Infrastructure

I-405, I-5 Closures Continue Through Labor Day

Monday, August 31, 2026

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I-405 will close southbound lanes from milepost 12 to Coal Creek Parkway Southeast overnight Thursday, Sept. 3 to Friday, Sept. 4. I-5 will see single-lane reductions nightly near Alger/Lake Samish Road from Aug. 31 to Sept. 4 for fish passage construction. The closures are part of ongoing infrastructure projects. WSDOT states the I-5 fish passage work will continue until Sept. 10. For I-405, the southbound closure is scheduled for one night. Drivers should expect delays and follow detour signs. State Route 20 will have alternating traffic due to Anacortes utilities work beginning Aug. 21. SR 4 will have weekday lane closures between 50th and 42nd Avenues from Aug. 17 to Sept. 11 for gas main extension work.

📄 Source: WSDOT — Highway Construction & Closures — https://wsdot.wa.gov/travel/road-construction

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I-405 will close southbound lanes from milepost 12 to Coal Creek Parkway Southeast overnight Thursday, Sept. 3 to Friday, Sept. 4“405: Up to two lanes of southbound I-405 from milepost 12 to Coal Creek Parkway Southeast (milepost 10) will be closed overnight, 9 p.m. Thursday, Sept. 3 – 5 a.m. Friday, Sept. 4.”
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I-5 will see single-lane reductions nightly near Alger/Lake Samish Road from Aug. 31 to Sept. 4 for fish passage construction“005: The northbound and southbound I-5 will be reduced to a single lane from 8 p.m. to 5 a.m. nightly Monday, Aug. 31, through Friday morning, Sept. 4, near Alger/Lake Samish Road (exit 240) for fish passage construction.”
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The closures are part of ongoing infrastructure projectsNo usable supporting receipt — unverified.
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WSDOT states the I-5 fish passage work will continue until Sept. 10“005: The northbound and southbound I-5 will be reduced to a single lane from 8 p.m. to 5 a.m. nightly Monday, Aug. 31, through Friday morning, Sept. 4, near Alger/Lake Samish Road (exit 240) for fish passage construction. More information on the <a href="https://wsdot.wa.gov/construction-planning/search-projects/i-5-tributaries-friday-lake-chuckanut-creeks-fish-passage">project webpage</a>. Effective: Aug 14, 2026, 12:55 PM Expected end: Sep 10, 2026, 5:00 AM 005: The left lane of northbound I-5 will close from 8 p.m. to 5 a.m. nightly Sunday, Aug. 30, through Friday morning, Sept. 4, north of North Lake Samish (exit 246) for fish passage construction. More information on the <a href="https://wsdot.wa.gov/construction-planning/search-projects/i-5-tributaries-friday-lake-chuckanut-creeks-fish-passage">project webpage</a>. Effective: Aug 14, 2026, 12:49 PM Expected end: Sep 4, 2026, 5:00 AM ”
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For I-405, the southbound closure is scheduled for one nightNo usable supporting receipt — unverified.
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Drivers should expect delays and follow detour signsNo usable supporting receipt — unverified.
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State Route 20 will have alternating traffic due to Anacortes utilities work beginning Aug. 21“020: Daily (except Saturday, Sunday) beginning Aug. 21 until further notice: State Route 20 traffic will alternate with flaggers from the Swin Slough Bridge (milepost 50) to Laconner Whitney Road/Bay View Road (milepost 53) for city Anacortes utilities work.”
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SR 4 will have weekday lane closures between 50th and 42nd Avenues from Aug. 17 to Sept. 11 for gas main extension work“004: Monday, Aug. 17 through Friday, Sept. 11: A single lane in both directions of SR 4 between 50th Avenue (milepost 56.4) and 42nd Avenue (milepost 57.2) will be closed weekdays from 7:30 a.m. to 5 p.m., for buried gas main line extension work.”