20% Of NW Rivers May Become Too Warm For Salmon, Steelhead - Seattle PI

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"If current warming trends continue unchecked, more than 20 percent of the Pacific Northwest's rivers could become too hot for salmon, steelhead and trout by 2040, according to a Northwest Wildlife Federation report.

The report, released yesterday, predicts that rising regional temperatures could disturb the delicate balance of seasonal stream flows -- making spring flows happen earlier, reducing summer flows to a trickle, or rendering winter flows so high that gravel beds used as nesting sites could get scoured away.

"Salmon in the region are struggling to survive amid dams, water diversions and development along river shorelines," said Paula Del Giudice, director of the group's Northwest Natural Resource Center in Seattle. "Global warming will add an enormous amount of pressure onto what's left of the region's prime cold-water fish habitat."

The report says climate change experts at the University of Washington consider it possible that average August temperatures could rise by 3 degrees Fahrenheit in the Northwest over the next 35 years. That could boost temperatures in some Columbia River Basin and coastal rivers in Washington and Oregon past 69.8 degrees, generally considered the high end of the temperature threshold for cold-water fish, the report said. Fish grow more slowly, become more susceptible to toxins, parasites and disease, and often die when river waters get too hot."

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http://seattlepi.nwsource.com/local/217366_warming24.html