Electrical Power for Valdez and the Copper River Basin-1981

within the local community. The impact of the employees on the localeconon~ would probably be minor; however coupled with the construction ofthe city dock and the ALPETCO plant, the cumulative effects may cause asurge in the Valdez econorr~. Proposed construction times indicate theAllison project would be built after the above projects are completed.The power generated at Allison Creek may have a long term positive impacton the economy of Valdez and Glennallen area. Initially the cost of thepower would De approximately equivalent to the present power costs basedon the October 1980 cost estimate. Once constructed, future priceincreases would be related to tne increase in operation and maintenancecosts. Increases with diesel generation is directly related to the priceof diesel, which is escalating rapidly.The operation and maintenance of the facility would require very fewpersons. ana their presence would have little impact on the socioeconomicstructure of the study area.4. Cultural ResourcesThere are no cu ltura 1 resources in tne affected area, thus no impacts.E. MITIGATIONThe proposed hydroelectric project on Allison CreeK may eliminate thenatural runs of both pink and chum salmon over a period of time.Although the fiShery resource of Allison Creek is not large in comparisonwith other river systems in Prince William Sound, the resource should bemaintained as close to its preconstruct ion strength as is practicable.A two tailrace system was devised to regulate the amount of water beingreleased into Allison Creek. The system consists of an additionaltailrace which would empty directly into Port Valdez. Both tailraceswould incorporate a gating mechanism which could regulate the amount offlow through a particular tailrace. Thus, all the water, any portion ofthe water', or none of Ule water can be regu 1 ated through eithertailrace. The upper powerhouse location would help protect both theintertidal and Allison Creek fisheries. This was one of the contributingfactors for the selection of the upper powerhouse site as the preferredalternative.The discharge from the powerhouse would be diverted into Allisen Creekduring the periods of salmon spawning to provide adequate flows forspawning. During the winter monthS when temperature is critical for eggincubation and emergence, the discharge would be diverted directly toPort Valdez. A 4 cfs minimum during the winter months was suggested byU.S. Fish and Wildlife Service for maintenance of egg incubation. Anadaitional 3/4 cfs is required for Alyeska's water supply. If naturalflows are below 5 cfs, the tailrace to Allison Creek can be utilized toaugment that portion belo~ 5 cfs.Studies on similar ldkes in Alaska indicate that bottom temperaturesduring the spawning season are higher than 4°C used in this report.IfE1S- 15