Electrical Power for Valdez and the Copper River Basin-1981

1. PROJECT DESCRIPTION:Section 404(b)(1) EvaluationSouthcentral RailbeltValdez InterimThe proposed project consists of a lake tap at Allison Lake, power tunnel,above ground penstock, powerhouse, and a transmission line intertie withthe Solomon Gulch Substation. Approximately 5 cubic yards of riprap wouldbe placed in Allison Creek below the tailrace as an erosion protectionmeasure. Five cubic yards of riprap would also be placed below thetailrace to Port Valdez at the MHI~~ mark for erosion protection.2. AREA DESCRIPTION:a. Physical: The area impacted at Port Valdez would be approximately90 square fe8t of rock and cobble wi thin the intertidal area near themouth of Allison Creek. Five cubic yards of riprap would be placed inAllison Creck above the existing weir. The impacted area is wi thin thebanks of the stream on a rock and cobble area.b. Biological: The proposed disposal site in Port Valdez would be atthe MHI-tN level which supports little attached vegetation and minorpopulations of benthic organisms. The Allison Creek disposal site isabove any salmonid spawning or rearing and is in an area where thevelocity is high. The area contains typical algae and juvenileinvertebrate species associated with short, glacial fed, coastal streams.3. CONFORMITY WITH GUIDELINES:Evaluation Under 404(b)(1) Guidelines (40 CFR 230)a. Physical Effects: The direct ~hysical impact of this dischargeinvolves the elimination of 20 square yards of a water resource from thephysical, chemical, and biological systems. The work is exempt fromtesting since the material to be used does not represent a possible sourceof contamination to the surrounding aquatic ecosystem.b. Water Column Effects: Turbidity would increase during workoperations. Accordingl \f, light penetration would be decreased. Turbiditycaused by runoff at the project site would not be significant. Highnutrient concentrations or toxic materials would not be discharged intothe water column. The water column, as a whole, would not besignificantly impacted.