page_title: Elwha River
section_title: Dams
hierarchical_section_title: Elwha River / Dams
caption_attribution_description: English: Elwha Dam constructed 1913, slated for demolition 2012. Photo by Larry Ward, Lower Elwha Fisheries Office (2005).
context_page_description: The Elwha River is a 45-mile river on the Olympic Peninsula in the U.S. state of Washington. From its source at Elwha snowfinger in the Olympic Mountains, it flows generally north to the Strait of Juan de Fuca. Most of the river's course is within the Olympic National Park.
  The Elwha is one several rivers in the Pacific Northwest that hosts all five species of native Pacific salmon, plus four anadromous trout species. From 1911 to 2014, dams blocked fish passage on the lower Elwha River. Before the dams, 400,000 adult salmon returned yearly to spawn in 70 miles of river habitat. Prior to dam removal, fewer than 4,000 salmon returned each year in only 4.9 miles of habitat below the lower dam. The National Park Service removed the two dams as part of the $325 million Elwha Ecosystem Restoration Project. Dam removal work began in September 2011 and was completed in August 2014. The river has already carried sediment to its mouth, creating 70 acres of estuary habitat at the Strait of Juan de Fuca.
  The first documented use of the name Elwha River dates to Henry Kellett's 1846 map.
context_section_description: The river is the site of the largest dam removal project in history.  The Elwha Ecosystem Restoration project is the second largest ecosystem restoration project the National Park Service has attempted, after the Everglades. The Elwha River Ecosystem and Fisheries Restoration Act of 1992 was signed by the first President Bush after it was passed by Congress. The project was projected to cost $350 million. The act authorized the Secretary of the Interior to acquire and remove the two dams on the river and restore the ecosystem and native anadromous fisheries.
  The removal of the 108-foot (33 m) tall Elwha Dam and the 210-foot (64 m) tall Glines Canyon Dam began in September 2011. Two downstream water treatment facilities were completed in early 2010 to protect the water supply for the city of Port Angeles and the fish hatcheries from silt and sediment that would wash downstream once the dams were removed. In order to protect fish stocks below the dams during removal, the dams were taken out over a three-year process, pausing to ensure there would be no silt in the river while salmon spawned downstream.
  The Elwha Dam was completely dismantled in March 2012. Restoration of the area around the dam followed, including tens of thousands of native plants started in local greenhouses. The removal of the Glines Canyon Dam was completed in August 2014.
  Salmon will naturally recolonize the 70 miles (110 km) of habitat in Olympic National Park. The area once under the reservoirs is being revegetated to prevent erosion and speed up ecological restoration of the area. Because almost all of the Elwha's watershed is in a national park, the river should become relatively pristine, with few of the issues of agricultural runoff and water heating that affect other salmon river habitat in the Pacific Northwest. Model projections by the Park Service show that up to 392,000 fish will fill 70 miles of habitat, theoretically matching the "pre-dam peak".
  By late December 2012, about 10 percent of the estimated 25,000,000 cubic yards (19,000,000 m³) of sediment that had been caught behind the river's two dams had collected at the Elwha's mouth, forming sandbars. With the Elwha Dam removed, the sediment had been pushed downstream as heavy rainfall produced faster-moving flows in the free-running river. By November 2014, 30 percent of the stored sediment had been carried to the mouth of the river, creating 70 acres (28 hectares) of new estuary habitat for a wide variety of shellfish and other species.
caption: Elwha Dam with Lake Aldwell behind. The power house can be seen in the center.
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