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Fish-Friendly Hydro Turbines on the Drawing Board by Liam Moriarty KPLU, March 29, 2010

SEATTLE - Hydro dams can cause big problems for migrating salmon. They block the fish from getting upstream to spawn. And going through the huge turbines on the way downstream can be deadly. Now, dam operators are spending millions to design a more fish-friendly turbine.

The idea of salmon going through hydroelectric turbines sounds like sending them through a blender. But the big blades turn relatively slowly and the fish don't get chopped up.

What does happen is that the turbulence and high pressure generated by the powerful turbines often injures or kills young fish finding their way out to the sea. Sean Nelson - with the Army Corps of Engineers - says the idea is to minimize the amount of turbulence that a fish experiences as it passes through.

The corps and the Bonneville Power Administration are paying a Pennsylvania firm to design and build a turbine with smoother interior passageways to cut down on salmon fatalities. An aging turbine at the Ice Harbor Dam on the Snake River would be the first to be replaced.