PORT ANGELES — Adult chinook salmon, sockeye salmon, steelhead and bull trout were spotted in the upper Elwha River last month, the latest evidence of post-dam removal recolonization, fisheries biologists said.
Recent monitoring has revealed that the fish have passed upstream through the former Elwha and Glines Canyon dam sites, Olympic National Park officials said.
The observation is based on snorkel surveys that spotted fish but did not show the numbers that are swimming above the former dam sites.
“We are thrilled to see this latest confirmation of the success and value of dam removal,” acting park Superintendent Rachel Spector said in a Thursday news release.
“As restoration proceeds, the benefits continue to mount along the entire river and throughout its entire ecosystem.”
The National Park Service led a $325 million effort to restore the Elwha River to its natural state with the removal of the Elwha and Glines Canyon dams.
The fish-blocking dams were gone by 2014.
An early-August snorkel survey between Rica and Glines Canyons — upstream from both dam sites — revealed five adult chinook, one steelhead and 10 adult sockeye salmon, park officials said.
Biologists watched as two sockeye pairs dug nests, or redds, near the mouth of Boulder Creek in the former bed of Lake Mills, the reservoir created by the 210-foot Glines Canyon Dam.
Later in August, another snorkel survey between the Hayes River confluence and the Elkhorn Ranger Station revealed chinook, summer steelhead and bull trout, park officials said.
Biologists also use radio telemetry to track and monitor fish throughout the watershed. Fish are tagged in the lower Elwha River with a small radio transmitter, which emits radio signals detected by fixed antennas.
Using this method, scientists tracked an 18-inch bull trout from near the river mouth to a site 29 miles upstream near the Goldie River.
The signal also showed that the fish traveled 16 miles from Glines Canyon to the Goldie confluence in two weeks, officials said.
Contractors last fall demolished 14 large boulders that were part of a rockfall that occurred after constriction of the Glines Canyon Dam.
After dam removal, sediment and debris moved downstream and accumulated above the rockfall, creating a barrier to upstream fish passage.
“These observations indicate that last year’s rockfall demolition was effective in improving fish passage through Glines Canyon,” Spector said.
Later this month, biologists will use redd surveys and environmental DNA to assess chinook salmon recolonization and spawning in 40 miles of the river.
Biologists have also observed adult pink, coho and chum salmon and Pacific lamprey upstream of the former Elwha Dam site five miles from the river mouth, officials said.
Monitoring of the Elwha ecosystem is a joint effort of Olympic National Park, the Lower Elwha Klallam tribe, U.S. Fish and Wildlife Service, U.S. Geological Survey, National Oceanic and Atmospheric Administration Fisheries and the state Department of Fish and Wildlife.
For information on the ongoing restoration of the Elwha River, click on http://go.nps.gov/elwha.
Reporter Rob Ollikainen can be reached at 360-452-2345, ext. 56450, or at [email protected].