Biologists track fish recovery in tough conditions on Elwha River
From sonar to snorkels, biologists are using a range of tactics to keep track of fish recovery under way on the Elwha River.

The last of two fish-blocking dams are expected to be out as of mid-September, a major milestone in a $325 million recovery program for the river. From mountains to the sea, the Elwha valley is getting a reboot as the two hydropower dams, built without fish passage beginning in 1910, come down.

As the concrete tumbles, biologists from state and federal agencies and the Lower Elwha Klallam Tribe are working under difficult conditions to learn how recovery is progressing.

It’s not easy: The river is too big and wild to work in during the winter. And sediment — about 34 million cubic yards of it slowly being released from behind the dams since 2012 — makes the river about eight times cloudier than the glacial-floured Hoh River.

That’s tough on fish, and also on scientists trying to see what’s going on. It’s also rough on equipment: High sediment loads were one reason a weir used in the Elwha to trap and count fish has been pulled out of the river, said Rob Jones, chief of hatcheries and fisheries for the West Coast region of the National Oceanic and Atmospheric Administration (NOAA).

Pulling the weir prompted concern on the part of some wild-fish advocates, who filed a notice of intent to sue last week against the National Marine Fisheries Service, the tribe, and other federal agencies, contending the weir is central to monitoring recovery. It’s also necessary to control access of hatchery fish to the upper river, said Kurt Beardslee of Wild Fish Conservancy, one of several conservancy groups that filed the notice.

The effects of hatchery fish on wild fish are well-known, and fisheries-service managers acknowledged the possibility of harm to chinook and steelhead, listed for protection under the Endangered Species Act, in hatchery releases that are part of the recovery plan for the river. Hatchery fish reduce the fitness of wild fish if they interbreed, and they compete with wild fish for habitat and food. Hatchery fish also will prey on wild-origin fish.

The agency is predicting that those effects will be minimal, according to its analysis of the hatchery program for the river, with the benefit of bumping up fish populations in the near term outweighing the risks.

Right now the biggest concern is getting enough fish to survive at all, while the river is in its most tumultuous and turbid state in the first five years of dam removal, Jones said. “Our focus right now is to get through this initial phase.”

The biggest concern was over Chambers Creek-origin hatchery fish, which the tribe had planned to plant, but destroyed after the same advocacy groups went to court to stop that program. The last of the Chambers Creek fish came back last year, so one of the primary reasons for keeping the weir in place — intercepting those fish — is now moot, Jones said.

To track the course of recovery going forward, agencies are turning to other methods to count and identify fish.

One is sonar. Launched as a pilot program in 2008, two sonar devices today are deployed in the lower river to track and count steelhead and chinook in the river from about January through the end of the chinook migration in the early fall.

The benefit of sonar, said Keith Denton, a consultant to the Lower Elwha Klallam Tribe leading the monitoring effort, is that it can “see” through water too cloudy with sediment to detect passing fish by other means.

Last year, the devices helped biologists tally 4,200 chinook, the most in about 20 years coming back to the river.

This year, more than 700 chinook already have been counted in a migration that will continue into September. “There are hundreds, if not thousands of fish, everywhere we were, there were fish,” said Denton, of a monitoring trip this week.

Those returning adults went out to sea as juveniles before dam removal. They are coming home to a river transformed, with habitat opened 13 miles upstream to what’s left of Glines Canyon Dam.

That the fish would come into the river when it is so full of sediment is good news in an unprecedented program, in which no one knew at the outset what would happen as the dams started to come down.

Biologists are capturing adult chinook and steelhead and fitting them with radio tags, to track where they are going in the river and its tributaries. And they are inserting tagging chips in the bellies of juvenile salmon to detect them as they pass the mouths of two tributary creeks.

The goal is to see how the fish are utilizing the new habitat. By the time the dams are out, more than 70 miles of habitat will be opened that the fish had been shut out of for a century.

Elwha and Glines Canyon dams are the largest, at 110 and 210 feet tall respectively, ever taken down anywhere, and the amount of sediment behind Glines Canyon Dam alone, piled up, would overtop the Empire State Building about 2½ times, according to an analysis by Jonathan Warrick of the U.S. Geological Survey. Managers feared all the fish would die as the sediment was released, but that hasn’t happened.

Instead, fish are finding pockets of clear water, hugging the river banks, and finding other ways to survive.

“We are in a time when all of the things we are seeing are unprecedented,” Jones said. “We are out there looking for fish, to see how the river is responding to removal, and how the fish are responding so far. We are happy at the progress under way.”

On a recent visit to the Toutle River, still recovering from the cataclysmic eruption of Mount St. Helens in 1980, Jones was reminded of the Elwha. Both rivers are dynamic and changing every day.

John McMillan of NOAA fisheries snorkels the river looking for juvenile salmon and counts redds when the river is clear enough to see them.

In 2012, he counted 293 chinook redds, or salmon nests, above the former Elwha dam, during the first spawning season after the dam came down. In 2013, there were more than twice as many, with 592 redds counted.

And after an initial drop off, last year McMillan said he saw almost as many steelhead redds — 130 — as before dam removal. Indications are the fish are finding a way to survive and reproduce even in the muddy river, McMillan said. That was a surprise.

“The fish showed remarkable resilience in finding ways to survive,” McMillan said. “People probably underestimated their ability, me included. You just never know.”

Lynda V. Mapes: 206-464-2736 or lmapes@seattletimes.com