Suquamish Tribe biologists have been bushwhacking throughout east Kitsap County looking for problematic culverts on salmon-bearing streams.

Since September 2022, biologists Hanna Brush, Theo Suver and Steve Todd have been visiting private, county and city properties to evaluate fish passage through culverts and other stream-crossing structures that have not been cataloged before, or where fish passage information needs to be updated.

Fish passage barriers are considered a critical stressor for salmon and steelhead that return to their native streams to spawn, Todd said, the tribe’s salmon recovery biologist.

“Fish passage is viewed as one of the limiting factors to healthy fish populations,” he said. “Coho especially are a big deal in Kitsap County because the Kitsap watersheds are basically made for coho, with the amount of wetlands, beaver activity, and multiple seasons and environments that coho live through before heading out to salt water.”

Steelhead are a federally listed species in Kitsap watersheds and use a variety of habitats year-round that can be blocked by culverts. Chum salmon are another important species to the tribe; they are challenged by some culverts because they are considered poor jumpers.

Using methods established by the Washington Department of Fish and Wildlife (WDFW), the tribe looks at the condition of the culvert and determines whether it is passable for fish.

Suquamish field biologists Theo Suver, top, and Hannah Brush collect data from a perched culvert in Poulsbo.

The criteria they look for include sloped pipes, significant drops from the culvert opening to the stream, the ratio of the channel width to the culvert width, and whether a portion of the culvert bottom is filled with fish-friendly sediment.

The width of the pipe is important because if it is too narrow, it can create a fire hose effect during high flows, scouring streambeds and making it difficult for fish to swim through, Todd said.

The tribe is focusing on streams within east Kitsap’s larger watersheds, including Blackjack, Chico, Curley, Clear and Dogfish. The tribe also is using a database that documents stream locations, lengths and whether they are fish-bearing or not.

The tribe is coordinating this work with other entities, including WDFW, local governments and private landowners who have granted access to identify where fish barrier assessments are most needed.

About 150 culverts are expected to be assessed through mid-2023. The tribe will then start compiling a list that prioritizes culverts most in need of repair based in part on the amount and quality of habitat that would be accessible to fish if a barrier is addressed. Todd said this database could help with obtaining funding for salmon habitat restoration projects.

Theo Suver, a Suquamish Tribe field biologist, at the end of culvert that is being inventoried for the tribe’s culvert assessment database. Photos and story: Tiffany Royal