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<br />G. <br /> <br />Category: <br /> <br />Control: <br /> <br />o <br />o <br />r":l <br />,~ <br />CO) <br />-J <br /> <br />Purpose: <br /> <br />Flood Control Releases (incorporated in operating rule) <br /> <br />Flood control releases are to be handled as a spike (high magnitude, short <br />duration), released when flood control rules require, except that the <br />release shall not occur earlier than September I. If an earlier release is <br />required, extend the duration of the peak of the release hydrograph. A <br />ramp up and ramp down of 1,000 cfs per day should be used to a <br />maximum release of5,000 cfs. If the volume to release is less than that <br />required to reach 5,000 cfs, adjust the magnitude of the peak accordingly, <br />maintaining the ramp rates. Multiple releases may be made in one year. <br />These spike releases shall be used in place of adjustments to base flow. <br /> <br />Historically, flood control releases were made by increasing fall and <br />winter base flows. This elevates flows above the optimum range for <br />nursery habitat. Periodic clean-water spike flows improve low velocity <br />habitat quality by flushing sediment and may suppress red shiner <br />abundance. <br /> <br />Table 9-1. Frequency distribution table for flow/duration recommendations <br /> <br /> Discharge <br />Duration <br /> > 10,000 cfs >8,000 cfs >5,000 cfs >2,500 cfs <br /> Average Frequency <br />I day 30% 40% 55% 90% <br />5 days 20%' 35% 50% 85% <br />10 days 10% 33%' 48% 80%' <br />15 days 5% 30% 46% 70% <br />20 days 20% 45%' 65% <br />30 days 10% 38% 60% <br />40 days 25% 50% <br />50 days 20% 45% <br />60 days 10% 40% <br />80 days 5% 30% <br /> <br />I Primary criteria shown in bold. <br />