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Beginning in February 2025, the Washington State Department of Transportation will begin construction of new fish passable structures on both northbound and southbound Interstate 5 at Secret Creek north of Arlington in Snohomish County. During construction, both northbound and southbound I-5 traffic will be shifted to a two-lane temporary bypass for 9 months with construction expected to be complete in 2026. In 2026, construction will move to Old Highway 99 which will be closed for six months during which time traffic will be detoured onto I-5.
Project overview
The Washington State Department of Transportation and its contractor will remove existing fish barriers under Interstate 5 and Old Highway 99 near Stanwood and replace them with three new steel arch structures to improve fish passage. The new culverts will be 68-feet wide and range from 50 to 70-feet long. Crews will also restore about 2,000 feet of creek channel, starting west of Old Highway 99, running through the I-5 median and extending to the east side of northbound I-5. This project is estimated to open up nearly 5 miles of habitat, benefiting salmon, steelhead, and other aquatic and wildlife species.
