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Action and Alternatives A, B, and C changes in Aspinall Unit operations would still be recommended in the future for protection and recovery of endangered fish. Construction and operation of the fish passageway is intended to correct the fish movement problem for the Gunnison River. It is projected that the endangered fish and other native fish will begin to move above the Redlands Diversion Dam on the Gunnison River in the years following installation of the passageway. The passageway will essentially open over 50 miles of river for these fish, with the plan that this will aid in eventually developing self-sustaining populations. Adult and subadult fish are expected to migrate back downstream over the Redlands Diversion. Larval fish may also drift over the dam. Larval fish will be monitored to determine their movements. The fish passageway will be designed and operated to prevent non- native fish from moving upstream, reducing or eliminating the problem of introducing more non- natives to the Gunnison River. This is important as there are minimal numbers of predatory non-native fish such as channel catfish and bass upstream from the Redlands Diversion Dam. Provision of water under the interim agreement is a critical element in meeting the goal of self- sustaining populations. The agreement will assure a dependable water supply for operation of the passageway and will improve flows in the 2.3 mile reach of the Gunnison River downstream from the Redlands Diversion Dam. The flow in this reach occasionally drops below a level that can support the movement of fish. In extreme drought years such as 1977, flows would not be supplemented as much below the Redlands Diversion. In cases such as this, the fish might remain in the Colorado River where water conditions would be better. No "take" (harming) of endangered fish species is anticipated by the construction and operation of the fish passageway. The screening devices described in Chapter 2 should prevent migrating fish from entering the city of Grand Junction pumping plant intake. The location of the fish passageway on the inside of a major river bend and the perpendicular orientation of the fish passageway entrance to the flow of the river will also prevent "take" of fish moving back downstream. The Service concluded that they do "not anticipate that the proposed action will result in any incidental take of the endangered fishes" (Fish and Wildlife Service, 1995). Presently, potential effects of selenium levels in the river on endangered fish are not known. Studies are being done to look at the effects of water quality parameters, including selenium, on the fish and will help answer these questions. In summary, the passageway is designed to result in a self-sustaining population of razorback suckers and Colorado squawfish in the Gunnison River. It is recognized that there are some unknowns in this plan. For example, fish passage structures of this type have not been used for these species before and actual use will only be determined by monitoring actual operations. Also habitat conditions above the diversion have been affected by factors other than the diversion--water quality has changed from historic conditions, flow regimes have been altered, channelization has occurred, and non-native fish are present. Some of these concerns are simultaneously being addressed by the Recovery Program. 30