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Steelhead Counts Drop at Snake and Col. River Dams by Eric Barker Lewiston Tribune, August 18, 2010

The daily counts of steelhead have dropped in recent days at Snake and Columbia River dams.

At Bonneville Dam on the Columbia River counts were nearing the 10,000 mark a week ago and have dropped to about 4,000 a day. At Lower Granite Dam on the Snake River, counts were running 500 to 1,000 fish a day. But they dropped to 266 on Monday and 164 on Tuesday. Other Snake and Columbia River dams have seen steelhead numbers drop from about 1,000 a day down to a few hundred.

The reduction in fish passing the dams is likely because of a combination of factors, according to Joe Hymer, a fisheries biologist for the Washington Department of Fish and Wildlife at Vancouver. He said at Bonneville Dam the A-run is winding down and the B-run fish are just starting to arrive.

Further up the Columbia and on the Snake River, the drop in counts is probably explained by rising water temperatures. The water at many of the dams and their reservoirs has risen into the low 70s. When that happens steelhead often look for places to cool off and pull into tributaries where the water is a few or several degrees cooler.

"They are starting to pull into the cooler water areas like Drano Lake, the White Salmon River and the Wind River," he said. "It's probably more related to warmer pool temperatures."

Hymer said fisheries managers slightly increased their prediction for the A-run. They now expect 375,000 to 400,000 to make it at least as far as the mouth of the Columbia. An earlier forecast called for 337,000. Fish managers are still expecting about 91,000 B-run steelhead.