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Electrical Power for Valdez and the Copper River Basin-1981

Electrical Power for Valdez and the Copper River Basin-1981

Electrical Power for Valdez and the Copper River Basin-1981

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Waterfowl <strong>and</strong> water related birds found at <strong>the</strong> mouth of Allison Creek mayavoid tne immediate area during <strong>the</strong> construction phase with no long termadverse effects expected. The possible increase of freshwater into <strong>the</strong>bay may cause minor shoreline icing during winter months <strong>and</strong> coulddecrease <strong>the</strong> available habitat.Slignt changes in tne marine habitat would occur through <strong>the</strong> increase ofwinter freshwater <strong>and</strong> <strong>the</strong> placement of 5 cubic yards of riprap. Themarine habitat changes are considered minor.Pressure Reducing Turbine: Clearing <strong>for</strong> <strong>the</strong> transmission corridorwould change blrd nabltat from dense woodl<strong>and</strong> to woodl<strong>and</strong> 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 <strong>and</strong> an adequate bufferzone would be estaDlisned near nesting activity.d. Fish:Hydroelectric: The impacts which would occur to <strong>the</strong> fisheryresources of All1son Creek are associated with changes in watertemperature <strong>and</strong> tne flow regime.Adult pink <strong>and</strong> cnum salmon spawn from July through Septemoer when <strong>the</strong>natural high water temperature of Allison Creek is from 8 to 11 0 C.Spawning is directly related to stream temperature; salmon spawn earlierin <strong>the</strong> season in colder streams <strong>and</strong> later in <strong>the</strong> season in warmerstreams. Intertidal spawners also spawn later in <strong>the</strong> season. Because of<strong>the</strong> timing of spawning, intertidal <strong>and</strong> freshwater spawning salmon of <strong>the</strong>same 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 <strong>the</strong> odd years, <strong>the</strong> majority of <strong>the</strong>early run enters <strong>and</strong> spawns in freshwater with a later run spawningalmost exclusively intertidally. Tne most plausible explanation <strong>for</strong> tnerelationship between time <strong>and</strong> stream temperatures is that <strong>the</strong>y arecoordinated to provide optimulTI survival <strong>and</strong> <strong>the</strong> most advantageous timing<strong>for</strong> emergence.The lake tap WOUld substantially cnange water temperatures at tne time ofspawning. The proposed project would draw water from <strong>the</strong> lake bottom ata temperature of approximately 4 0 C. Although <strong>the</strong>re would be naturalflows occurring from <strong>the</strong> drainage basin Delow <strong>the</strong> outlet, (Appendix E,Taole 3) stream water temperatures would decrease. A temperature above4.5 0 C is critical <strong>for</strong> normal embryonic development. With temperaturesbelow 4.5 0 C, mortality increases, <strong>and</strong> spinal de<strong>for</strong>mities occur. At 2 0C, complete mortality results. It appears during normal water years withnormal runoff into <strong>the</strong> stream below <strong>the</strong> lake outlet, water temperatureswith <strong>the</strong> proposed project would be above <strong>the</strong> critical level, however, lowwater years may cause temperatures oelow 4.5 0 C.EIS-13

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