The South Davies Road culvert crossing for Stitch Creek provided a barrier to fish passage due to high velocities and flow depths in the 160 foot long, 3’ box culvert. Retrofitting the culvert using a baffle system was selected as the preferred remedy due to the high cost of replacement and good structural condition of the existing culvert.

The small (3’ x3’) culvert size would make manned entry for installation of WDFW standard baffles difficult. As an alternative, KPG and Snohomish County staff developed a system of pre-fabricated steel baffles that could be assembled outside of the actual culvert and pulled into place using a winch and chain. The chain and baffle assembly was secured to the upstream concrete apron using expansion bolts with no fixed points required within the culvert barrel. A trash rack was installed to reduce the risk large debris entering the culvert and collecting on the baffles.

KPG worked collaboratively with Snohomish County engineering staff, permit staff, and roads maintenance crews to obtain the necessary permits, fabricate the baffles and trash rack, and provide the final installation. A total of 14 baffles were installed by a single roads maintenance crew in less than one day of labor. Spawning Kokanee were observed upstream of the retrofitted culvert in the following months.