Electrical Power for Valdez and the Copper River Basin-1981

Intertidal spawning, which is the majority of spawning activity, may alsobe affected by reduced temperatures, however, it is not known to whatextent. The t ida 1 range is approx imate 1y 18 feet ana depend i ng on whattidal level spawning occurs, the effects would vary. The most successfulspawning occurs above the -8 to -10-foot line from MHHW and at low tideswhen only freshwater would occur during early incubation. Whether theperioas of marine influence would compensate for the colder freshwater isunknown.Winter water temperatures of Allison CreeK would be warmer with tneproposed project than occurs naturally. Winter temperatures in the lakeat the depth of the tap are approximately 3.5 0C while the present wintertemperature of Allison Creek is near 00 C. The timing of emergence anddownstream migration of salmon fry depend on the temperature regimebecause the development rate depends on temperature. Warmer water fromthe proposed project would decrease incubation time, possibly by onemonth. If early emergence occurred, the likelihood of an adequate foodsource for the fry would be low. Intertidal incuoation and emergencewould also be accelerated, however not to the extent of instream spawning.As discussed earlier, spawning probably occurs in Allison Creek prior tointertidal spawning. The time-temperature coordination of spawning anddevelopment is a result of adaption, to assure that the norlllal time forseaward migration of the fry is the most opportune time for foodavai 1abil ity, and possibly saltwater temperatures.The proposed project would alter both temperatures at the time ofspawning activity and during incubation. Deviations from the existingtemperatures caused by project operations cannot but influence survival.Pressure Reaucing Turbine:project.No impacts to fish would occur with thise. IViarine: The additional freshwater in the winter months may havesome impact on the intertidal area. Much of the affected area receivesfreshwater during higher flows and marine productivity appears to beequal to the areas where high concentrations of freshwater do not occur.Whether part of the species' life history necessitates periods of nofreshwater influence is unknown: however, it appears that increasedwinter flows would have little effect.Mitigative measures require tne placement of approximately 5 cubic yardsof riprap below the tailrace for erosion protection. Approximately 10square yards of marine habitat at the MHHW mark would be covered.Recolonization may occur, but probably not to the extent of preconstructionproductivity.f. Rare and Endangered Species: There are no rare or endangeredspecies in the project area.3. Socio-EconomicTne construction pnase may employ as many as 100 persons. No constructioncamp is likely to be built, the employees would have to fino lodgingEIS-14