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<br />, <br /> <br />e <br /> <br />e <br /> <br />e <br /> <br />Enclosure 1 <br /> <br />Summary of Recommendations For Flows in The IS-Mile Reach During <br />October-June For Maintenance and Enhancement of <br />Endangered Fish Populations of The Upper Colorado River <br /> <br />The report provides flow recommendations for October through June based upon <br />biological and hydrological criteria described in detail in the report. <br /> <br />October <br /> <br />Mean monthly flows have decreased during the last 30 years to about 61 percent <br />of what they were in the early part of the century. Flow decreases in October <br />do not appear to have made a major difference in habitat use and flows between <br />700-1,200 cfs are recommended to maintain adult habitat during October. These <br />recommendations are currently being met in most water years. <br /> <br />November to February <br /> <br />Winter flows have increased over the past century. There appears to be little <br />problem with existing winter flows, beginning in November and running through <br />February. During this period the recommendations are for flows to not fall <br />below historic levels i.e., between 1,000 and 2,000 cfs, averaging about <br />1,470 cfs. If operation of upstream storage facilities allowed, a <br />redistribution of winter flows to provide additional water in the spring would <br />be beneficial. <br /> <br />March <br /> <br />March is viewed as a transition month, flows have increased on average during <br />March by about 220 cfs since the early part of the century. Flows now average <br />around 2,000 cfs. The report recommends maintaining flows at this level based <br />upon deep-water habitat needs of razorback suckers. <br /> <br />April, May, and June <br /> <br />Spring flows during April, May, and June are designed to meet the habitat <br />requirements of the fish, to meet the need for flushing and channel <br />maintenance flows, and to enhance the reproductive success of Colorado <br />squawfish. High spring flows are necessary to create and maintain habitat for <br />adult Colorado squawfish both within the IS-mile reach and in the important <br />reaches of the Colorado River downstream. These high flows not only create <br />the diversity of habitat required by adult fish but also the backwater nursery <br />habitat that is critically important to the young. Spring peak flows also <br />have been demonstrated to be useful in reducing the distribution and abundance <br />of nonnative fish species which are detrimental to the endangered fish. <br />Perhaps most importantly, the report indicates that there is a statistically <br />significant relationship between the magnitude of peak spring flows and the <br />production of larval Colorado squawfish. Specifically, the production of <br />young-of-the-year Colorado squawfish is highest following a spring with peak <br />flows of 30,000 to 40,000 cfs at the Colorado-Utah Statel ine. , . <br /> <br />Spring flows recommendations are broken down into a daily peak flow for each <br />year and a mean monthly flow for each of the spring months. In wet years the <br />