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3.17 Water-quality data from the Glenwood Springs to Cameo section of the Colorado River indicate that water quality is good (Appendix B, Table B.5). Dissolved solids concentrations are moderate during the low-flow periods (September-April) and suspended solids concentrations are high during the peak flow period (April-August). Water temperatures range from about 524F in April to 71OF in September. Aquatic habitats have been characterized in the Colorado River between Palisade and Rifle (Valdez et al., 1982). In the section from DeBeque to Rifle, shallow- to moderate-depth runs and riffles with numerous pools and eddies are the predominant habitat types. Backwater areas are uncommon. Maximum depth is about 18 feet with a mean depth of about 2 feet. Bottom substrates consist mainly of gravel, cobbles, and boulders with some silt and sand. The section of the Colorado River from Palisade to DeBeque has been altered considerably by Interstate Highway 70 and the Union Pacific Railroad rights of way. Habitat in this stretch consists mostly of runs, pools, eddies, and few backwaters. Banks lined with boulder riprap are common in this stretch. Substrate is similar to the DeBeque-Rifle segment except that sand and silt areas are limited to the small reservoir created by the Government Highline Dam. The dam also seems to be an effective fish barrier restricting upstream movement. Maximum and mean depths in this segment are 17 and 6 feet, respectively. 3.3.2 Fish Fish populations in Ruedi Reservoir are comprised mainly of salmonid spe- cies (Table 3.8). Of the seven species collected in previous surveys, five are game fish: rainbow trout (Salmo glirdneri),'brown trout (Salmo trutta), brook trout (Salvelinus fontinalis), lake trout (Salvelinus namavcush), and kokanee salmon (Oncorhvnchus nerka) (Finnell, 1977). Colorado River cutthroat trout (Salmo clarki aleuriticus) were stocked in 1972, but no specimens have been collected in recent surveys (Nesler, 1979). Habitat requirements for these salmonid species are summarized in Table 3.9. The only non-salmonid species collected in the reservoir are bluehead sucker (Catostomus discobolus) and mottled sculpin (Cottus bairdi) (Nesler, 1979; ERT, 1982). _ The composition of gillnetting surveys in Ruedi Reservoir during 1970, 1973, 1977, and 1978 is quite similar (Finnell, 1977; Nesler, 1979). Brown trout dominated the catch in all years with percent composition ranging between 42 percent in 1978 and 49 percent in 1970-1973. A survey in 1978 yielded the