Project overview
Reconnecting waterways where our roads act as barriers is a priority for the state. In western Washington, that means building hundreds of fish passable structures under state highways to create habitat essential for meeting fish recovery goals.
A culvert below State Route 509 west of Seattle-Tacoma International Airport is a barrier to fish migration through Miller Creek, a tributary of the Puget Sound. Beginning in late 2028, contractor crews working for WSDOT will begin installing a new fish passible structure that connects Miller Creek under SR 509. This project will replace the culvert and rebuild the stream to reopen habitat and restore salmon populations.
What to expect
WSDOT will select a qualified design-build contractor to complete the design of the fish passable structures for Miller Creek under SR 509. Although there is no funding for construction at this time, we are proceeding with the design phase of this project. Travelers should not expect to see construction in the area during this design phase. Highway closure needs will be determined by the type of structures and the construction method proposed by the contractor. It is expected that SR 509 will need to close for at least 30 days during fish passage construction. One lane of eastbound SR 509 will also need to close for at least 30 days during fish passage construction.
Work could begin as early as 2027. Although, the timing of culvert construction largely depends on the contractor, we anticipate construction on SR 509 could take up to two years.
Contractor crews will replace culverts below Des Moines Memorial Drive and State Route 509 with new fish passages.
Chum and coho salmon, sea-run cutthroat and resident trout use this stream for spawning and rearing their young. Restoring access for these species will create habitat for fish to lay eggs and for juveniles to grow stronger before migrating to the Puget Sound.
Miller Creek, which runs below SR 509, is only 33 percent passable for fish at this location. In 1998, seven concrete weirs, or fishways, were installed to help fish navigate the stream. Unfortunately, these fishways are too steep and prevent fish from being able to access spawning grounds.
The portion of the two existing six-foot diameter culverts under SR 509 will be filled in. In place of the old culverts, a larger fish passable structure will be built south under SR 509. Shifting the stream will introduce more daylight, shorten the stream crossings under the road, and improve habitat. Crews will also rebuild a portion of the channel so fish can more easily navigate the stream.
This work is part of our fish passage program. Replacing the existing culverts and rebuilding the stream channel will expand healthy fish habitat; an important step in restoring fish runs and increase populations. This benefits commercial seafood operations and 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.
