OLYMPIC NATIONAL PARK — Lake Mills behind Glines Canyon Dam will be lowered 18 feet starting today as part of the preparation for the removal of the dam and another on the Elwha River.
Bureau of Reclamation dam managers will lower the water level by about 1 ½ feet every day until it is about 18 feet lower than normal, Olympic National Park spokeswoman Barb Maynes said.
The water will be released by opening the dam’s spill gates, Maynes said.
The drawdown is expected to accelerate erosion along the new pilot channel dug in the delta at the top of the lake.
This drawdown is expected to last until Friday, Oct. 29. Fall and winter rains are expected to refill the reservoir.
“It is my understanding that the spill gates can be used until about this [18-foot] level,” Maynes said.
“We won’t lower it to such a level that the river will stop; we will only lower it to the point that the river can still flow.”
Lowering the lake will expose sediment, allowing the excavator operator to scoop a pilot channel through the blockage in preparation for the tear-down of the Glines Canyon and Elwha dams that will begin in September 2011.
The massive project is expected to be completed in March 2014.
The channel was dug in late September and early October.
The dam removals will open up 70 miles of the river and its tributaries.
As the water levels are drawn down, the boat ramp will not be usable, Maynes said.
“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,” Karen Gustin, Olympic National Park superintendent, said in a written statement.
“Lowering the reservoir levels will continue to give the river the head start it needs to erode the sediment.”
