced by a significant amount, <br />possibly about 30%, Power generation at Hoover Dam would increase some lesser <br />amount, with the net system energy production showing a reduction, <br /> <br />. <br /> <br />Twenty miles of stream channel would be recovered in each of the Colorado mainstem and <br />San Juan River drainages, Approximately 15 miles of the Escalante River would be <br />recovered. Some of this benefit would be lost in years of above average runoff as the <br />runoff is temporarily stored at Lake Powell due to insufficient release capacities (45,000 <br />cfs), As much as 70 feet of vacated reservoir space would be required to pass the runoff <br />experienced in 1983 or 1984 (resulting peak reservoir elevation would be 3570 feet), <br /> <br />. <br /> <br />Evaporation at Lake Powell would be reduced by about 65% (about 320,000 at), but <br />evaporation would increase by 9% (70,000 at) at Lake Mead, leaving a net decrease in <br />evaporation of20% (250,000 at) of the total system evaporation, <br /> <br />2 <br />