Fish then return to near surface pressure as they exit the draft tubes and enter the tailrace. As fish pass between the runner blades, they are exposed to a sudden drop in pressure. 6 However, all fish passing through turbines are exposed to various levels of pressure change. 1,2,3,4,5 Although blade strike is one of the most apparent sources of injury, the probability of strike from a large propeller-style turbine runner blade is relatively low, especially for small fish. How pressure affects fishįish passing through hydroturbines are exposed to various forces that may cause injury (e.g., shear forces, blade strike and pressure changes). A primary focus of the design and operational changes is minimizing the differential turbine pressures and resulting risk of barotraumas, which are injuries caused by a rapid decrease in pressure. In 2004, the USACE TSP team, with support from other regional engineers and fish biologists, began developing criteria and guidance toward the design of new turbines with potential to reduce direct and indirect sources of mortality to seaward-migrating juvenile salmon. Army Corps of Engineers (USACE) maintains and operates eight hydropower projects on the Lower Snake and Columbia rivers that form part of the Federal Columbia River Power System.Īs a component of a much larger effort to improve salmon passage through these hydropower projects, USACE implemented the Turbine Survival Program (TSP) to evaluate the turbine passage environment and to optimize the design and operation of large propeller-style turbines for safe fish passage. The configuration and operation of hydropower facilities on the mainstem Columbia and Lower Snake rivers is greatly influenced by the need to recover and sustain salmon and steelhead that are protected under the Endangered Species Act. This research is now being applied during a period when great emphasis is being placed on developing clean, renewable energy sources. Recent research conducted in this region has provided results that could lessen the impacts of hydropower production and make the technology more fish-friendly. Hydropower is a tremendous renewable energy resource in the Pacific Northwest that is managed with considerable cost and consideration for the safe migration of salmon. Installation of a new unit at 603-MW Ice Harbor is intended to provide field results to evaluate the success of this work.īy Richard S. Research into the effects of sudden pressure changes inside a turbine on fish is providing valuable insight to guide the design of fish-friendly turbines.
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