A proposal to remove two dams on the Elwha River is available for public review and comment through Dec. 7.
The Department of Interior, National Park Service, proposes to remove the Elwha and Glines Canyon Dams. This proposal requires permits from the U.S. Army Corps of Engineers, the Environmental Protection Agency, and the Washington Department of Ecology. These agencies issued a joint public notice Nov. 8, seeking public review and comment.
The purpose of the proposed project is to fully restore all runs of Elwha River native anadromous fish and restore the Elwha River ecosystem by removing the Elwha Dam which impounds Lake Aldwell and removing the Glines Canyon Dam which impounds Lake Mills. The proposal would also protect and restore treaty fishing rights for affected Indian tribes.
Work would take place in the Elwha River from the upper delta of Lake Mills at the Glines Canyon Dam in the Olympic National Park to the Strait of Juan de Fuca, near Port Angeles, in Clallam County, Washin
Since the dams were constructed, approximately 18 million cubic yards of materials (rock, gravel, sand and sediment) have been trapped behind the dams. Approximately 8 million cubic yards would be discharged into waters of the United States, mostly rock, sand and gravel, which would settle in the Elwha River flood plain and provide enhanced habitat for native fisheries. Approximately 5 million cubic yards would be discharged into the Strait of Juan de Fuca and would be mainly clays, silt and some sand. Of the remaining 9 million cubic yards of material in the upper Elwha watershed, it is estimated that approximately 4 million cubic yards may be eroded through natural processes and the remaining 5.4 million cubic yards would stabilize and provide a substrate for the re-vegetation process.
The Elwha Restoration Act has mandated the Department of the Interior maintain the existing level of flood protection for developments along the Elwha River, in addition to requiring that industrial and municipal water users be protected from the adverse water quality impacts of the proposed dam removal. Therefore, Interior has proposed mitigation measures to protect developments along the Elwha River. Restoration of natural sediment flow in the lower river would allow sediments to accumulate in areas that have eroded since the dams were built. This would result in an increase in elevation of the river’s water surface, ranging between one and four feet in some areas along the river, with an average increase of two feet.
Many residential and commercial sites are currently susceptible to flooding and could experience an increase in flooding if the dams are removed. Interior is proposing to raise and strengthen the Lower Elwha Federal Flood Control Levee, as well as strengthening the Place Road private levee on the western side of the Elwha River. In addition to flood protection, Interior will be undertaking measures to protect water intake structures affected by the project. The major impact would be a likely degradation of water quality during sediment erosion. Interior also proposes to construct a new water treatment plant for the Lower Elwha Klallam Tribe, a new Tribal hatchery, a new Elwha Surface Water Intake unit, the Elwha Water Treatment Plant, a new outfall for Nippon Paper. There are other proposed project elements that have also been incorporated into the overall project (dam removal) and must either be implemented or be nearly completed prior to the proposed removal of both dams. These measures would likely protect against adverse project impacts, as well as provide additional long term benefits to local water users.
The public notice is available on-line at:
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