Project overview
Several blocked culverts below Interstate 90 and State Route 202 in east King County are a barrier to fish migration and will be replaced with new, larger culverts beginning in 2025. Contractor crews working for WSDOT will replace three culverts under I-90 in Preston and one culvert under SR 202 between Fall City and Redmond. Replacing these blocked passages will reopen miles of fish habitat and improve each area for other wildlife.
What to expect
Construction is expected to begin in 2028. The traffic management plan is still being developed, but travelers should expect to use a temporary bypass as work occurs on either direction of I-90. This traffic shift will keep vehicles moving while crews work on one direction of I-90 at a time. Lane closures may also be needed. A section of Upper Preston Road Southeast between 312th Way Southeast and Preston-Fall City Road will also close as part of the work.
Crews will need a full closure of SR 202 near East Main Street in order to install the new structure. WSDOT is still determining the closure duration and detour.
This project will focus on two culvert locations: I-90 near Preston and SR 202 between Fall City and Redmond.
Coho salmon, resident trout, Steelhead and Sea run cutthroat use these streams for spawning and rearing their young. Restoring access for these species will create habitat for fish to lay their eggs and for juveniles to grow stronger.
Soderman Creek, which runs below I-90 and Upper Preston Road, is fully blocked to fish. Crews will install three new structures in order to make the stream fish-passable: one structure below the eastbound lanes, one below the westbound lanes and another below Upper Preston Road just north of I-90. These new passages will improve access to more than half a mile of fish habitat.
The unnamed tributary to Patterson Creek that runs under SR 202 is partially blocked to fish migration. The existing stream channel flows down a slope before making two separate 90-degree turns through the culvert. Crews will install a new, larger structure just south of the current culvert, allowing the stream to flow more naturally. The new fish passage will improve access to as much as 2.2 miles of new fish habitat. The existing culvert will be left in place as an additional backwater refuge for migrating fish.
This work is part of our fish passage program. Replacing the existing culverts will remove barriers to fish migration and expand healthy fish habitat. Rebuilding habitat will help restore fish runs and increase populations. This benefits commercial seafood operations, recreational fishers, and provides more food for a declining orca population. Additionally, replacing these fish barriers helps us meet our obligation to remove barriers under the 2013 U.S. District Court injunction.
