Electrical Power for Valdez and the Copper River Basin-1981

effects on the salmon run and the resultant fishery are being assessed.A stream gage has been installed to aid in the determination of existingwinter flows. A recording thermograph has been in operation since 1979in Allision Creek. The data for that period is included in Appendix E.Two additional thermographs will be installed to determine spawninggravel temperatures within the stream and the intertidal area.Mitigation includes providing a two tailrace system which would dischargefully into Allison Creek in the summer. Winter discharge would be toPort Valdez with partial diversion to Allison Creek to maintain adequate; nstream flow.Other impacts include disturbances to wildlife during the constructionphase, clearing of approximately 22.5 acres of spruce/hemlock forestfor the transmission rigllt-of-way, and decreases in the visual quality ofthe area. For further information on project impacts, refer to the environmentalimpact statement.~Ii ti gati on:Proposed mitigative measures are for a tailrace to Port Valdez inaddition to the one to Allison Creek. The rationale behind the twotailrace system is to divert winter powerhouse releases directly to PortValdez, thus reducing water temperature impacts on Allison Creek duringsalmon egg incubation. Mitigative costs for the additional tailrace andgating systems are $925,000 including 20 percent contingencies, 8 percentengineering and design, and 8 percent supervision and administration.Annual costs were calculated at $68,300.Determining the monetary value of the Allison Creek fishery is notfeasible. Population estimates are not complete and reflect minimal datacollection. Biomass originating from salmon production in Allison Creekis large enough to be an important contributor to the Port Valdez derivedfood web. Fish originating from Allison Creek also add to the commercialand sport fisheries. Esthetic values and other intangibles are alsoillportant to the human envi ronment of the study area. The spawni ngactivity can be observed where the creek is crossed by the Dayville Road.The probability of losing of the fisheries resource of Allison Creekis high without mitigation. This loss would have an effect on the PortVal dez ecosystem and to the human envi ronment of the study area.Implementation Responsibilities:The United States would design and construct the lake tap,powerplant, and transmission facilities. Project operation would besupervised by personnel from the local utility from a centralizedoperati ons control center. Project mai ntenance woul d be performed byFederal maintenance/operators assigned to the project who would besupplemented by utility maintenance personnel. These individuals wouldoperate the project under emergency situations. Overall projectadministration including power sales contracts, billing, accounting, andannual inspections would be provided by the Alaska Power Administrationheadquarters office in Juneau.38