The removal of the dams on the Elwha River was put on hold last October while the National Park Service addressed issues associated with the water intake structure at the Elwha water facilities.
Those facilities, which includes the Elwha water treatment plant and Elwha surface water intake, are among several mitigation projects built to protect Elwha River water users from impacts associated with high sediment flows related to removing the Elwha and Glines Canyon dams.
The treatment plant is designed to deliver 53 million gallons of water daily during high sediment loads of up to 40,000 parts per million total suspended solids (ppm TSS).
Problems associated with the facility began last year, when material that was intended to be screened out by the water intake structure began moving further into the system, clogging pumps, filters and other equipment. Sediment, gravel, and large and small woody debris that was not intended to enter the treatment plant decreased the amount of water that could be delivered into the water treatment plant and increased the time and effort required to clean and maintain it. To date, maximum sediment loads have reached 10,000 ppm TSS.
Postponing downward notching of the dam also postpones release of the projected highest sediment levels into the river, allowing the NPS and contractors to complete corrections to the facilities.
The Elwha Dam is completely gone; removal of the remaining 50 feet of Glines Canyon Dam will resume in mid-September. The project is scheduled for completion before the contract ends in September 2014.
Click on the link below for more information about the Elwha River restoration project or go to the Elwha River restoration Facebook page.