Heavy Lifting in a Salmon Stream: Alaska’s Tongass Forest Restores Habitat

Surveying the restoration of Twelvemile Creek on the Tongass National Forest, Alaska. Photo by Dustin Solberg, TNC

A Volvo 480 crawler excavator is a big yellow machine. Weighing in at well over 50 tons, it will move just about anything, such as a 17,000-pound log. Massive logs like these are key ingredients in restoring salmon streams but only if they’re put in the right place.

In all, a crew from a local contractor, Southeast Road Builders, carefully placed 325 logs in just the right spots in and along Alaska’s Twelvemile Creek – all in an effort to recreate the features that allow fish to thrive in a river.

“We’re asking them to use really big machines like fine-tuned instruments,” Brian Barr, a Forest Service hydrologist, told me as we waded the shallows to get a close-up view of a restored river.

This is the heart of the coastal temperate rainforest – a lush and green place known for giant trees, placid estuaries brimming with marine life and cascading salmon streams.

Pink salmon migrating upstream to spawn in Twelvemile Creek. Photo by Dustin Solberg, TNC

The Tongass National Forest is also home to more than 50 years of logging – much of it at a time when fish-friendly logging rules weren’t in effect. As a result, more than 90 percent of the valuable stream side forests were logged in this watershed. Tom Cady, a Tongass National Forest fish biologist who helped lead the project, put it this way:

“Twelvemile was probably one of the earlier areas of logging in the Tongass, in terms of industrial scale logging. And the logging that occurred here was performed under a different set of standards than what we have today with the national forest plan on the Tongass. So they were allowed, in those days, under an authorization by the Forest Service, to log clear up to the stream banks. And so that is the underlying role of this project, to really put back the conditions that were probably here before that occurred,” Cady said.

This work, led by the National Forest Foundation, the U.S. Forest Service, and The Nature Conservancy, is one example of how the Tongass National Forest is undergoing a transition toward restoring its streams and forests, and fostering healthy habitat for species such as fish and deer – keystone species for the ecosystem.

On Twelvemile Creek, this means restoring diverse and productive features – including pools, riffles, eddies and lots of big trees and root wads.
“Pools provide many habitat functions. They provide compartments for fish, especially for juveniles. If it’s nice and deep it provides nice cool water,” Barr says.
Over time, the diverse habitat has been disappearing, which means the time to intervene is now.

“We’re very fortunate at Twelvemile Creek. We still have a healthy salmon population in the creek,” Barr says. “We’re not working to bring back a decimated population. What we’re doing is we’re trying to preserve a population.”

And in Alaska, where abundant salmon runs are absolutely central to the economy, a way of life and a healthy ecosystem, this is worth a lot of heavy lifting.

The Nature Conservancy is the leading conservation organization working around the world to protect ecologically important lands and waters for nature and people.


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