Infrastructure

I-405, SR 527, I-5 closures in Skagit Valley

Monday, August 31, 2026

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Multiple highway closures and lane reductions will affect Skagit Valley commuters starting Monday, Aug. 31.

I-405 will see overnight closures of up to four lanes southbound from milepost 13.4 to 11.4 and up to two lanes southbound from milepost 12 to Coal Creek Parkway from 9 p.m. Thursday, Sept. 3, to 5 a.m. Friday, Sept. 4. SR 527 will have a right lane closure overnight at the I-405 ramps from 11:59 p.m. Monday, Aug. 31, to 5 a.m. Tuesday, Sept. 1. I-5 will have single-lane reductions nightly near Alger/Lake Samish Road (exit 240) for fish passage construction, beginning Aug. 31 and continuing through Sept. 10.

WSDOT notes the closures are for utility work, fish passage construction, and gas main extension. Drivers should expect delays and follow flagger directions. The I-5 fish passage project is ongoing through Sept. 10, and SR 4 will have lane closures weekdays until Sept. 11 for gas line work.

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

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Multiple highway closures and lane reductions will affect Skagit Valley commuters starting Monday, Aug. 31.“405: Up to four lanes of southbound I-405 from milepost 13.4 to milepost 11.4 will be closed nightly, 8 p.m. Monday, Aug. 31 – 5 a.m. Thursday, Sept. 3.”
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I-405 will see overnight closures of up to four lanes southbound from milepost 13.4 to 11.4“405: Up to four lanes of southbound I-405 from milepost 13.4 to milepost 11.4 will be closed nightly, 8 p.m. Monday, Aug. 31 – 5 a.m. Thursday, Sept. 3.”
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I-405 will see overnight closures of up to two lanes southbound from milepost 12 to Coal Creek Parkway“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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The closures on I-405 will occur from 9 p.m. Thursday, Sept. 3, to 5 a.m. 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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SR 527 will have a right lane closure overnight at the I-405 ramps“527: The right lane of northbound SR 527 at the I-405 ramps (milepost 2.6 to milepost 2.95) will be closed overnight from 11:59 p.m. Monday, Aug. 31 to 5 a.m. Tuesday, Sept. 1.”
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The right lane closure on SR 527 will occur from 11:59 p.m. Monday, Aug. 31, to 5 a.m. Tuesday, Sept. 1“527: The right lane of northbound SR 527 at the I-405 ramps (milepost 2.6 to milepost 2.95) will be closed overnight from 11:59 p.m. Monday, Aug. 31 to 5 a.m. Tuesday, Sept. 1.”
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I-5 will have single-lane reductions nightly near Alger/Lake Samish Road (exit 240)“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 single-lane reductions on I-5 will begin Aug. 31“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 single-lane reductions on I-5 will continue through Sept. 10No usable supporting receipt — unverified.
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The I-5 fish passage project is ongoing through 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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WSDOT notes the closures are for utility work, fish passage construction, and gas main extension“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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Drivers should expect delays and follow flagger directionsNo usable supporting receipt — unverified.
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SR 4 will have lane closures 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.”