Restoring logjams for threatened Nooksack salmon

Natural Resources, Uncategorized

Along the North Fork Nooksack River, gravel shores are left wanting – particularly while they bake in the sun during the summer months – for the shade, stability, and variety of habitats riverside trees can offer. Part of the problem in this particular stretch of the river is a lack of logjams accumulating naturally. Here, since large logjam structures were removed for river navigation and river-adjacent forests were cut down after European settlers arrived, the ecosystem has struggled to replenish that resource.

Without logjams in place, shorelines erode and eroded materials move downstream more rapidly. As those shorelines erode, trees that could have eventually grown large, fallen into the water, and become lodged in the river are washed away too soon – eventually leaving barren shorelines that no longer feed large wood into the river system at all.

The Tribe is working with partners to put the pieces back together in areas of the Nooksack River watershed that are most important for threatened Nooksack chinook salmon. One such area is located at the confluence of the North Fork of the river and Maple Creek. Whatcom Land Trust owns much of the land along lower Maple Creek, as well as along the left bank of the North Fork, and is a key partner in restoration in that area. This summer, the Tribe has had contractors sandbagging, digging, bundling logs, and building man-made logjams at strategic locations in this Maple Creek reach.

“It’s a lot harder to put logjams back in than it was to take them out,” the Tribe’s Watershed Restoration Coordinator Eric Stover said. Putting those logjams back in place is a critical piece, though, of restoring habitat for imperiled chinook salmon and other fish that spend the first and last days of their lives in the river and it’s tributary creeks.

TARGETING TREATY CHINOOK

The chinook of the North and Middle forks of the Nooksack River are a genetically unique population. That population is a subgroup of the broader Puget Sound chinook species protected under the Endangered Species Act because of low numbers of returning fish. Although the Tribe manages a limited subsistence fishery for personal consumption, it hasn’t directed commercial harvest on this salmon population since the late 1970s.

The primary goal of the work underway in the Maple Creek reach is to restore habitat that will in turn sustain and grow the natural-origin chinook population, eventually to levels that could again support sustainable harvests of those fish. The numbers of returning fish are currently a tiny fraction of historical estimates. An average of 152 adult fish returned per year between 2015 and 2019 compared to historical returns estimated in the 26,000-fish range.

According to the regional salmon recovery plan, these Nooksack chinook are considered critical to the overall recovery of the Puget Sound species. Restoring habitat in the North Fork, including in the Maple Creek reach, is among the highest priority areas for giving the Nooksack’s North and Middle forks population a boost. It’s listed as second only to the restoration of fish passage at the Middle Fork diversion dam – a project also recently in partnership with the Tribe.

In the North Fork, the primary factors limiting the growth of the chinook population are shoreline instability and a lack of protected side channel habitat. When adult fish come to this area and spawn, their fertilized eggs – tucked into gravel nests called redds – are left vulnerable to being washed downstream during high flows and flooding. Young fish emerging from those eggs are similarly vulnerable to strong streamflows because of the lack of slower-moving side channels to offer refuge. The restoration underway this year is designed to restore a key element – large log jams – that helps to stabilize the river and diversify fish habitat.

A BROADER EFFORT

Efforts to return natural ecosystem functions to the Maple Creek reach area to better support salmon began about 20 years ago, as the Whatcom Land Trust acquired 111 acres along the creek between 2003 and 2012. Work to restore plant life and texture to the landscape, as well as curves to the previously straightened creek, began in 2014. Positive results followed. Pink salmon and other salmon species returned to the restored creek to spawn, and the presence of eagles, coyotes, bears, cougars, and beaver dams was documented in the area. “It’s a really ecologically diverse and important area,” Stover said.

The Tribe’s work in the North Fork and along the riverbank is now complementing the Land Trust’s efforts along Maple Creek and is expected to result in a substantial improvement to salmon habitat in this reach of the watershed. The new logjams are also part of a growing network of structures being dispersed along the Nooksack River through projects like this one. The current construction – which will bring 17 logjams to about a half-mile segment of the river and its floodplain about a mile east of the town of Maple Falls – is the second phase of restoration in the area. Last year, the Tribe completed similar work that brought 22 logjams to a 0.3-mile span of the river just downstream of the current construction.

Stover said the logjams have proven to be sturdy additions to the river system, surviving even the flooding that swelled the river in November 2021. Now, the work currently underway in the Maple Creek reach marks the Tribe’s 22nd logjam-focused restoration project.

As part of Whatcom Water Week in September, the Tribe’s Natural Resources Department offered a tour of an earlier logjam restoration project, done along the Nooksack River tributary Hutchinson Creek. Engineered logjams the Tribe built there are successfully supporting salmon with sheltered habitat for spawning adults and migrating young.

At the Maple Creek Reach project site, logjams are being placed along the edges of the river as well as just beyond its current flow, creating areas where the river may reroute around the structures, disperse into side channels, and form pools. Much of the in-water site work had to be done during just a 30-day “fish window” from July 15 to August 15. Fish windows are when the Washington Department of Fish and Wildlife allows construction within rivers and streams based on the time of year that the fewest vulnerable fish are expected to be in those waters.

Even so, a team from the Tribe’s Natural Resources Department must ensure no fish are present before heavy machinery moves in and begins digging in the gravel and building logjams. That work involves isolating each worksite from the flow of the river, coaxing fish trapped in the isolated site into nets, and then releasing them into the river. The species and general age of each fish are documented as part of the process.

During one such exercise in August, the Natural Resources team caught and transferred coho salmon, steelhead or bull trout, and dace. The hope is that someday, perhaps soon, thriving chinook will be swimming alongside those species thanks to carefully placed logs anchored into the watershed.