SR 9 - Gribble Creek Fish Passage - Complete October 2018

In summer 2018 WSDOT contractor crews replaced a culvert that was a barrier to fish passage at Gribble Creek under State Route 9. Crews replaced the old round culverts with a larger culvert. Gribble Creek is located southeast of Mount Vernon in Skagit County. The creek passes through a culvert underneath SR 9 near between SR 538/East College Way and Big Lake.

Why did WSDOT replace the culvert underneath SR 9 at Gribble Creek?
As it was currently configured, the culvert was a barrier to fish. Water flows were sometimes too strong for younger and older fish to swim through because the culvert was too narrow. Building a wider culvert now allows the creek to flow more naturally under the highway and improve the fish habitat in the area. This fish passage project is one of more than 800 culverts that are mandated to be replaced. In 2013, the U.S. District Court for Western Washington ruled that the state must remove culverts that block fish passage under state roads.

What were the challenges of this project? 

  • Closing the highway: WSDOT crews closed the highway around-the-clock for five days this summer to safely and quickly complete this work, they were able to reopen the road ahead of schedule.
  • Keeping traffic moving: While WSDOT offered the contractor incentives to complete work at Gribble Creek early, roughly 5,500 vehicles a day were affected during construction.
  • Working near wetlands: Contractor crews needed to be careful working near and above the creek to keep any construction material and excessive sediment out of the creek and wetlands.

The End Result
The new culvert at Gribble Creek has helped restore the creek bed to a natural state and improve fish passage for salmon and steelhead, in compliance with the U.S. District Court ruling.

Needs & benefits

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


  • Fall 2017: Project will be advertised for competitive bidding.
  • Summer 2018: Estimated construction start date.
  • July 30 - SR 9 closure start date.
  • Fall 2018: Estimated construction completion date.
  • October 2018: Project complete.


Financial Data for PIN 100937H
Funding Source Amount ($ in thousands)

  • CWA - $3,418
  • Total - $3,418


Northwest Regino Communications