Infrastructure

I-405, I-5, SR 4 closures begin this week

Sunday, August 30, 2026

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I-405 southbound lanes will close overnight Sept. 3-4 between mileposts 12 and 10. I-5 northbound and southbound will reduce to single lanes nightly from Aug. 31 through Sept. 4 near Alger/Lake Samish Road. SR 4 between 50th and 42nd Avenues will close one lane weekdays until Sept. 11 for gas line work.

WSDOT states the I-5 closures are for fish passage construction, with a project webpage for details. The I-405 southbound closure runs from 9 p.m. Thursday to 5 a.m. Friday. SR 4 work is scheduled 7:30 a.m. to 5 p.m. weekdays. Drivers should expect delays and follow flagger directions.

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

Source receipts8 of 9 claims supported · 89%

Legacy automated check: the original source text was not preserved. These earlier verdicts have not passed the current publication checks and may contain errors. Source: original document ↗

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I-405 southbound lanes will close overnight Sept. 3-4 between mileposts 12 and 10“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 northbound and southbound will reduce to single lanes nightly from Aug. 31 through Sept. 4 near Alger/Lake Samish Road“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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SR 4 between 50th and 42nd Avenues will close one lane weekdays until Sept. 11 for gas line 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.”
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WSDOT states the I-5 closures are 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. 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>.”
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WSDOT states the I-5 closures have a project webpage for details“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>.”
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The I-405 southbound closure runs from 9 p.m. Thursday to 5 a.m. Friday“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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SR 4 work is scheduled 7:30 a.m. to 5 p.m. weekdays“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.”
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Drivers should expect delaysNo usable supporting receipt — unverified.
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Drivers should follow flagger directions“Slow down, stay focused and watch for flaggers direction through the work zone.”