Draft Environmental Assesment and Finding of No Significant Impact Gunnision River Activities February 1995

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The riparian lands, particularly those upstream from the diversion dam, provide valuable wildlife habitat. Forested wetlands in western Colorado are very scarce and support a disproportionately high percentage of wildlife in terms of number of species and number of individual animals. This type habitat is rapidly being lost to sand and gravel development, recreation development, and floodplain alterations. The lower Gunnison River is an important wintering area for waterfowl. Impacts Under the No Action Alternative and the proposed actions, there will be alterations of riparian vegetation and wildlife habitat upstream from the Redlands Diversion Dam as private gravel operations are started. River flows downstream from the diversion dam will occasionally be very low, resulting in poor habitat conditions. Under the proposed alternative, no significant impact on wildlife species is projected due to the small acreage involved with the fish passageway and due to plans to replace vegetation losses. It is recognized that altered operation of the Aspinall Unit can affect fisheries in Blue Mesa Reservoir and in the Gold Medal trout fishery downstream. The proposed interim water agreement will involve releases of water from the reservoir and maintenance of these flows past the Redlands Diversion Dam. These changes are shown in Tables 1 through 4 on pages 18 and 19, and in Attachment E. Resultant effects on fish and wildlife resources will not be significant under Alternatives A and B because changes in river flows and reservoir content are minor in most years as can be seen from the tables. In a series of dry years exemplified by 1990, the reduction in Blue Mesa Reservoir's water content would reduce productivity of the reservoir. There will be some benefits to the trout fishery in the Black Canyon and Gunnison Gorge areas as low summer flows would occasionally be supplemented over existing conditions. Improved flow regimes in the Gunnison River downstream from the Redlands Diversion Dam in low flow periods will benefit both terrestrial and aquatic resources down to the confluence with the Colorado River by better supporting associated riparian vegetation communities and increasing the wetted perimeter of the river channel. Endangered Species Existing Conditions The large rivers of the Upper Colorado River Basin are home for four native fish species that are listed as endangered under the Endangered Species Act. This means that the fish are in danger of extinction. The four fish are the Colorado squawfish (Ptychocheilus lucius), the razorback sucker (Xyrauchen texanus), the humpback chub (Gila cypha), and the bonytail chub (G. elegans). A variety of factors -- diversion of flows, introduction of non - native species, floodplain alterations, barriers to migration, and water quality- -have significantly changed the rivers these fish live in and their numbers have dropped sharply. In the Gunnison River (McAda 21