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Field Notes

Covering the natural wonders of the Pacific Northwest

March 16, 2012 at 3:02 PM

Elwha River back in its natural channel; first time in a century

At 7:30 Friday morning, contractors started shifting the Elwha River back into its natural channel. Within four to five days, the river will be fully back in its native channel — for the first time in a century.

Within four to five weeks, the final draw down of Lake Aldwell, the reservoir behind Elwha Dam, will also be complete — and the dam, and its reservoir, will be history.

Contractors began taking down two dams on the Elwha River last September to restore the river and watershed.The restoration project is way ahead of schedule.

The two dams generated hydropower for the industrialization of the Olympic Peninsula, particularly the development of lumber, pulp, and paper mills. But the dams were built without fish passage.

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The Elwha River, back in its natural channel for the first time in a century. Photo courtesy of National Park Service

With Elwha Dam completely gone as soon as April, fall chinook salmon — the fabled Elwha Tyee — could make it all the way back to Glines Canyon Dam this migration season for the first time since the river was impounded beginning in 1910.

The big chinook usually start entering the river in July and have been seen holding in a pool at the foot of Elwha dam, blocked in their migration, ever since the river was dammed. But this year, the fish will regain an additional eight miles of mainstem spawning ground. Work on dam removal will be stopped while the fish migration is underway.

When both dams are out. they will regain the entire river, some 70 miles of spawning habitat, 83 percent of it permanently protected within Olympic National Park and never developed.

Barb Maynes, spokeswoman for Olympic National Park, said Glines Canyon Dam could be down ahead of schedule, too. Once forecast to take up to three years, nobody thinks the dam removal project will take that long anymore. Glines may be gone as soon as June of 2013.

Meanwhile, revegetation work on the deltas behind the dams is over for the year, with some 30,000 native plants planted.

The replanting is an effort to get ahead of the weeds that could otherwise take over the extensive sediment deltas exposed as the reservoirs drain.

Monitoring of out-migrating smolts, or baby salmon by the Lower Elwha Klallam Tribe so far shows that the young fish headed to salt water this season have been unaffected by elevated levels of sediment in the river, said Mike McHenry, habitat biologist for the tribe. Chinook, chum, and pink salmon found in the smolt trap maintained in the lower river by the tribe all look normal, McHenry said.

“So far, so good,” he said. “But the real impacts are yet to come.”

As reservoir levels continue to drop, and the Elwha works its bed to which it was just returned, sediment levels are expected to increase, McHenry said.

For more on the restoration project, history of the dams, revegetation and sediment management, see our special project in the Seattle Times.

To watch dam removal as it happens, take a look at the National Park Service web cams.

The photos show you, in part, what it takes to take down a dam:

Top photo: Used bit, dull from chiseling down Elwha and Glines Canyon Dam. Courtesy, National Park Service

Bottom photo: New bit. Ready for action. Courtesy, National Park Service

dull bit from hydraulic hammer.jpg

new bit.jpg

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