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<br />. <br /> <br />inoperable because of a loss of power during spillway releases. <br />Generally, during average years of flow, 1,800 cfs will be discharged <br />through the spillway gates, and then only in the month of June. For <br />wet years of flow, the amount spilled may increase to over <br />12,500 cfs. The gated spillway can accommodate a 500-year flood flow <br />of 45,250 cfs with the gates fully open. Figure III-3 shows the <br />spi 11 way capacity at different gate openings. If di scharges from <br />both the bypass outlet and power outlets are combined with the <br />spillway di scharge, the flows through the dam wi 11 be 53,750 cfs, <br />which is 28% greater than the 500-year flood event. <br /> <br />A flood routing of the runoff hydrographs from the contributing <br />drainage area above the reservoir will yield a more complete set of <br />operating criteria for the gated spillway in the next phase of work. <br /> <br />. <br /> <br />E. POWER GENERATION <br />The Webster Hi 11 project is a run-of-river development using the <br />natural flows of the Colorado River for power generation. The <br />impoundment behind the dam serves to maintain a constant power head. <br />Because of the seasonal flows, power generation is limited by high <br />tailwater during the spring runoff and by low flows during the winter <br />months. It was determined that multiple-prope11er-type turbine units <br />would provide the flexibility needed to use a large portion of the <br />available flow. <br /> <br />The following criteria were developed for operation of the reservoir <br />to maximize energy production. <br /> <br />o In wet and average years of flow, the normal pool elevation of <br />5,250 ft will be maintained throughout the year. The tail water <br />will vary depending on the discharge from 5,178 ft at 1,000 cfs, <br />to 5,180 ft at 4,000 cfs, to 5,187 ft at 20,000 cfs. <br /> <br />o <br /> <br />In dry years, the stored water will be delivered to <br />in accordance with WWE's release schedule, with <br />reductions in available head for power generation. <br /> <br />purchasers <br />subsequent <br /> <br />. <br /> <br />3686-a/7 <br /> <br />III-7 <br />