SR 9 - Gribble Creek Fish Passage

Project news

  • WSDOT awarded this project to Interwest Construction, Inc.
  • Work will begin in July and will include a five day full closure of SR 9 in July or August.
  • Travelers should know about three other highway projects along SR 9 in Skagit County this summer.
  • Sign up for email updates about this project and other state roadwork in Skagit County.

In summer 2018 WSDOT contractor crews will replace a culvert that is a barrier to fish passage at Gribble Creek on State Route 9. The old round culvert will be replaced with a larger box 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 is WSDOT replacing the culvert underneath SR 9 at Gribble Creek?
As it’s currently configured, the culvert is a barrier to fish. Water flows are sometimes too strong for younger and older fish to swim through because the culvert is too narrow. 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 more than 800 culverts that are mandated to be replaced during the next 15 years. 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 are the challenges of this project? 

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

What travelers should expect
Crews will replace the small round culvert and a downstream arch culvert, which are a barrier to fish, with one 72 feet long, 19 feet wide and 15 feet high, to improve fish habitat.

  • Crews will need a five day, around-the-clock, closure of SR 9 to safely complete this work. That closure will happen in late July or early August. The detour around this closure will use SR 534, I-5 and SR 538.
  • In advance of that closure, travelers should expect a week of around-the-clock alternating traffic through this area.

The End Result
Building a new culvert at Gribble Creek will help 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.
  • Fall 2018: Estimated construction completion date.


Financial Data for PIN 100937H
Funding Source Amount ($ in thousands)
2003 Gas Tax (Nickel Funding) $0
2005 Gas Tax (TPA) $0
Pre-Existing Funds (PEF) $0
CWA $3,418
Total $3,418


Andrea E. Petrich
WSDOT communications

Shane Spahr 
WSDOT project engineer

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