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<br />G. <br /> <br />Category: <br /> <br />Flood Control Releases (incorporated in operating rule). <br /> <br />. <br /> <br />Control: <br /> <br />Handle flood control releases as a spike (high magnitude, shon duration) and <br />release when flood control rules require, except that the release shall not <br />occur earlier than September 1. If an earlier release is required, exte:Jd the <br />duration of the peak of the release hydrograph. A ramp up and ramp down <br />of 1 ,000 cfs per day should be used to a maximum release of 5,000 cfs. If the <br />volume of water to release is less than that required to reach 5,000 cfs, adjust <br />the magnitude of the peak accordingly, maintaining the ramp rates. Multiple <br />releases may be made each year, These spike releases shall be used in place <br />of adjustments to base flow. <br /> <br />Purpose: <br /> <br />Historically, flood control releases were made by increasing fall and winter <br />base flows. This elevates flows above the optimum range for nursery habitat. <br />Periodic clean-water spike flows improve low velocity habitat quality by <br />flushing sediment and may suppress red shiner and fathead minnow <br />abundance. <br /> <br />. <br /> <br />Operating rules for Navajo Dam were developed to assist the Bureau in operating the dam to meet <br />the flow recommendations. These rules determine the timing and size of release flows to maximize <br />the ability of the river to meet the flow recommendations. Releases to produce a peak spring flow <br />are not made every year because saving water, (1) for human use, and (2) to make a larger peak in <br />a future year, is incorporated into the rules. The flow recommendations, and use of the operating <br />rules, will provide flows in the San Juan River that are conducive to recovery of the two endangered <br />fish species. As presently configured, the flow recommendations will also allow for a significant <br />amount of future water development in the basin (122,000 acre feet (at) beyond present). <br /> <br />. <br /> <br />SJRJP Biology Committee <br />16 September 1998 <br /> <br />S-8 <br /> <br />Executive Summary <br />Draft Aow Report <br /> <br />1 <br /> <br />