SR 531 - Edgecomb Creek - Fish Passage

Project news

  • Construction crews have installed the concrete culvert and guardrail and will continue to plant vegetation in the area.
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Edgecomb Creek currently weaves back and forth underneath SR 531 in Arlington using two culverts. Both are barriers to fish passage and need to be replaced. Rather than replacing two, WSDOT will realign Edgecomb Creek to the south of the highway so that the creek does not cross under SR 531. By installing a larger box culvert away from SR 531, stream flows will be improved for migratory fish. One of the two existing culverts will be plugged and the second left open for storm water drainage and backwater refuge for fish. The project will open up almost two miles of fish passage for steelhead trout, cutthroat trout, chum salmon and Coho salmon.

The work will require a weekend-long full closure of SR 531 at the project site. There will be a signed detour in place during the closure.

Why is WSDOT realigning Edgecomb Creek and installing a new culvert?
The existing culverts are a barrier to fish. Water flows are sometimes too shallow or too strong for younger and older fish to swim through. Building a wider culvert will allow the creek to flow more naturally under the highway and improve the fish habitat in the area. This fish passage project is one of about 1,000 culverts that are mandated to be replaced across the state. In 2013, the U.S. District Court for Western Washington ruled that the state must remove culverts that block fish passage under state roads.

The End Result
Installing a new culvert at Edgecomb Creek will help restore the creek bed to a natural state and improve fish passage for local migratory fish, in compliance with the U.S. District Court ruling.

Project Benefits

  • This project will improve fish passage and open up additional fish habitat.
  • The work will help WSDOT comply with the U.S. District Court ruling regarding fish passage.

What is the project timeline?

  • April 2017: Project is scheduled to go to competitive bidding.
  • June 2017: Construction is scheduled to begin.
  • Summer 2018: Construction is scheduled to be completed.


Financial Data for PIN 153175A
Funding Source Amount ($ in thousands)
2003 Gas Tax (Nickel Funding) $0
2005 Gas Tax (TPA) $0
Pre-Existing Funds (PEF) $3,002
CWA $0
Total $3,002


How can I get more information?

Marqise Allen
WSDOT communications
Phone: 206-440-4699