Corps can dredge Snake this winter
SEATTLE – Settling years of litigation, environmental groups on Thursday agreed to let the Army Corps of Engineers proceed with plans to dredge the Snake River this winter, as long as it does no more without conducting a long-term study about sediment build-up in the river.
The study should set the stage for a public discussion about breaching four dams on the Lower Snake, the environmental groups said.
“This is another opportunity to put before the public the true cost and impact of those dams,” said Bert Bowler, native fisheries director for Idaho Rivers United. “It’s a way of having the federal government come out and say, ‘Here are the costs and here are the benefits.’ “
In addition to providing hydroelectric power, the dams have created a navigable shipping channel for grain and other products to Lewiston, 465 miles from the Pacific. But the dams have largely destroyed Idaho’s salmon population, and river silt builds up behind them, creating a perennial problem for the corps and the threat of flooding in Lewiston and Clarkston.
The corps has not dredged the channel since 1999, when silt was removed from the Lower Monumental Dam navigational lock approach. Since then, the National Wildlife Federation and Idaho Rivers United have challenged any dredging, twice persuading U.S. District Judge Robert Lasnik in Seattle to block the corps’ plans as harmful to salmon.
The corps is authorized by Congress to maintain a shipping channel to the inland seaports of Lewiston and Clarkston that is 250 feet wide and 14 feet deep. Because of the silt buildup, the channel depth has decreased to 8.5 feet at the Port of Clarkston and 10.6 feet at the Port of Lewiston.
This spring, two grain barges became stuck in the ports and had to be pulled loose. Some shippers have been forced to reduce loads to compensate for the shallow depths, and others – most notably Potlatch Corp., the Port of Lewiston’s biggest customer – have increasingly been shipping by rail and road.
The dredging planned for this winter would remove 450,000 cubic yards of silt from the shipping channel near the confluence of the Snake and Clearwater rivers near the Idaho-Washington border, the approaches to navigational locks at Lower Granite and Lower Monumental dams, and port docking facilities. The corps would then redistribute the material in other river locations to improve salmon spawning habitat.
Dam-breaching advocates say the stress on fish forced to migrate from Idaho through the four Lower Snake dams – Ice Harbor, Lower Monumental, Little Goose and Lower Granite – in conjunction with global warming in the Pacific, are nudging native chinook and sockeye salmon toward extinction. This year, just six of the sockeye, which turn red as they swim upstream – returned to Redfish Lake in the central Idaho mountains.
Under the terms of the settlement, the corps would do no more dredging – except to avoid emergencies such as the loss of life, property or severe economic hardship – before completing a long-term sediment-management plan, to be finished by 2009.
The dams cannot be removed without congressional approval.