Preparations for Dam Removal Continue

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Date: October 19, 2010
Contact: Dave Reynolds, 360-565-2985

Preparations for next year's removal of the two Elwha River dams continue.

Earlier this month, contractors completed an erosion-enhancement project at the Lake Mills delta. Over a five-week period in September and October, workers removed trees, created a pilot channel through the middle of the delta and repositioned a logjam to direct the river into the new channel.

Beginning tomorrow, Bureau of Reclamation dam managers will begin lowering the water level in the Lake Mills reservoir to help accelerate erosion along the new pilot channel. The water level is currently about five feet lower than "full pool" and managers estimate that the level will drop approximately one-and-a-half feet each day until the level is 18 feet lower than normal. This is expected to occur on or around October 29.

Following the drawdown, fall rains will refill the reservoir. Given the unpredictable nature of the weather, no estimate is made for when this will occur.

Prior to the September-October erosion-enhancement project, alder trees had overgrown over much of the delta, stabilizing the sediments that make up the delta. Removing the trees and establishing the pilot channel gave the river a "head start" at eroding the delta. Lowering the reservoir will help maximize that ongoing erosion.

"Once dam removal begins, the river will carry large amounts of sediment downstream where it will restore fish habitat, shellfish beds and beaches along the Strait of Juan de Fuca," said Karen Gustin, Olympic National Park Superintendent. "Lowering the reservoir levels will continue to give the river the head start it needs to erode the sediment."

As reservoir levels drop during and after dam removal, the river will naturally erode and carry downstream the sediments that have accumulated in the reservoirs, replenishing downstream spawning beds and the estuary and beaches at the river's mouth.

The Lake Mills boat ramp will remain unusable during this period.

Last updated: February 28, 2015

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