SPOKANE — The government is making big improvements in fish passage facilities at Lower Granite Dam, hoping to increase the number of endangered salmon and steelhead that migrate through the Columbia-Snake river system, the U.S. Army Corps of Engineers said Thursday.
The dam is located on the Snake River west of Pullman.
“These fish passage improvements are part of the corps’ mission to protect salmon and other endangered fish species,” said Lt. Col. Timothy Vail, commander of the corps’ Walla Walla District. “We continue to upgrade our older dam infrastructure as planned and to respond to unusually hot weather conditions as we help fish migrate.”
One project is designed to deal with high water temperatures in the river in recent years, which can hurt migrating fish. Hot weather has raised summer water temperatures just below the dam to more than 68 degrees, the corps said.
The warmer temperatures form a “thermal barrier” to upstream migrating salmon and steelhead, stopping adult fish migrating upstream to their spawning grounds.
Last year, hundreds of thousands of adult salmon died because of warm temperatures in the reservoirs behind the Columbia and Snake River dams.
To help, the corps in February finished installing an adult fish ladder water cooling system at Lower Granite Dam.
The new cooling system involved construction of two “chimneys,” which are large vertical structures bolted to the face of the dam. The chimneys draw up cooler water from about 70 feet below the surface.
The corps is also constructing a Juvenile Bypass System upgrade, which will raise underground fish passage facilities to an elevated flume. This upgrade is expected to increase survival of juvenile fish migrating downstream.
The federal government has spent billions of dollars over decades on passage facilities to help salmon runs that were decimated by the construction of four dams on the Snake River in the middle of the last century.
Last month, a federal judge in Portland ruled that the massive habitat restoration effort by the U.S. government doesn’t do nearly enough to improve Northwest salmon runs. That ruling handed a major victory to conservationists, anglers and others who hope to someday see the four dams on the Snake River breached to make way for the fish.
U.S. District Judge Michael H. Simon found that for the past 20 years, the agencies have focused on trying to revive the basin’s 13 endangered and threatened salmon and steelhead runs by restoring habitat without compromising the generation of electricity. He said those efforts are failing.
The judge ordered the government to come up with a new plan by March 2018.
