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the face of the dam, extending downward to each of the three <br />fixed-elevation inlets. Shutter gates along the face of each extension <br />can now be opened to withdraw water from selected elevations in the <br />reservoir's water column. Thus, during summer, water temperatures <br />optimal for trout growth (12.2°C or 54°F) are released to the tailwater. <br />In spring and fall, tailwater temperatures are maximized by raising <br />penstock inlet elevations to as near the surface as possible. Warmest <br />temperatures (4°C or 39°F) are available deep in the reservoir in winter, <br />when water is drawn into the fixed penstock inlets, bypassing the inlet <br />extensions. <br />BOR funded this study for the initial purpose of evaluating the <br />response of the tailwater fishery to the penstock modifications. From <br />September 1978 - November 1980 the study was focused primarily upon <br />increase in growth rate of trout and its ramifications to the <br />sportfishery. However, it became apparent during this period that the <br />sportfishery response to the penstock modification was constrained by <br />poor winter survival of stocked fingerlings. Concurrently, modifications <br />to the dam that would increase hydroelectric capacity and peak discharge <br />rates were under consideration. In 1980, therefore, BOR funded a second <br />phase of research to identify factors influencing trout survival. This <br />second phase of work, which ran from fall of 1980 - November 1982, <br />required a wide range of study elements and methodologies, including <br />angler creel surveys, fish tagging, surveys of physical habitat, <br />measurement of trout microhabitat selection, and observations of fish <br />behavior. The entire field study period was from September 1978 - <br />November 1982. Angler harvest data for 1983-1985 are presented in this <br />report to track survival of trout originating during the 1978-1982 study <br />years. <br />-10-