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Riparian corridors in the semi-arid climate of western Colorado provide perhaps the most limited and most valuable wildlife habitat in the area. The riparian habitat provides valuable nesting and migration habitat for a number of birds. Limited waterfowl nesting occurs along the Gunnison River, but a significant winter waterfowl population uses the river. Regulated flows downstream from the Unit have affected riparian areas in two ways: reduced scouring flows have expanded areas of riparian shrubs, and in the Park, box elder vegetation and other riparian species; and the reduced high flows have limited cottonwood regeneration, primarily along the lower Gunnison River. Waterfowl use would be affected by increased ice formation under the increased minimum flows, but this is not expected to be a significant impact on wildlife. With the NPS desired flows, riparian vegetation would probably be reduced along the river in the Black Canyon and Gunnison Gorge, while in the lower river this would probably occur to a lesser extent and cottonwood regeneration would benefit. Backwater and oxbow-type wetland maintenance would benefit from increased spring flows. Changes in wildlife habitats and vegetation have not been analyzed in detail. Endangered ed Species The Upper Colorado River Endangered Fish Recovery Program recently issued draft flow recommendations to recover endangered fish in the Gunnison River. The lower 57 miles of the Gunnison River have been designated as critical habitat for the Colorado pikeminnow and the razorback sucker. Reclamation analyzed the impacts that the NPS desired flows might have on the draft flow recommendations for endangered fish. The endangered fish flow recommendations call for mimicry of the natural hydrograph. Minimum flows (300 cfs) downstream of the Redlands Diversion Dam and fish passageway are recommended, along with base flows for critical habitat. In general, both the endangered fish recommendations and NPS desired flows call for a high spring peak flow. Under the base model run, the preliminary recommendations for endangered species peak flows are met approximately 33 percent of the time. In the model runs to meet the NPS desired flows, this percentage increases to 58 to 75 percent of the time. Thus the NPS desired flows would have a beneficial effect on meeting peak flow needs for the endangered fish. Meeting base flows for the endangered fish is difficult in dry years under all model runs; however, meeting the endangered fish base flows overall is only slightly decreased under the NPS desired flow model runs. The recommended endangered fish flows downstream from the Redlands Diversion would be met less frequently under the NPS desired flow model runs than under the baseline run. Reductions below the 300 cfs minimum would occur approximately 8 percent more frequently, with volume shortages increasing roughly 20 percent. This will need to be further analyzed to determine significance; however, most shortages occur in winter and early spring and may have minimal effects on the endangered fish. 10