Between Seattle and Auburn, drivers cross over countless creeks and rivers. Each fall, salmon and steelhead swim a similar journey from Puget Sound, up the Duwamish River leading to the Green River, and into many tributary streams around Auburn. These creeks are vital habitat for salmon. Streams provide areas for salmon to reproduce, hatch, and grow, so young salmon are plentiful and healthy when they enter the ocean.
After leaving local waterways, salmon and steelhead spend several years in the Pacific Ocean before returning to King County waterways to repeat the cycle.
Just like people rely on roads to cross over creeks as they move throughout the region, salmon and steelhead rely on barrier-free creeks flowing under roads to reach vital upstream habitats.
This summer, King County Roads replaced a culvert carrying Mary Olson Creek under Green River Road near Kent. This project ensured that the road crossing the creek is up to current standards and restores fish passage to Mary Olson Creek. Prior to the project, a metal pipe or “culvert” carried the creek under the road. This culvert was old and in poor condition. It was also too small and steep for most fish to swim through and blocked salmon from migrating upstream of the road.
The new creek crossing uses a box culvert that is wide and deep enough to make sure that the creek under the road is “passable” for all species of fish, including salmon and steelhead. This work opens up more than 2,000 feet of stream habitat to full access by salmon and steelhead.
The county completed construction of the new culvert in late August and this fall, the county will plant some trees and shrubs along the creek channel to improve habitat conditions. The project, which cost about $900,000, provides a road crossing that benefits all, whether they are people travelling on the road or fish swimming in the creek.
The project is one of many being done by the King County Fish Passage Restoration Program with a goal of getting as many fish to the best habitat as soon as possible.
UPDATE: This video, taken Nov. 18, 2020, shows chum spawning inside the new Green River Road box culvert into Mary Olson Creek near Auburn. The use of the culvert by fish so soon after construction was completed, shows the success of the design and construction of the project by the King County Roads Division.
Video: Steve Conroy, King County Roads Division