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4 High il~~ test A fourth objective was added after the first year of study had been completed. This was to monitor the effects on the fish (in terms of microhabitat) during a proposed test of winter high flow releases during 1982. Fish microhabitat data were again collected by species, life stage, . and physical activity as was done in 1981. The data were stratified into three time periods during the winter 1982: prior to high flows (January), during high flows (February), and after high flo~s ~:Idrch - April). ~te description Phys i c a 1 The study area was defined as extending from the dam down- stream 18 km to Red Creek (Figure 1). Microhabitat data were collected primarily from the first 7 km below the darn. Releases frrnn the dam normally fluctuate from 800 to 4300 cfs (22.6 - ... 121.8 m3/sec). An intensive study site was selected by USBR per- sonnel approximately 0.4 km below Pipe Creek (Figures 1 and 2). They established and mapped ten transects across this site to provide the physical data for the IFG-4 hydraulic model. These same transects were also used to provide vegetative infon~ation. Water temperatures in the river are regulated during the summer to 13 C at the dam by adjustable penstock intakes. During the winter, temperatures drop to a minimum of 4 C at the dam. The stream banks consist primarily of rock and rubble with little riparian vegetation. The banks are usually stable with