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0061 3.13 ".II, . : " ;. J i volj1Jlles ranging between 50,000 acre-feet and 80iOOO acre,..feet usually occur in the winter. The maKimj1Jll depth of the reservoir 'is 276 feet with yearly fluc- tuations in water levels ranging between 20 and 60 feet. MaKimum surface water te~peratures of 640 to 680 F usually ocpur in late July or August, wh~le bottom temperatures during this sa~e period ran~e from 400 to 500 F (Finnell, 1977; Nesler, 1979). The reservoir usually becqmes stratified between May and July with a thermal gradient formed at depths o~ 12 to 30 feet (Nesler, 1979). Due to an abundance of gypSj1Jll in the reservoir basin, the water chemistry is characterized by relatively high alkalinity, hardness, pI!, and conductivity (Finnell, 1977; Yahnke, 1982). Measured nutrient levels are relatively low in the reservoir, maKimj1Jll concentrations usually occur in the spring or fall near the bottom; minimj1Jll values usually occur in July (Nesler, 1979). The configuration of the reservoir is infl~enced by the steep shoreline and the location of tributaries. The north shore of the reservoir is modera"" tely steep and has four large bays (Ruedi/Pond Creeks, Hanson Gulch, Smith Creek, and Freeman Creek). These bays provide important habitat for aquatic organisms as a result of more diverse bottom sUQstrates and eKtensive macrop~yte growth. In contrast, the south shor~ of the reservoir is steep with fewoperennial tribut~ies. The section of the Fryingpan River in the project study area is a 14-mil,e segment eKtending from Ruedi Dam at an elevation of 7,766 feet downstream to its confluence with the ~aring Fork River near,Basalt at an elevation of approKimately 6,600 feet (Figure 3,2). GeneraltY, the physical and chemical I characteristics of this section of the Fryingpa1 River represent good quality habitat for trout. Based on a system that rate$ important habitat features in Rocky Mountain trout streams (Binns, 1982), the!Fryingpan River ranks as,a good quality stream for most attributes (Table 3.7). A brief description of the more i~ortant 'physical/chemical characteristics is provided below. Of the physical and chemical. parameters mei!.sureC! in the Fryingpan River (Appendix B, Table B.1), temperature appears tojbe the only potential limiting , factor to the fisheries. Due to the deep relea~e of water from the reservoir, mean monthly summer temperatures in the river h~ve decreased about 150 F at the dam site and 90 F near Basalt compared to Pre-dam records (Nehring and Anderson, 1981). Low water temperatures in the spring (370 F to 410 F) >