VANCOUVER, Wash. — Nearly a century after it was built, the Condit Dam on the White Salmon River is about to be removed, reopening the Columbia River tributary for the passage of salmon and steelhead.
An Oregon utility said it has received federal regulatory approval and plans to begin demolishing the dam in late October, the Columbian newspaper reported.
PacifiCorp, based in Portland, Ore., originally planned to remove the dam in 2006 but demolition was repeatedly delayed. The estimated $32 million price tag for the project is nearly double the $17 million the utility expected to pay when PacifiCorp first announced plans to breach the dam in 1999.
On Monday, the company notified the Federal Energy Regulatory Commission that it had accepted the terms of its “surrender order,” a document that sets forth the conditions the company must meet to surrender its federal dam license.
“Decommissioning the hydroelectric project is now on a fast track,” PacifiCorp spokesman Tom Gauntt said.
The utility has also received a critical sediment management permit from the U.S. Army Corps of Engineers, one of the project’s last major hurdles, Gauntt said.
Completed in 1913 and standing 125 feet tall, Condit will be the second-highest dam ever removed in the United States. Glines Canyon Dam on Washington’s Elwha River, at 210 feet, will be the highest U.S. dam ever removed if it comes down on schedule in September.
The plans were welcomed by environmental groups and tribal leaders.
“This fall we will see two of the biggest river restoration projects in history, and they’re both in Washington,” said Amy Kober, spokeswoman for the conservation group American Rivers. “It’s an exciting river renaissance.”
In a statement, Virgil Lewis of the Yakama Nation Tribal Council called the announcement of the dam’s decommissioning “a momentous and long-awaited day.”
“This is an essential step in restoring the ecosystem’s resources and rebuilding the natural balance that supported the Yakama people and a significant tribal fishery for millennia,” Lewis said.
Prior to breaching, workers will dynamite a 12-foot by 18-foot tunnel through 80 feet of the dam’s 90-foot-thick base. On demolition day, they’ll blast through the final 10 feet. The impounded waters of Northwestern Lake behind the dam will flow through the tunnel at an initial rate of 10,000 cubic feet per second.
“It will be a controlled high-water event,” Gauntt said. “The flow that will be coming down will be more than what normally comes down, but it won’t cause any flooding.”
The 92-acre reservoir is expected to empty in about six hours while some 2.3 million cubic yards of sediment built up over nearly a century will be flushed downstream, killing virtually all life in the lower 3.3 miles of the river. The sediment will enter the Columbia River, which will carry it downstream all the way to Bonneville Dam.
Officials say the payoff will be that lower Columbia River chinook salmon will regain free and unrestrained access to 14 miles of habitat on the White Salmon and its tributaries, and mid-Columbia River steelhead will regain access to 33 miles of habitat in the watershed. The free-flowing river also is expected to protect critical bull trout habitat and benefit bears and other wildlife that feed on salmon.
The dam’s removal also will open a stretch of white water to rafters upstream.