As part of the Elwha River Watershed restoration, the two dams on the river are in the process of being removed and various restoration projects are being carried out to try to return the watershed to its pre dam condition. River restoration projects fall into two major categories: re-vegetation and engineered log jams.
Revegetation projects will help restore native plants to the areas around the dams. Currently, the dams and their reservoirs cover about 715 acres of land that was covered historically with native plants. Now that the dams are being removed and the reservoirs are being drained, 684 of those acres will be exposed and available for replanting.
In addition to blocking the passage of salmon upriver, the dams were blocking the downriver transport of trees, branches, and root wads. In healthy rivers and streams, large woody debris accumulates naturally and provides habitat for fish. The depletion of this debris from the lower Elwha River resulted in limited spawning and rearing habitat for salmon. In an effort to restore large woody debris (pre dam removal), engineers and biologists have constructed man-made versions of these debris collections called engineered log jams.
Learn more about the Elwha River restoration by clicking on the links below:
Revegetation: Restoration projects will focus on replanting the land behind the dams with native plants and preventing non-native plants from growing there. Ongoing research studies consider seedbanks, sediments, seed transport, invasive species, and methods for revegetation.
Engineered Log Jams: Since 1999, more than 33 engineered log jams have been installed in the Lower Elwha River to restore critical salmon habitat.
Goals and Objectives
This is a rare opportunity to fully restore an ecosystem where over 87% of the watershed lies within the boundaries of the Olympic National Park, and about 3% of the river is protected by the Tribe. As the dams remain in place this is a safety issue for everyone who lives below the dams. The dams were no longer efficient in producing power, and only provided power to the local mills.
The Federal government purchased the dams in 2001 circumventing legal action by the Tribe and environmental groups.
- Fully restore all Elwha River anadromous fish runs native to the Elwha River.
- Restore the Elwha River Ecosystem.
Interesting Facts about the River
- Mainstream is 45 miles long
- Drains 321 square miles of the Olympic Peninsula
- 4th largest river in the Olympic National Park by drainage size
- Largest percentage of watershed protected within Olympic National Park
- 30 miles of Tributary Streams accessible by salmon
- Elwha Dam was 105 ft. high, & constructed in 1910-12
- Glines Canyon Dam was 210 ft. high & constructed in 1927
- Total sediment accumulation 21 million cubic yards
- 2002 – 38,315 plants
- 2003 – 69,000 plants
- 2004 – 30,500 plants
- 2005 – 46,685 plants
- 2006 – 122,928 plants
- 2007 – 40,130 plants
- 2008 – 35,497 plants and 52,000 sq. ft. treated
- 2009 – 81,876 m2 gross area
- Replace undersized culvert with bridge (begin in Spring 2011)
- Remove unnecessary dikes (completed fall 2010)
- Fill in abandoned outfall channel. (completed summer 2010)
- Eradicate noxious weeds (completed fall 2010)
- Constructed 17engineered logjams in newly exposed reservoir
Tribal Mitigation Activities
Groundwater/wastewater: A report, by Ridolfi Engineering, in February 2002 concluded that changes in ground water levels responded to changes in river levels, confirming that there is a direct correlation between the river levels and ground water levels in the Valley area. The report also stated that the effects of a shallow depth to ground water could result in reducing, if not eliminating, the zone of separation between existing septic systems and the ground water table.
The outcome of Tribal community meetings during 2003 resulted in the decision to transport wastewater to the City of Port Angeles for Treatment. A wastewater agreement between the City of Port Angeles and Tribe was signed accepting to treat wastewater coming from the reservation in 2005. Final design was completed in 2010.
A construction contract has been awarded to L&N/MKB Joint Venture in late 2010. Construction Cost $8.28 million. Up to 109 residential homes and government facilities will be serviced by the wastewater system.