Lamprey pass Oregon’s Soda Springs dam after 10 years of waiting


It felt like a normal Monday morning. Rich Grost pulled his truck to work and went to see what fish had swum past the Soda Springs Dam on Oregon’s North Umpqua River.

He thought he might see a giant 50 pound chinook salmon. What he saw was even better – after almost 10 years of waiting.

A Pacific lamprey propelled itself through the dam’s fish ladder.

Grost, an aquatic scientist with Pacific Power’s North Umpqua Hydroelectric Project, and an employee of the Oregon Department of Fish and Wildlife gave themselves a high five.

Grost said they had been waiting for what seemed like forever to see the lamprey swim past the Soda Springs Dam.

“It seemed like it was going to be an inevitable event, but it was like, when, when, when, when?” he said, about the excitement he felt that morning.

Pacific Power installed this fish ladder in 2012 with lamprey in mind. Lamprey need moist, rounded corners to climb fish ladders, unlike salmon.

However, while the salmon immediately started using the fish ladder, the lamprey did not cross the dam for 10 years.


Often fish ladders are designed with 90 degree angles and jumps for salmon. However, the lamprey uses its mouth, or oral discs, to suck up and jump down fish ladders and waterfalls, like Willamette Falls, said Kelly Coates, natural resources manager for the Cow Creek Band of the tribe of Umpqua Indians.

“They just suck their way to the falls. It’s kind of a unique move. It takes a lot of core strength,” Coates said, joking about how the lamprey moves upriver.

News of the first lamprey to cross the Soda Springs Dam quickly traveled among the large group of people and agencies who had worked to bring the lamprey to this point, about 180 miles inland from the Pacific Ocean.

Weeks later, a second lamprey sucked itself into the glassfish viewing area, possibly signaling that more lampreys could make the trip next year, said Sam Moyers, a biologist with the Department of Oregon Fish and Wildlife.

“It was quite late in the season when they came through the play-off,” Moyers said. “Usually further down the river they would have found their little hidden hole to spend the summer in.”

Moyers said he hopes more lampreys will cross the Soda Springs dam earlier in the season next year.

“It’s a matter of water temperature, and it’s a numbers game,” Moyers said.

The Pacific lamprey is a species at risk in the Northwest. Young lampreys spend at least five years in river sediments, feeding by filtration until they are able to migrate to the ocean.

When adult lampreys return inland to spawn, they do not always return to the exact location where they were born, as salmon do. Scientists believe that pheromones play a role in the direction of the lamprey’s head, which is one of the reasons Coates said she was thrilled to see the lamprey go over the Soda Springs Dam. Others might follow their pheromones.

Additionally, Coates said, lamprey, known as xtàan in Takelma, the language of the Cow Creek Band of the Umpqua Indian Tribe, is a culturally important first food for the tribe. Their fat-rich body is a good source of protein. Often people eat dried or smoked lamprey.

Additionally, indigenous peoples have traditionally used lamprey oils as hair and skin moisturizers. People also use lamprey as a traditional remedy, Coates said. For example, when her one-year-old daughter started teething, Coates said she fed her daughter dried lamprey.

“She slept better that night than she had in three nights,” Coat said. “So I can personally attest that lamprey is good medicine.”

The North Umpqua River is a common and habitual fishing ground for the Cow Creek Band of the Umpqua Tribe of Indians. Lamprey have not been harvested in this area for a very long time, she said. Harvesting lamprey is an eventual goal once the population is sustainable.

Beyond healing indigenous people, the return of the lamprey will help heal the ecosystem, Coates said. In addition to filtering food when young, lampreys provide food sources for other fish. The adult lamprey brings marine-derived nutrients to the streams in which the lamprey spawn and die.

The two lampreys that overran the Soda Springs Dam could signal a brighter future for lamprey in the Umpqua River system, Coates said.

“It helps restore balance, putting the system back on track to be healthy and functional,” she said.



It will be important to bring more lampreys into colder waters as climate change causes warmer waters, said Bob Nichols, Forest-Fish program manager for Umpqua National Forest. During the 2021 heat dome, huge numbers of lampreys died before reproducing in the South Umpqua River, Nichols said.

“Access to freshwater habitats is going to be pretty important going forward,” Nichols said.

Lamprey numbers in the Umpqua River system have been declining since the early 1970s.

However, more lampreys have appeared in the Umpqua River system recently, Moyers said. Nearly 1,400 lampreys appeared at Winchester Dam on the North Umpqua River, about 118 miles from the Pacific Ocean.

“That’s the highest number we’ve had since 1986,” Moyers said.

Those numbers likely contributed to a few lampreys moving further upstream into the North Umpqua system and into Soda Springs Dam, Moyers said.

Coates said the lamprey don’t have crossing barriers on the main stem of the South Umpqua River so they can approach the headwaters of the river. Now that the lamprey have passed the Soda Springs dam, they can also reach the headwaters of the North Umpqua River.

“It expands their range,” she said.

Barriers in the river, such as dams and culverts, are one of the biggest problems for lamprey, Coates said. The Pacific Lamprey Conservation Initiativeof which Coates is the tribal co-chairman, works with landowners to remove or modify walkway barriers to create rounded corners.

“Passage barriers are one of the main reasons we don’t see Pacific lamprey in more places,” Coates said.

US Fish and Wildlife Service

Adult Pacific lamprey.

Adult Pacific lamprey.

Dave Herasimtschuk/US Fish and Wildlife Service


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