3-year fish passage replacement projects to impact I-5 traffic south of Bellingham

WHATCOM COUNTY, Wash. — Washington State Department of Transportation says a several projects over 3-years along a 6-mile section of I-5 south of Bellingham extending into Skagit County will begin 8pm on Wednesday, April 30, 2025.

A graphic map of fish passage construction on I-5 in Whatcom and Skagit Counties, orange dots show the locations of new fish passable structures (April 2025). Source: WSDOT

The projects to replace 17 culverts along a 6-mile stretch of I-5 in Skagit and Whatcom Counties will begin at 8pm on Wednesday, April 30, 2025.

WSDOT says motorists can expect the following traffic impacts through October 2025 as construction occurs at Lake Creek near the north end of Lake Samish.

Nighttime single-lane closures on I-5 from 8pm to 5am, starting Wednesday through early June
Temporary 2-lane bypass roads with reduced speed will be used for northbound and southbound I-5 traffic during the summer
Occasional nighttime rolling slowdowns, where traffic is briefly held or slowed to create a safe work zone ahead

Later in 2025, construction is expected to begin at unnamed tributaries to Friday Creek near Alger. That project schedule has not been finalized.

A 2013 federal court injunction required the state to significantly increase its efforts to remove state-owned culverts that block salmon, bull trout, and steelhead habitats by 2030.