Take a look below the mossy logs in Wolf Creek in Lincoln County – it’s teeming with juvenile coho salmon.
Fish and other aquatic life love downed woody debris and structure in streams. It provides food, shelter from predators, slows down water and creates conditions where fish are more likely to thrive. These coho salmon will grow a year in the stream and swim to the ocean to mature before eventually returning to freshwater as adults to spawn – but before they do, they need a safe place to grow up.
“Especially when there’s storms, there’s a lot of water, velocity and movement that can take all the gravel and sand and wash it down the stream,” said Zane Sandborg, a sales prep forester in ODF’s West Oregon District. “Fish need that gravel to spawn their eggs. We place the woody debris in and it slows down that water and captures those small rocks & gravel. It also creates torrents in the stream that will carve out pools, so when there’s less water in the stream in the summer there’s deeper pools for the fish to survive in throughout the summer.”
Nature often provides the woody structure these fish need. Where streams don’t have enough downed woody debris to create structure for fish, human intervention projects can bridge the gap. The fish pools shown in the video above were created with logs placed by the Oregon Department of Forestry as part of a stream restoration project in this area about 18 years ago. On this particular site, coho, steelhead, and cutthroat trout are native to the stream. But the creek banks are dominated by alder trees, which deteriorate faster than conifers like Douglas-fir and Western redcedar and aren’t as suitable for creating lasting conditions fish need to thrive. The successful project involved careful placement of conifer logs, which can last 70-80 years in the aquatic environment.
“When you have a stream riparian area with conifers, as they age and die and fall into the streams, storms will gather those logs at specific points in the stream and create these multi-log structures,” Sandborg said. “That’s what we’re trying to create here.”
Throughout Oregon state forestland, ODF teams up with the Oregon Department of Fish & Wildlife, watershed councils, and other partners to identify priority streams in need and take on projects that – over the long term – can result in healthier streams with higher fish populations.
With previous work showing success, ODF was back out on state forestland in Lincoln County for an additional phase of stream restoration. In close consultation with ODFW and ODF’s staff specialists, foresters identified areas in the creek where logs would likely gather if there was an adequate supply of wood.
For Sandborg, it’s satisfying to work on a project where prior signs of success are just a few minutes’ walk away.
“We know fish are here, they’re using these structures, and there’s a healthy population of fish who will return as adults and continue the cycle,” Sandborg said.