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Middle Fork Side Channel Improvement
Project Contact: Steve Seymour, WDFW

The Nooksack basin is laced with side channels--old riverbeds or stream meanders that are a valuable element of fish habitat. One new channel was created during the 1995 Veterans Day flood, when the Middle Fork Nooksack abruptly changed course downstream of the Mosquito Lake Road bridge. The abandoned streambed became a new side channel fed by creeks and groundwater, which is now used by 5,000-10,000 pink salmon for spawning. Steelhead, coho, and a few chinook also spawn and rear in the channel.

However, the new side channel is a simple, uniform system of mostly glides and riffles, lacking in pools, channel “roughness,” and related traits that make up healthy, complex fish habitat. In addition, there are few standing trees big enough to become “large woody debris,” another element historically seen in healthy stream systems in western Washington. Large woody debris, either individual large trees or log jams, are one of a stream’s essential tools in forming pools and creating the complex habitats beneficial to both adult and juvenile salmon.

In the summer of 2003, the Washington Department of Fish and Wildlife (WDFW) and the Nooksack Salmon Enhancement Association began improvements to a 3500-foot segment of the channel. The project is meant to jump-start the stream’s ability to form complex fish habitat by adding large woody debris.

In the first phase of the project, 25 logs ranging from two to three feet in diameter were skidded in and placed in two- or three-log arrays along the channel. One hundred and forty smaller pieces of wood were flown in by helicopter and also added to the streambed. The work was funded by a grant from the state Salmon Recovery Funding Board and through a donation by Whatcom County Public Works. Washington Conservation Corps crews assisted with preparing the site and in building the arrays.

“The wood will give the water something to work against,” explains project manager Steve Seymour, a WDFW fish biologist. “Where there’s wood, the stream is forced to become narrower and is able to scour its bed, which helps to form pools. That will help to trap and sort gravel for spawning.” The wood also provides cover from predators for both adult and juvenile fish, and helps to keep the water cool.

After only a few months and a handful of rainstorms, the project is already beginning to show results. “The channel looks much different--it’s narrower and is starting to collect different sizes of gravel,” notes Seymour. “The smaller pieces of wood are bunching up in about three places along the stream, which is what we were expecting, while the larger pieces are mostly staying in place.”

Future improvements may include adding more wood and increasing the amount of flow in the channel. “Right now the channel is supplied by two spring-fed streams at about eight to ten cfs [cubic feet per second] apiece,” says Seymour. “It’s some of the nicest water I can think of in the county--cold, clean, and with a steady year-round flow. But there’s not enough water to entice early chinook to spawn in the channel.”

More improvements to the channel will be made over time. “We’ll work on this project over a two- to four-year span,” Seymour says. “We’ll try a little of one method, then sit back and see how well it works. Then we’ll go in the next year and use what we learned to make new improvements.”

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