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<br />Draft Fmal Completion Report to UDWR for Contract #93-1070. Amendment 3 <br /> <br />18 <br /> <br />others (1990), in a study to discern the discharge that maximized availability of nursery habitat, measured the changes <br />in habitat availability in relation to discharge over a 4-month period. While the backwaters in Pucherelli' s (1990) study <br />were classified as being associated with either a bank or bar, the study did not address the relationship between <br />geomorphic features and habitat availability nor the temporal variation that might occur in that relationship. <br />Colorado squawfish use habitat formed by within-channel geomorphic features. Consequently, quantification <br />of channel response to flood passage and base flows must also address changes to within-channel geomorphic features if <br />effects on Colorado squawfish recruitment are to be discerned. This study seeks to improve our understanding of the <br />relationship between discharge and available habitat by developing an understanding of the physical processes <br />underlying the changes in within-channel morphology, and the impact these changes have on the distribution and <br />availability of nursery habitat. <br />Scientifically-defensible flow recommendations need to include a suite of flows including periodic high flows <br />of sufficient magnitude and duration to maintain channel width, scour stabilizing vegetation and enhance channel <br />complexity, and base flows that optimize the availability of optimal habitat. The long life of the Colorado squawfish and <br />the other endemic Colorado River fishes are adapted to not require successful recruitment each year for species survival <br />(Minckleyand Deacon. 1991). Consequently, the large discharges necessary to maintain channel form may reduce <br />habitat availability for a year, but nevertheless may be viewed as a viable river management tool. <br />In summary, this research addresses the efficacy of current flow recommendations to form, maintain. and <br />maximize the nursery habitat available for endangered fishes in the Green River near Ouray, and suggests alternate <br /> <br />methodologies for flow management. <br />