Elwha Ecosystem Restoration

The Elwha Ecosystem Restoration Project is a 21st-century project of the U.S. National Park Service to remove two dams on the Elwha River on the Olympic Peninsula in Washington state, and restore the river to a natural state. It is the largest dam removal project in history and the second largest ecosystem restoration project in the history of the National Park Service, after the Restoration of the Everglades. The controversial project, costing about $351.4 million, has been contested and periodically blocked for decades. It has been supported by a major collaboration among the Lower Elwha Klallam Tribe, and federal and state agencies.

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.

Historically, the Elwha River was one of the few rivers in the contiguous United States that supported all of the anadromous salmonid species native to the Pacific Northwest. Ten stocks of anadromous salmon and trout species are known to have been present in the river before the dams were built: spring- and summer/fall-run Chinook salmon (Oncorhynchus tshawytscha), chum salmon (O. keta), coho salmon (O. kisutch), pink salmon (O. gorbuscha), sockeye salmon (O. nerka), summer- and winter-run steelhead trout (O. mykiss), bull trout (Salvelinus confluentus), and cutthroat trout (O. clarki clarki). The river was considered the most prolific fish producer on the Olympic Peninsula. It was particularly known for its very large Chinook salmon, weighing as much as 45 kilograms (99 lb). Prior to the construction of the two dams on the river in the early 20th century, an estimated 392,000 fish returned annually to spawn. By the late 20th century, the number had declined to less than 3,000.

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