8234 - Laserfiche WebLink

Home Browse Search

228 t A RK 184.6 Kenney Reservoir RK 167 8 RK 176.9 Rangley Taylor Draw Dam RK 115.5 Rio Blanco Lake RK 243 NYONING 60 S YDouglas Creek Piceance Creek ? Utah Colorado 30 kilometers Utah Colorado Fig. 1. White River/Kenney Reservoir study area. River kilometers (RK) are demarcated from the confluence of the White and Green rivers in Utah (see inset). Introduction Dams and reservoirs have had profound effects on the ecology of the Colorado River system (Mullan et al. 1976, Stanford & Ward 1986a, b, c). Its endemic fishes have beer. negatively affected by modifica- tions resulting from impoundments (Behnke & Benson,' Hickman 1983, Holden & Stalnaker 1975, Miller 1946,1961, Minckley & Deacon 1968, Tyus et al. 1982, Vanicek et al. 1970). Further, competition with non-native fish species, many of which thrived in the modified environments within and down- stream from reservoirs, may also have contributed to the decline of native species (Stanford & Ward t986c). Effects of damming a river have been classi- fied as immediate and delayed (Holden 1979). Im- mediate effects include those that become apparent when a dam becomes operational. Delayed effects become evident several years after dam completion Behnke. R.J. & D.E. Benson. 1980. Endangered and threat- ened fishes of the Upper Colorado River Basin. Cooperative Ex- tension Service Bulletin 503A. Colorado State University. Fort Collins. 34 pp. (Holden 1979). The closure of Taylor Draw dam on the main stem White River in October 1984, proved to have both immediate and delayed impacts on the river's fish community. Immediate effects included blockage of up- stream migration to 80 km of river known to con- tain Colorado squawfish Ptychocedus lucius (Mar- tinez,'` Chart 1986), a large piscivorous minnow list- ed as endangered by the U.S. Department of the In- terior. Summertime aggregations of adult Colorado squawfish below the dam following its closure were believed to be composed of post-spawners return- ing to home ranges from spawning sites in the Green and Yampa rivers. The death of several of these adult fish in 1985 due to angling activity below the dam prompted an emergency regulation pro- hibiting angling in this area (Martinez). In addition to these immediate effects on Colora- do squawfish, the fish community of the White Riv- er also experienced both immediate and delayed ' Martinez. P.J.1986. White River Taylor Draw Project pre- and postimpoundment fish community investigations. Colorado Di- vision of Wildlife. Fort Collins. 121 pp.