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3 I I I I I I I I I I I I I I I I I I I (UDWR) to provide necessary flows for the tailwater trout fishery, and maximum powerplant releases are constrained by generator output capacity and reservoir elevation. The dam also has the capacity to release up to 4,000 cfs (113 cms) through two river outlets (jet tubes), and an additional 28,800 cfs (816 cms) through the spillway. Flow regulation is ameliorated with distance downstream from the dam, and by inflow from several major tributaries, including the Yampa, White, Duchesne, San Rafael, and Price rivers. The Green River and its tributaries historically supported 13 species of fish native to the upper Colorado River basin (Tyus et al. 1982). Eight warmwater species were native to the river below Flaming Gorge (Table 1), including Colorado squawfish (Ptychocheilus lucius), humpback chub (Gila ~), bonytail (Gila elegans), roundtail chub (Gila robusta), speckled dace (Rhinichthvs osculus), razorback sucker (Xyrauchen texanus), flannelmouth sucker (Catostomus latipinnis), and bluehead sucker (Catostomus discobolus) (Vanicek 1967). Following construction of Flaming Gorge Dam in 1962, distribution and abundance of these eight warmwater species were greatly reduced in areas inundated by the reservoir and affected by coldwater releases. Green River fishes below Flaming Gorge Dam--trout in the tailwaters and natives funher downstream--are variably affected by altered flow, modified water chemistry, and large numbers of non-native fishes. Colorado squawfish, humpback chub, bonytail, and razorback sucker are classified as endangered, under the Endangered Species Act of 1973, as amended, and roundtail chub and flannelmouth sucker are candidate species. Status and opportunities for recovery of these native Colorado River fishes may be related to winter conditions, as affected by releases from Flaming Gorge Dam.