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

Home Browse Search

Redlands Diversion Dam at this time, nor would there be special efforts to protect downstream water users, although indirect benefits to water users would be expected to occur dependent on water supplies. The need for a fish passage 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 Recovery Program would no longer serve as the reasonable way (reasonable and prudent alternative) to offset impacts of water development, and existing and future water development and use in Colorado could be adversely affected. 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 considered building the passageway over the Redlands Diversion Dam in different locations. Alternatives involving building the passageway directly over the diversion dam were eliminated because they would decrease the ability of the diversion to handle flood flows, could interfere with operation of the diversion, and could increase the potential for ice damage to the passageway. One alternative provided for the fish passageway leading into the Redlands Canal and included a pipeline from the canal into the Gunnison River. This alternative was eliminated because it would force the native fish to use an enclosed pipe to exit from the canal into the river and would probably increase the potential of fish to be lost in the downstream powerplant. Interim Water Agreement Three alternatives are being considered for the interim water agreement. These are, basically, two alternatives to provide water for the endangered fish from the Aspinall Unit with protection of historic water uses and one alternative to provide water for the interim agreement with no special protection of historic water uses: Alternative A (Protection of Basin Water Users through Operational Flexibility)- -The agreement would maintain flows of 300 cfs downstream from the Redlands Diversion Dam in July through October. Based on water supplies available, Aspinall Unit operation planning would try to maintain that flow in other months, much as is done under present conditions but would not be part of the water agreement. The agreement would -specify that during the Aspinall Unit operation meetings (held each year during January, April, and August), Reclamation would develop an operating plan and water release schedule that attempts to satisfy the needs of downstream Gunnison River mainstem water users senior in priority to the Aspinall Unit. Dependent upon current hydrologic conditions and the available water supply, Reclamation would implement an operating plan which removes the need for administrative calls by these senior water rights when making releases for endangered fish. If an operating plan cannot be implemented which removes the need for administrative calls, then the parties to the agreement may reduce the 300 cfs fish release in order to minimize administrative calls. Simply, this 0