Final Environmental Assesment and Finding of No Significant Impact Gunnision River Activities June 1995

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at a range of flows, and 300 cfs provides minimum to adequate depths for fish movement. The 300 cfs is necessary to maintain approximately 1 foot -of depth through the critical shallow areas of the river downstream from the Redlands Diversion Dam. A portion of the same water will be used to operate the fish passageway. The Service and the State of Colorado will study and evaluate the effects of the releases on occupied habitat of endangered fish in the Gunnison River. Recommendations will be made, based on these studies, on development of a long -term water supply contract. In addition, the effects of the interim water agreement on other water uses in the basin will be monitored, thus providing important data for use in developing a long -term contract. Appendix B highlights provisions of the draft agreement. Three alternatives were considered for how the water agreement will address historic water use patterns that have developed since the completion of the Aspinall Unit and these are discussed below. Alternative A, which provides fish flows of 300 cfs from July through October and historic levels of protection to water users based on water supplies and existing contracts as discussed below, is the preferred alternative. Under all alternatives, including No Action, water would be available for sale from the Aspinall Unit for municipal, industrial, irrigation, or other purposes. Alternatives No Action On any program, the "No Action" alternative exists. Under this alternative, a fish passageway would not be constructed under the Recovery Program and the interim water agreement would not be executed. There would be no special effort to maintain a flow of 300 cfs below the Redlands Diversion Dam at this time, nor would there be special efforts to protect senior water users downstream of the Aspinall Unit; however, water users would be expected to continue to utilize Blue Mesa releases dependent on water supplies. The need for a fish passageway would remain and a passageway could be constructed under other programs. Under No Action, the endangered fish studies on the Gunnison River would still continue, leading to recommendations for changing Aspinall Unit operations to protect the fish. However, the absence of a fish passageway at the Redlands Diversion could impair the Recovery Program's ability to act as the "reasonable and prudent alternative" to offset the impacts of water use and development, and as a result both existing and future water use could be adversely affected under the Endangered Species Act either economically or in ability to use water. Fish Passageway Alternative designs for the fish passageway were also considered, and several different types of passage structures were appraised. All but one of the alternatives had a vertical slot and orifice in each baffle. The primary variable of the different alternatives was the location of the passageway in relation to the diversion dam. Several alternatives were considered which involved building the passageway over the Redlands Diversion Dam in different locations. These 2