The Elwha River restoration back to its natural state was the largest dam removal project in U.S. history. It was completed on August 26, 2014.

Salmon spawning in a Washington stream

The largest dam removal project in United States history began September 2011. The controversial project, costing about $350 million, had been contested and periodically blocked for decades.

When the Dams Were Built, Salmon Were Blocked from Their Spawning Streams

The two problematic dams, Elwha Dam and Glines Canyon Dam, were constructed in 1910 and 1927.

Prior to blocking the river, an estimated 392,000 fish returned annually to spawn. This was one of the few rivers in the U.S. that supported all five species of salmon native to the Pacific Northwest. It was particularly known for its very large Chinook salmon that weighed as much as 100 pounds. Pink salmon were the most numerous with over 250,000 fish returning each year. By the 1980s that number fell to near zero.

Salmon is considered a keystone animal which provides a valuable food source for many animals, such as black bear, coyotes, gray wolves, bald eagles, raccoons, and dozens of others. Research in Olympic National Park has shown that more than 130 species benefit from salmon.

Drama From the Start

Elwha Dam Was Privately Built, Failed, and Repaired

Elwha Dam Public Domain

Thomas Aldwell bought up tracks of land around the Elwha River and built the dam to provide power to the upper Olympic Peninsula. However, the builder cut corners during construction and the lower part of the dam failed when the reservoir filled. The flood of water even took out a bridge downstream. The lower dam was repaired in 1913 with fill materials, but the dam never got an official federal license to operate.

Aldwell also balked at the Washington statute that required fish passages. After a court battle, a fish hatchery was built but closed after seven years because they failed to successfully rear fish.

Glines Dam Became Part of Olympic National Park

The Glines Canyon Dam and Lake Mills

Olympic National Park was not established until 1938, nine years after the Glines Dam was built. The park was expanded in 1940 to an area that included the Glines Dam and its reservoir, Lake Mills. The mission of national parks is to protect and preserve wild lands and wildlife, yet they inherited a manmade obstruction that harmed both the land and its natural occupants.

Dam Removals

The two dams were only producing a small amount of energy compared to other larger dams in Washington. Leaving one or both of the dams in place, even with modern fish passage systems, would not have resulted in a dramatic recovery of salmon because of water temperature and lack of gravel beds. Removal of both dams was considered the only viable option for full restoration of the river and spawning habitat.

The removal of the first of the two dams, the Elwha Dam, began in September 2011 and was completed ahead of schedule in March 2012.

Removal of the second dam, the Glines Canyon Dam, was completed on August 26, 2014.

Watch a Timelapse Video of the Removal of Both Dams

The Elwha River Today

The old Elwha Dam Site. David Krause

Today both dams are gone and the Lake Mills and Lake Aldwell reservoirs have drained. River sediment once trapped behind the dams is rebuilding habitats. Salmon and trout are naturally migrating past the former dam sites for the first time in over 100 years.

More information from the National Park Service: http://www.nps.gov/olym/learn/nature/elwha-ecosystem-restoration.htm

Source: https://en.wikipedia.org/wiki/Elwha_Ecosystem_Restoration