Work at dams and water spills boost salmon

FISHERIES — The rush of chinook salmon and steelhead running up the Columbia and Snake rivers this season is a product of a rush of water flowing down the river systems a few years ago.

A groupof federal agencies is pointing out that wild young Snake River steelhead migrated safely through federal dams on the Columbia and Snake rivers to the ocean last year at the second-highest rate on record. Recently released research indicates about 21 percent more steelhead passed safely through the dams in 2010 compared to the average since the late 1990s.

Young chinook and sockeye salmon also made it safely through the eight federal dams at higher-than-average rates, NOAA’s Northwest Fisheries Science Center found.

Researchers said the higher survival rates likely reflected two factors: the spill of water to help carry young fish past dams and recently installed surface passage systems that let fish slide through spillways near the water’s surface, where they naturally migrate.

Read on for more details  from the Federal Caucus of 10 agencies.

According to the Federal Caucus, spill and surface passage are both central components of the federal biological opinion that outlines measures to protect Columbia and Snake river fish listed under the federal Endangered Species Act. The biological opinion calls for spill at all eight federal dams on the Columbia and Snake rivers through the end of the active juvenile salmon migration in August.

The U.S. Army Corps of Engineers has also installed surface passage systems at all eight federal dams on the Columbia and Snake rivers in the last decade. Electric ratepayers fund most of the improvements through the Bonneville Power Administration.

NOAA research indicated that the surface passage systems, such as a new temporary spillway weir – also called a fish slide – at Little Goose Dam, helped speed young fish downstream by moving surface water more quickly through spillways. Faster travel downriver increases survival by reducing the exposure of young fish to predators and higher water temperatures, NOAA’s report said.

About 35 percent of fish were transported downstream by barge, fewer than in almost all previous years since 1995.

NOAA’s report also indicated that new aerial wires to reduce bird predation below John Day Dam and completion of a spill wall to guide fish away from predators at The Dalles Dam aids fish survival through the final three Columbia River dams — John Day, The Dalles and Bonneville. About 95 percent or more yearling salmon and steelhead passed safely through each of the three dams. 

 The Federal Caucus is a group of ten federal agencies operating in the Columbia River Basin that have natural resource responsibilities related to the ESA.  The agencies work together to better integrate, organize, and coordinate the federal fish recovery and water quality efforts in order to improve the Columbia River Basin aquatic ecosystem, and coordinate execution of federal trust and treaty responsibilities to Basin Native American tribes. The Caucus accomplishes these purposes consistent with each member agency’s missions and responsibilities.

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Rich Landers

Rich Landers’ Outdoors blog

Rich Landers writes and photographs stories for a wide range of outdoors coverage, including a Sunday feature section and a Thursday column. He also writes the Outdoors Blog.

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