Agency continues work on Lower Granite Dam

LOWER GRANITE DAM - The federal government continues to seek fish passage improvements at lower Snake River dams, despite a recent court loss and the fifth legal setback in 20 years over its effort to save Snake River salmon and steelhead.

The U.S. Army Corps of Engineers recently wrapped up a $1 million project designed to cool water in the adult fish ladder at Lower Granite Dam. The agency is also in the middle of a $50 million redesign of a system that diverts juvenile salmon and steelhead away from turbine intakes at Lower Granite and flushes them a quarter-mile downstream before returning them to the river.

Both are examples that the agency's mission "continues marching forward," said Lt. Col. Timothy Vail, commander of the corps' Walla Walla District.

"It's not Groundhog Day," Vail said, responding to critics who likened the government's fifth court loss to the 1993 movie starring Bill Murray in which his character relives the same day over and over again. "We continue to make improvements every day."

Last month, U.S. District Judge Michael Simon struck down the corps' 2014 biological opinion, a massive document that attempts to mitigate harm that dams cause to salmon and steelhead through a series of "reasonably prudent alternatives." Those alternatives largely focus on improving habitat for salmon and steelhead in tributary spawning areas and the Columbia River estuary far from the dams. But they also include capital investment projects at the dams.

Simon gave the National Oceanic and Atmospheric Administration Fisheries Service, the corps and the Bonneville Power Administration, known collectively as the action agencies, two years to fix the biological opinion. But he left the 2014 version and the fish mitigation measures it calls for in place until the new one is finished.

One of those measures is the $50 million project that aims to improve the way juvenile fish are diverted through the dam as they migrate downstream to the Pacific Ocean. The system uses screens to keep as many fish as possible away from the electricity-generating turbines. Those fish are then fed into a pipe that goes through the dam and underground before reaching the juvenile fish facility, where they are either returned to the river or placed in barges to be shipped downstream. The latest project will replace the underground pipe with an elevated flume.

Fisheries biologist Ann Setter said the flume will cut the stress the fish must now endure while passing through the pressurized pipe.

"We believe the stress associated with passage through the facility will be reduced and that will be all-encompassing for all of the species," she said.

A second phase of the fish bypass system upgrade will extend the point at which juvenile fish are dumped back into the river by about 600 feet. The aim is to have the fish return to a portion of the river with a fast-moving current so they are not easy fodder for predatory fish and birds.

The fish ladder upgrade is designed to cool water in the stair-stepping canal adult fish use to climb over the dam. In recent years, high water temperatures at the top of the ladder have made fish like endangered sockeye salmon and early returning steelhead and fall chinook reluctant to leave the ladder. The longer they delay their migration upstream, the more susceptible they are to disease and other maladies.

The top of the ladder is fed with water from the surface of the Snake River, which can exceed 70 degrees in July and August. But the middle of the ladder and the lower portion are fed with colder water drawn from beneath the surface, where cold flows released from Dworshak Dam on the North Fork of the Clearwater River settle. When the water at the top of the ladder is several degrees warmer than the water at the bottom, it creates a "thermal barrier" that can stop migration.

Only 440 sockeye passed the dam last year, despite emergency efforts to pump cold water from a depth of 50 feet into the ladder. Over the past several months, contractors have installed a pair of chimneys that will divert cold water from as deep as 70 feet into the ladder. It will also spray a torrent of cold water at the upstream exit of the ladder to encourage fish to progress upstream.

"It also provides kind of a cool water refuge out in front of the fish ladder so the fish aren't coming 'wham' right from cool water into warm water," corps fisheries biologist Tim Wik said.

Vail said the action agencies are studying Simon's ruling and will respond appropriately. But he said the corps, its partner agencies and academic institutions will also continue to study and improve fish passage.

"We have been doing research since the construction of the dams, year after year," he said. " and we continue to make improvements so we can be as adaptive as possible."

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Barker may be contacted at ebarker@lmtribune.com or at (208) 848-2273. Follow him on Twitter @ezebarker.