The Army Corps of Engineers issued a permit today to the U.S. Department of the Interior, National Park Service, to remove the Elwha Dam and Glines Canyon Dam on the Elwha River and conduct associated work.
The National Park Service applied for a Department of the Army permit under Section 10 of the Rivers and Harbors Act and Section 404 of the Clean Water Act as required for the dam removal and work associated with removing both dams.
The purpose of the project is to fully restore all runs of Elwha River native anadromous fish and restore the Elwha River ecosystem by removing the Elwha and Glines Canyon dams, which impound lakes Aldwell and Mills respectively. The project will also protect and restore treaty fishing rights for affected Indian Tribes.
The permitted project area is on the Elwha River from the upper delta of Lake Mills at the Glines Canyon Dam in the Olympic National Park, downstream through the Lower Elwha Klallam Tribe Reservation, into to the Strait of Juan de Fuca, near Port Angeles, Wash.
"Returning the Elwha to a natural ecosystem outweighs the need that the dams once provided; generation of electricity and the resultant use of the reservoirs for boating and trout fishing," said Seattle District Commander Col. Michael McCormick in his permit decision. "I have determined that alternatives have been thoroughly explored and any unresolved conflicts have been addressed. The far-reaching long-term benefits of this project are readily apparent, and any associated impacts are manageable."
The National Park Service has designed flood and water quality mitigation measures to abate the impacts that would occur from the resulting increase in elevation of the river's water surface; which could range from between one and four feet in some areas along the river, with an average increase of two feet. Flood mitigation measures include modifying a private levee located at the western mouth of the Elwha River, in addition to modifying and lengthening the Federal levee on the eastern side of the river on the Lower Elwha Klallam Tribe Reservation. The National Park Service would also construct two water treatment plants, fish hatcheries, water supply pipelines, and other flood/water quality mitigation projects.
Deconstruction and drawdown of the dams would not occur until the mitigation measures are complete. Drawdown of the lakes behind the dams would be phased, with an initial reservoir drawdown from June through October during the first year of proposed removal. Natural discharge would allow erosion and natural redistribution of the sediments to restore fisheries habitat in the Elwha River. Approximately 75 percent of the 18 million cubic yards of sediment (rock, cobble, gravel, silt) are expected to be naturally eroded from both reservoirs.
The permit conditions require the National Park Service to restore all wetlands temporarily disturbed and/or impacted by the project activities within 13 months of project element completion. They will also be monitoring sediment discharge and conducting vegetation projects within the river corridor.
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