County back at work rerouting mouth of Boise Creek; goal is to improve fish habitat

A Boise Creek restoration project that came to a sudden halt last summer is back on track. Crews are again at work building a new, wider channel for the final 800 feet of creek bed before it empties into the White River.

A Boise Creek restoration project that came to a sudden halt last summer is back on track.

Crews are again at work building a new, wider channel for the final 800 feet of creek bed before it empties into the White River.

King County spokesman Doug Williams said ground work could be completed this week, although water will probably not be diverted until fall, after crews have planted vegetation common to the area.

For a time, both the old and new channels will be used.

The goal of the project, Williams said, is to give very young salmon an alternative to fast-moving water, a place where they can rest, feed and avoid predators.

The existing creek is narrow and has steep walls, Williams said, which means salmon-spawning areas get washed away when the creek is flowing high and fast.

The project is just east of state Route 410, on the north side of Mud Mountain Dam Road, where Boise Creek had been rerouted decades ago. King County had received a $750,000 grant from the state’s Salmon Recovery Funding Board to redesign the mouth of the creek, aiming to make it more fish-friendly. The county had put money toward the project as well, pushing to total expected cost to nearly $800,000.

During the project’s planning stages, no one took into account the old railroad bridge that spanned the creek years ago. Last summer, after crews cleared trees, graded the land and began creating new stream beds, workers found old timbers coated with creosote, typically applied as a wood preservative. While effective, creosote also has associated health risks, forcing the county to halt construction.