OLYMPIC NATIONAL PARK — Several large boulders in the Elwha River channel just downstream of the Glines Canyon are being removed to ease fish passage.
The National Park Service has contracted Sealaska Constructors LLC to remove the boulders, said Barb Maynes, Olympic National Park spokeswoman.
Workers have detonated three controlled blasts to date, with at least one additional explosion still to come, she said, adding that the contract is included in the $325 million Elwha River Restoration project cost.
To accommodate the blasting schedule, Olympic Hot Springs Road is gated just above the Altair Campground until Oct. 16 after blasting has been completed.
Based on comparisons of historic and recent photos, and historic and recent water levels, geologists have determined that a large rockfall occurred sometime after Glines Canyon Dam was completed in 1927 and before dam removal began in 2011, Maynes said.
A significant portion of the canyon’s east wall broke off, sending large boulders into the river channel, which slowed and changed the river’s flow through the area.
As a result, since the completion of dam removal, sediment moving downstream from the former Lake Mills reservoir has accumulated above the rockfall, creating a barrier to upstream fish passage, Maynes said.
It has not completely blocked fish migration up river.
Chinook, steelhead and bull trout are known to have migrated above the Glines Canyon site, with some reaching as far upstream as Geyser Valley, Maynes said.
Removal of the obstructing boulders will further restore the river channel through the Glines Canyon, aiding the overall fish and ecosystem restoration of the Elwha River, she said.
The aim of the river restoration project was to free the Elwha River from two dams that had blocked fish passage for a century.
Elwha Dam was fully removed by March 2012, and the last of Glines Canyon Dam was destroyed in August 2014, opening up about 70 miles of river and tributary to once-legendary fish habitat.
Salmon were seen above the former Glines Canyon Dams for the first time in 102 years last September.
Olympic Hot Springs Road was closed just past Altair Campground for three years during removal of Glines Canyon Dam. That portion of the road had reopened in November.
