Elwha River Restoration: Former Aldwell Reservoir

This site overlooks the upper reach of the former Aldwell Reservoir, which extended 4.8 kilometers upstream from the Elwha Dam at river kilometer 7.9. After decades of lobbying led by the Lower Elwha Klallam Tribe, the passage of The Elwha River Ecosystem and Fisheries Restoration Act in 1992  enabled the removal of both hydroelectric dams on the river. The Elwha Dam was removed in 2011, followed by the Glines Canyon Dam (river km 21) in 2014. Once the majority of the 33 million tons of sediments held back by both dams  had been released and moved downstream or out to sea, the river could flow freely and begin to heal. 

 

Healing of a river system after over a century of disturbances is a complex process involving many interconnected components. Plants, animals, and people shape recovery dynamics in important ways such as nutrient transfer, ecosystem function and stewardship. The dewatering of the reservoir formed above the Lower Elwha Dam opened up 764 acres of land for the river to reclaim former anabranching channels, riparian plants communities to re-establish, and a diversity of habitats for a myriad of animal species to move through once again. 

 

Noxious weed control efforts since 2008 have played a major role in giving the native plants room to grow into the developing young forest you see today. In tandem with the natural recolonization of plants in the former reservoir, nearly 450,000 rooted plants, seeds and live stakes planted by people  have contributed to the regrowth of native plant communities, accelerating the restoration of ecosystem connectivity, habitat availability and access to culturally important foods and medicines. Wildlife camera trap monitoring  has already documented use of the revegetating reservoir by ten different terrestrial mammals, including Roosevelt elk and American black bears. Habitat restoration activities in the river reach affected by the former reservoir include the placement of twelve engineered logjams, which serve as habitat for benthic macroinvertebrates and juvenile fish, and facilitate the return of critical sediment transport procecess. 

 

Each Fall, Redd surveys are conducted throughout the river system to monitor how salmonids are returning to the river  and using the improved river habitats for spawning and rearing. In addition, SONAR imagery supports the enumeration of returning adults, while smolt traps are installed each Spring at four sites through the lower river to monitor juvenile outmigration. 

The removal of the Lower Elwha dam also uncovered culturally important places  to the Lower Elwha Klallam people that had been flooded or buried beneath the sediments for over a century; as salmon populations increase, Klallam people can continue healing spiritual connections  to the river interrupted by dams and moratoriums on fishing. 

 

To learn more about the Elwha dam removal history and river restoration, visit the Elwha (ʔéʔɬx̣w aʔ) River Ecosystem Recovery Resource Hub .