Northbound and southbound I-5 each will be reduced to a single lane and northbound traffic will cross over to southbound lanes through 2 p.m. Friday, May 22, near Alger/Lake Samish Road (exit 240) to install a new fish passable structure beneath existing northbound lanes. Expect delays, especially during busier travel times, and consider alternate routes, such as SR 9 or SR 11/Chuckanut Drive.
The Alger/Lake Samish Road on-ramp to northbound I-5 will remain closed through Sunday, May 31.
Project overview
This project removes and replaces several outdated culverts under I-5 roads for the Unnamed Tributaries to Friday Creek, Lake Creek, Unnamed Tributary to Lake Creek and Chuckanut Creeks in Whatcom and Skagit counties.
WSDOT will replace outdated culverts with new fish-passable structures (also called culverts or bridges) for improved fish migration in the streams below as part of a statewide fish barrier correction program.
What to expect
Currently, this project is in the construction phase. Timelines are subject to change as construction plans are finalized.
The locations for culvert replacement are:
- Unnamed Tributaries to Friday Creek: milepost 241
- Lake Creek: milepost 245
- Unnamed Tributary to Lake Creek: milepost 246
- Chuckanut Creek: milepost 247
Construction of the Lake Creek crossing located just south of the North Lake Samish Exit (Exit 246) is mostly complete, but we still have some work to finish at this location.
Work on the Unnamed Tributary to Friday Creek crossing is expected to start in the spring of 2026. To install the new structures, I-5 traffic will be temporarily reduced to one lane in each direction at two separate times for brief periods. Northbound I-5 will close for 12 days in May. During this time both directions of traffic will use southbound I-5 (one lane in each direction). Following that closure, southbound I-5 will close for 15 days in July. During this time both directions of traffic will travel on northbound I-5 (one lane in each direction). Travelers should expect delays during this time. Additionally, in 2026 crews will construct a new crossing under Lake Samish Road) Interchange, which will require a 40-day road closure.
Construction on the Chuckanut Creek crossing is expected to begin in the summer of 2026. During this time, travelers will use temporary bypass roads for both directions of I-5 while new bridges are constructed. Old Samish Road will be closed while southbound I-5 traffic utilizes the county road. Once the I-5 bridges are completed, Old Samish Road will remain closed as a new bridge also will be constructed on that roadway for Chuckanut Creek. Restoration of the salmon stream channel habitat under the bridges is planned for the summer of 2027.
In 2027, work will begin at the North Lake Samish interchange (exit 246). During this phase, people traveling on northbound and southbound I-5 can expect nightly lane closures to construct temporary bypass roads. Travelers on I-5 will then use the temporary bypass roads through the summer while the Unnamed Tributary to Lake Creek crossing is under construction. A new culvert will be constructed across the existing lanes of traffic. Most of the work will take place without any ramp closures. A new culvert also will be built beneath the ramps.
WSDOT and contractor crews will coordinate with local agencies and emergency services to minimize delays and keep traffic moving through work zones.
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.
Replacing the outdated culverts with new ones will open up multiple miles of upstream habitat for salmon to spawn and grow. The new designs will include natural elements like logs and boulders to stabilize the channel, create habitat features, and restore the natural flow of the stream that was disrupted when the original culverts were installed under the highway.
The new culverts and natural features will make it easier for fish to move through the creeks by slowing the water and creating a more natural creek environment. A federal court injunction required the state to significantly increase its efforts to remove state-owned culverts that block salmon, bull trout, and steelhead habitats.