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Description of Alternatives <br />Maximum Powerplant Capacity Alternative <br />Minimum Maximum Allowable daily Ramp <br />releases releases fluctuations rate <br />(CIS) (cfs) (cfs/24 hrs) (cfs/hr) <br />1,000 Labor Day 33,200 32,200 Labor Day Unrestricted <br />to Easter to Easter <br />3,000 Easter to 30,200 Easter to <br />Labor Day Labor Day <br />Daily and Hourly <br />Operations <br />This alternative was developed to allow use of the maximum powerplant <br />discharge capacity that resulted from the previously discussed 1987 uprate <br />and rewind. Operations under the Maximum Powerplant Capacity <br />Alternative would be the same as under the No Action Alternative except <br />that use of the full powerplant capacity (estimated flows of 33,200 cfs) <br />would be allowed. Monthly and annual operations, including flood <br />control, would be identical to those described under no action. Releases in <br />excess of 31,500 cfs would be possible only when Lake Powell's elevation <br />is greater than 3641 feet. This additional capacity would be used when <br />power demand is high-typically 4 hours or less. <br />Minimum releases would be at least 3,000 cfs from Easter to Labor Day <br />and 1,000 cfs for the remainder of the year. The range in daily release <br />fluctuations and ramp rates would be restricted only by the physical <br />capability of the generators. <br />RESTRICTED FLUCTUATING FLOWS <br />The restricted fluctuating flow alternatives were designed to provide a <br />range of downstream resource protection measures, while offering varying <br />amounts of flexibility for power operations. All four alternatives-high, <br />moderate, modified low, and interim low fluctuating flows-restrict daily <br />fluctuations at Glen Canyon Dam as compared to the No Action and <br />Maximum Powerplant Capacity Alternatives. Each alternative also <br />specifies ramp rate restrictions and minimum release requirements. <br />Within the constraints of the alternatives, maximum water releases would <br />be scheduled to coincide with times of peak electrical demand. Low <br />releases are made at night to maximize the amount of water available for <br />daytime generation and thus minimize expensive daytime power <br />purchases. <br />Glen Canyon Dam EIS Summary 21