Elwha Watershed Information Resource

The Elwha and Glines Canyon Dams were built on the Elwha River in the early 1900s and they have significantly changed the watershed.

The Elwha River watershed includes the 45-mile main river channel, over 100 miles of tributaries, and a 270-square-mile drainage area. The river originates in the Olympic Mountains and drops quickly through temperate forests before flowing into the Strait of Juan de Fuca (5 miles west of the city of Port Angeles, Washington).

The two dams essentially divided the Elwha River into three distinct sections:

• Lower river: below the Elwha Dam at mile 4.9
• Middle river: between the two dams
• Upper river: above the Glines Canyon Dam at river mile 13.6

Elwha Dam

Elwha Dam construction circa 1911. The use of explosives during construction dramatically altered the canyon. NPS/OLYM Archives-HAB HAER Report

In the early 1900s, the Olympic Power and Development Company (led by Thomas Aldwell) sought to harness the Elwha River for its power-generating capacity. In 1910, they began construction on the Elwha Dam--a project that would dramatically alter the Elwha watershed.

Construction on the 105-foot Elwha Dam was completed in 1914. The structure created the Lake Aldwell reservoir, which is 2.5 miles long and has a surface area of 267 square miles. Although state law at the time the dam was built required fish ladders, the project owner (Thomas Aldwell) circumvented the law by building a hatchery instead; the hatchery was short-lived, closing in 1922 after seven years (Wunderlich and others. 1994).

Glines Canyon Dam

In 1925, Northwestern Power and Light Company began construction on a second hydroelectric dam on the Elwha River, several miles upriver of the Elwha Dam. The 210-foot, single-arch Glines Canyon Dam was completed in 1927, and a large reservoir was created behind it. The Lake Mills reservoir has a surface area of 415 acres and contains 40,500 acre-feet of water. Like the Elwha Dam, this dam was built without fish passage facilities.

Positive effects of the dams

Glines Canyon Dam under construction in 1927. NPS/OLYM Archives

Together the dams generate over 28 megawatts of electricity. In the early 1900s, the dams provided a significant power source for burgeoning communities and industrial developments in Port Angeles (the nearest large city) and to cities as far as 60 miles away. However, the electricity demands of the communities near the dams are much greater today. Currently, the dams no longer play a significant role in meeting those demands; the dams provide just 40 percent of the power needs for one mill in Port Angeles (Wunderlich and others. 1994).

The dams also created two large reservoirs. This newly created habitat is beneficial to species (such as the trumpeter swan) that use lake habitat. People also use the man-made lakes for recreational purposes.

Negative effects of the dams

The dams had many negative effects on the watershed; some of the most notable affected the once-plentiful salmon runs by:

• Confining migrating salmon to the lowest 4.9 miles of river.
• Increasing the summer river water temperatures, which caused increases in disease, parasites, and fish mortality in the lower river.
• Decreasing the quality of available spawning habitat by restricting the natural transport of sediment and debris.

Historically, the salmon habitat included 70 miles of the river and its tributaries. It is estimated that the number of native salmon has dropped from pre-dam numbers of 380,000 to fewer than 3,000 in the 1990s (NPS 1996).

The declining salmon population has had a ripple effect on the watershed. Historically, salmon were an important source of food for wildlife (such as black bear) along much of the Elwha River. Today, wildlife above the Elwha Dam must rely on other sources of food or travel further down river to get salmon. Furthermore, watershed ecosystems that used to benefit from marine-derived nutrients from salmon carcasses no longer have access to those nutrients.

The reduction in fish coming upriver was a significant loss for the Lower Elwha Klallam Tribe as well--as both a source of food and income. Under the Treaty of Point No Point, the tribe reserved the right to fish at traditional sites on the Elwha River, a right that was upheld by the 1974 Boldt decision. However, the dams prevent the fish from traveling to these traditional sites.

Additionally, the dams flooded a large area of land (which was traditionally covered with native plants and home to many species of wildlife)to create the reservoirs. Currently, the dams' reservoirs cover approximately 684 acres of riparian and wetland habitat. Construction of the dams also left sacred and historical tribal sites underwater--such as the creation site of the Klallam people, which was flooded by the construction of the Elwha Dam (Wray 1997).

Timeline of the Elwha River dams

1910 - Construction begins on the Elwha Dam (at river mile 4.9)

1912 - Elwha Dam blows out during construction, flooding the area downstream where many Lower Elwha Klallam Tribe members lived

1914 - Elwha Dam is completed; Lake Aldwell reservoir is created

1922 - Fish hatchery (which was built as part of the Elwha Dam project) closes

1925 - Construction begins on the Glines Canyon Dam (at river mile 13.6)

1927 - Glines Canyon Dam is completed; Lake Mills reservoir is created

1938 - Congress establishes Olympic National Park, which includes Glines Canyon Dam within its boundaries

1974 - Boldt decision in U.S. v. Washington upholds tribal fishing rights

1975 - Lower Elwha Klallam Tribe's fish hatchery is built

1989 - Army Corps of Engineers builds dike on the Elwha River

1992 - Congress passes Elwha River Ecosystem and Fisheries Restoration Act

2000 - Federal government acquires Elwha River dams

2009 - Dam removal is scheduled to begin

Reference

NPS (National Park Service). 1996. Elwha River Ecosystem Restoration, Draft Environmental Impact Statement. National Park Service, Olympic National Park, 600 East Park Avenue, Port Angeles, Washington 98362.

Wray, J. 1997. "Ethnographic Overview and Assessment". Prepared for Olympic National Park.

Wunderlich, R. and others. August 1994. Restoration of the Elwha River Ecosystem. Fisheries. Volume 19. Pages 8, 11 to 19.