The Sandy River was about to begin flowing more freely down the slopes of Mount Hood for the first time in nearly a century with the start of demolition work at the Marmot Dam on today.
Portland General Electric was set to begin removal with explosive charges to weaken the concrete in the 47-foot-high dam.
Crews will have to use jackhammers and drills to break up the concrete and haul it away while a temporary dam diverts water during the demolition. But eventually, the concrete structure will be removed and the typical pattern of fall rainstorms will breach the temporary earthen dam and carry it downstream.
After demolition is complete, the Sandy will be a free-flowing river from its source among the glaciers of Mount Hood all the way to its mouth at the Columbia River for the first time in 95 years, utility officials said.
The name of the river dates all the way back to explorers Lewis and Clark, who named it for all the sand it washed down from ancient eruptions on the dormant volcano, the tallest peak in Oregon at 11,240 feet.
Marmot Dam was part of the Bull Run Hydroelectric Project that went on line in 1913 to provide power to the young city of Portland decades before construction technology advanced to the point that much more massive dams could be built along the Columbia River.
The Bull Run project provides enough electricity to power more than 10,000 homes. But PGE decided that operating the complex project was no longer economical and could be replaced more cheaply by wind generation.
The utility is spending $17 million to remove the Marmot Dam on the Sandy, along with the 16-foot Little Sandy Dam on the neighboring Little Sandy River. The removal work also will eliminate Rosyln Lake, lying between the two rivers, when demolition is completed in 2008.
The demolition project is expected to benefit threatened salmon and steelhead runs, and has been welcomed by environmental groups.
"The undammed Sandy River, flowing freely from Mount Hood to the Columbia, will be good for local businesses, clean water, and fish and wildlife," said Amy Kober of American Rivers. "The Sandy will show us that when a river is healthy, we all thrive."
PGE is donating about 1,500 acres for fish and wildlife habitat, and for public recreation. The area will be the centerpiece of a planned 9,000-acre natural resource and recreation area, officials say.
Environmental groups, state and federal agencies, and local governments and businesses were among the 23 groups that contributed to the dam removal plan.
The Bull Run project includes more than a mile and a half each of canals and tunnels that connect a three-mile wood box flume from Marmot Dam to the Little Sandy River just above Little Sandy Dam. Water from the Little Sandy River is diverted into Roslyn Lake, then returned to the Bull Run River after passing through a powerhouse.
Decommissioning hydroelectric projects has been rare nationally. The Federal Energy Regulatory Commission has authorized less than a couple of dozen out of more than 1,600 projects nationwide.
Most of the dams set for removal are small and date from the early 1900s, like the Marmot Dam.
PacifiCorp, another private utility based in Portland, has plans to remove dams from the Hood River, and from the White Salmon River in Washington state and the American Fork River in Utah. Pacific Gas and Electric, California's biggest utility, plans to remove a dam from a tributary of the Feather River in Northern California.
Other dams set for decommissioning include the Savage Rapids Dam along the Rogue River and two dams along the Elwha River in Washington state &
including what will be the nation's tallest dam to be decommissioned at 210-feet.
PGE begins Marmot Dam demolition