Implications of Phosphorus TMDL on the Design of a Salmonid Acclimation Facility in Central Washington

The lower section of the Wenatchee River, a tributary of the Columbia River, is currently on Washington State's 303(d) list of impaired water bodies for temperature, pH and dissolved oxygen (DO) excursions. The Wenatchee River is among the sub-watersheds where supplementation of summer Chinook is being planned through, among various actions, acclimation of hatchery spawned fish at facilities operated in the Wenatchee River watershed. Salmonid acclimation involves an unavoidable introduction of nutrients in the effluent through fish feeding and fish wastes. An enhancement in the capacity of an ongoing fish acclimation program in the lower Wenatchee River is being proposed to maintain summer Chinook salmon stocks in the Wenatchee river watershed. This paper explores the design considerations necessary to enhance the fish capacity of the facility while simultaneously meeting the requirements of the Wenatchee River phosphorus TMDL allocations.