Oregon utility detonates charges to remove Marmot Dam

Oregon utility Portland General Electric set off explosives July 24 to weaken the concrete on 47-foot-tall Marmot Dam, signaling the start of the largest dam removal in Oregon history.

The detonation, followed by conventional demolition techniques, is part of a broader plan to decommission the 21-MW Bull Run hydroelectric project. (HNN 5/17/07)

Removal of Marmot Dam will make Oregon’s Sandy River free-flowing from Mt. Hood glaciers to its mouth at the Columbia River for the first time in 95 years, benefiting threatened salmon and steelhead, the utility said.

The event was observed from a viewing area about 1,000 feet from the blast zone. PGE Chief Executive Officer Peggy Fowler provided opening remarks to the event, attended by representatives of state and federal natural resource agencies, local governments and businesses, and environmental groups that worked on the dam removal plan.

A second dam in the Bull Run project, 16-foot-tall Little Sandy Dam, will be decommissioned in 2008. PGE and its ratepayers are to bear the entire $17 million cost of dam removal and decommissioning of the project, 40 miles east of Portland. Bull Run will generate electricity until work begins on Little Sandy Dam.

PGE said decommissioning Bull Run, including removal of the two dams, opens the way to improve wild salmon and steelhead runs that once were among the strongest on the Pacific Coast. The utility also is donating 1,500 acres of its Sandy River Basin land, which it described as the centerpiece of a planned 9,000-acre natural resource and recreation area.

PGE announced plans in 1999 to decommission the 1912-vintage project (No. 477) because the likely cost of environmental protection, mitigation, and enhancement measures associated with relicensing would make continued operation uneconomical. In 2002 it signed a dam removal agreement with the U.S. Fish &Wildlife Service and Oregon Department of Fish and Wildlife. The Federal Energy Regulatory Commission approved the plan in 2004.

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