Drivers heading to and from Seattle will see delays beginning next month, as the Washington State Department of Transportation begins construction of new culverts on both lanes of Interstate 5 between Arlington and Stanwood in Snohomish County.
In February, I-5 will be reduced to two lanes, and starting in May, drivers in both directions will be shifted onto a temporary two-lane bypass road for nine months. Construction on the interstate is supposed to wrap up in early 2026, before FIFA World Cup traffic starts in June.
In 2026, Old Highway 99 which runs parallel to I-5, will close for six months. Local and freight traffic will be diverted onto the interstate, or local drivers can use 4th Avenue NW. Project updates are available at WSDOT’s Secret Creek project page.
The $57.5 million project, funded by the Move Ahead Washington transportation package, is intended to open up fish passage in Secret Creek under the interstate and Old Highway 99. In 2023, WSDOT recorded a daily average of 90,000 vehicles traveling in both directions on I-5 in the vicinity of the project.
The U.S. District Court ruled in 2013 that WSDOT has a treaty-based duty to remove barriers in waterways under state roads that impede salmon migration by 2030. The estimated total cost of the decades-long fish passage program has doubled from $4 billion to almost $8 billion.
In the state Department of Fish and Wildlife’s fish passage inventory, Secret Creek is described as “great spawning and rearing habitat” with the potential to benefit chum, coho, steelhead, sea run cutthroat and resident trout. WSDOT expects the three new steel arch culverts to provide stream-habitat gain of nearly five miles, and serve as safe crossings for wildlife like deer, coyotes, bobcats and beavers.
The Secret Creek project will coincide with one a little closer to home — starting this spring, WSDOT will replace six old culverts that hinder fish passage in Friday Creek, Lake Creek, Chuckanut Creek and unnamed tributaries under I-5 near the Skagit-Whatcom county line. Construction will require nightly lane closures and then temporary bypasses through the summer.
Julia Tellman writes about civic issues and anything else that happens to cross her desk; contact her at juliatellman@cascadiadaily.com.
