Electrical Power for Valdez and the Copper River Basin-1981

Waterfowl and water related birds found at the mouth of Allison Creek mayavoid tne immediate area during the construction phase with no long termadverse effects expected. The possible increase of freshwater into thebay may cause minor shoreline icing during winter months and coulddecrease the available habitat.Slignt changes in tne marine habitat would occur through the increase ofwinter freshwater and the placement of 5 cubic yards of riprap. Themarine habitat changes are considered minor.Pressure Reducing Turbine: Clearing for the transmission corridorwould change blrd nabltat from dense woodland to woodland edge. Somenesting habitat would be lost, but it does not appear to be a significantimpact. Prior to transmission line routing, tne area would be surveyedto assure bald eagle nesting would not be impacted and an adequate bufferzone would be estaDlisned near nesting activity.d. Fish:Hydroelectric: The impacts which would occur to the fisheryresources of All1son Creek are associated with changes in watertemperature and tne flow regime.Adult pink and cnum salmon spawn from July through Septemoer when thenatural high water temperature of Allison Creek is from 8 to 11 0 C.Spawning is directly related to stream temperature; salmon spawn earlierin the season in colder streams and later in the season in warmerstreams. Intertidal spawners also spawn later in the season. Because ofthe timing of spawning, intertidal and freshwater spawning salmon of thesame stream are of different genetic stock; interbreeding does notoccur. Although it is not known at this time, Allison Creek probably hastwo distinct runs of pink salmon in the odd years, the majority of theearly run enters and spawns in freshwater with a later run spawningalmost exclusively intertidally. Tne most plausible explanation for tnerelationship between time and stream temperatures is that they arecoordinated to provide optimulTI survival and the most advantageous timingfor emergence.The lake tap WOUld substantially cnange water temperatures at tne time ofspawning. The proposed project would draw water from the lake bottom ata temperature of approximately 4 0 C. Although there would be naturalflows occurring from the drainage basin Delow the outlet, (Appendix E,Taole 3) stream water temperatures would decrease. A temperature above4.5 0 C is critical for normal embryonic development. With temperaturesbelow 4.5 0 C, mortality increases, and spinal deformities occur. At 2 0C, complete mortality results. It appears during normal water years withnormal runoff into the stream below the lake outlet, water temperatureswith the proposed project would be above the critical level, however, lowwater years may cause temperatures oelow 4.5 0 C.EIS-13