Temperatures on the Stillaguamish River reached record highs while flows reached record lows this summer, which can be fatal for juvenile salmon migrating to sea and adult salmon returning to spawn.

Salmon need cool, shaded pools to rest and hide from predators, but many river systems in the region lack the woody material needed to create those pools. As co-managers of the salmon resource, the treaty tribes in Western Washington have worked in partnerships to install hundreds of engineered logjams throughout the region.

The Stillaguamish Tribe is in the second phase of a project to construct seven logjams in the North Fork Stillaguamish River and nearby side channels. The wood structures are being built on a former tree farm the tribe purchased about five years ago.

“It’s a really valuable piece of property in terms of conservation,” said Scott Rockwell, the tribe’s forest and fish biologist. “It’s unsuitable for other types of land use.”

This photo (the one with Scott) shows an engineered logjam on a stretch of the North Fork of the Stillaguamish River where the flat, featureless habitat had no shade. This summer, temperatures have exceeded 70 degrees in the Stillaguamish. Underneath this logjam is an 8-foot-deep pool of cool water that can mean the difference between life and death for salmon needing a place to rest and avoid predators.

Scott Rockwell, Stillaguamish forest and fish biologist, observes an 8-foot-deep pool underneath an engineered logjam on a stretch of the North Fork Stillaguamish River that had been without shade. When temperatures exceed 70 degrees in the Stillaguamish, this deep pool can mean the difference between life and death for salmon needing a place to rest and avoid predators.

The North Fork in particular is devoid of habitat complexity and vulnerable both to flooding as well as the current drought. Logjams mimic natural conditions, not only creating pools, but also improving overall complexity and recruiting cold groundwater.

“We started doing engineered logjams back in the 1990s, based on research done on the Hoh and Queets rivers within the National Park,” said Pat Stevenson, Stillaguamish environmental manager. “They studied and monitored what natural logjams looked like in a quasi-pristine environment. The structures we build are based on the natural setting.”

All five species of Pacific salmon spawn in the North Fork, as do steelhead and bull trout. The area was designated a priority for restoration in the 2005 Chinook Salmon Recovery Plan.