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result in additional releases from the dam to increase peak flows. However, Yampa River runoff will remain the most important influence in producing an elevated runoff pulse in the mainstream Green River. In addition to altering the natural hydrograph of the Green River, Flaming Gorge Dam has eliminated sediment transport from upstream reaches and introduced cold water into a warmwater river. The effects of these alterations to physical habitat used by the native fishes are ameliorated gradually with distance below the dam. Although native fishes have been displaced by cold water immediately below the dam, the endangered fishes continue to use warmer reaches in Browns Park and Lodore Canyon. Colorado pikeminnow continue to use mainstream habitat in Lodore Canyon and venture into Browns Park. Some adult razorback suckers occupy the lower part of Lodore Canyon. Furthermore, bonytail have been reintroduced into Browns Park. This part of the river system is not now included as critical habitat, but actual and potential habitat use by endangered fishes suggests that a review would be in order. The White River is heavily used by adult Colorado pikeminnow, especially in the 20 miles above the mouth and immediately below Taylor Draw Dam. Although critical habitat is designated as far upstream as Rio Blanco Lake, about 32% of historic habitat is not accessible to the fish due to Taylor Draw Dam, -which poses an impassible barrier. Kenney Reservoir, impounded by the dam, is a major source of nonnative fishes that move downstream into high priority recovery areas, and is rapidly filling with sediment. Various alternatives have been evaluated for reducing the sediment impacts, and several of these could benefit Colorado pikeminnow recovery efforts. Serious consideration should be given to implementing measures to restore passage of Colorado pikeminnow upstream of the dam, including various alternatives that incorporate bypasses and dam removal. The Duchesne River is used by Colorado pikeminnow and razorback- sucker, especially near the mouth, although an occasional fish has been recorded much further upstream. Critical habitat for the razorback sucker now includes 2.5 miles of river above the mouth. Recent captures of Colorado pikeminnow and razorback sucker warrant further evaluation of the Duchesne River for its recovery potential. Habitat conditions have been altered significantly by flow depletions and introductions of nonnative fish species. The Duchesne River provides a steady supply of nonnatives to mainstream habitat in the Green River. The Price and San Rafael rivers make relatively minor contributions to flow and sediment in the Green River system, but both furnish some habitat used by the endangered fishes. A few adult Colorado pikeminnow have been recorded in the Price River, and larval razorback suckers and juvenile pikeminnow have been found in the lower San Rafael River. Critical habitat has not been designated in either river, except that the mouth of each stream is in the 100-year floodplain of critical habitat designated for the Green River. ix C