The Lower Elwha Klallam Tribe has begun preparing the lower Elwha River’s floodplain for the influx of sediment expected to come down the river after the Elwha and Glines Canyon dams are deconstructed starting in 2011.
“This work in the floodplain will help restore natural habitat forming processes in preparation for the expected release of the 20 million cubic feet of sediment trapped behind the dams,” said Mike McHenry, the tribe’s habitat program manager. “Our goal is to reconnect as much of the historic floodplain to the mainstem as possible. We are basically undoing historic channelization actions that have simplified the river.”
With $2 million in funding from the National Oceanic and Atmospheric Administration, the tribe will be constructing 20 engineered logjams, removing three manmade dikes, replacing two culverts with a larger culvert and a bridge, and planting native vegetation. This summer, the tribe filled in an unused 1,500-foot-long hatchery outfall ditch that was built in the middle of the floodplain in 1977. All this work will help improve the river’s function ahead of the dams’ removal.
Historic aerial photos show the lower river functioning as a natural floodplain before the hatchery outfall ditch was constructed. The ditch severely altered the flow of the river. The filling of the ditch, plus the removal of the dikes, manmade ditches and culverts, will allow water to flow throughout the floodplain, creating better habitat for salmon, where the fish can rest, feed and hide. The restoration work will also will help filter out the dam sediment as it flows into the Strait of Juan de Fuca.
The Elwha River is the largest tributary draining into the Strait of Juan de Fuca and historically, was one of the largest producers of salmon in the region. Puget Sound chinook and Puget Sound steelhead, both federally listed salmon species, reside in the Elwha River.
“People think that the current state of the mouth of the river is natural but there are manmade dikes throughout the lower river and estuary that constrict the flow,” said Jim Balsiger, Acting Assistant Administrator of NOAA’s National Marine Fisheries Service. “Historically, this river used to have several natural channels and drainages, but now has only one. We want to ensure that the river quickly returns to its natural state when the Elwha’s dams are removed.”
The 108-foot Elwha Dam and the 210-foot Glines Canyon dam are scheduled for removal beginning in 2011. The dams are owned by the federal government; the Olympic National Park is spearheading the removal effort. The total cost of the project is estimated at $308 million.
Funding for the project comes from a National Oceanic and Atmospheric Administration (NOAA) grant. Under the American Recovery and Reinvestment Act of 2009, NOAA distributed $167 million to 50 marine and coastal habitat restoration projects around the country. The Elwha Floodplain Restoration project was one of 50 projects out of 814 considered nationwide and received $2 million in funding.
For more information, contact Mike McHenry, Lower Elwha Klallam Tribe habitat program manager, at (360) 457-4012 ext. 14 or [email protected]; or Tiffany Royal, Northwest Indian Fisheries Commission information officer, at (360) 297-6546 or [email protected]