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Infrastructure

I-5, SR 20 closures planned for August-September 2026

Sunday, August 30, 2026

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WSDOT announced overnight and daily road closures on the Olympic Peninsula starting August 28 through September 11, 2026. The closures include two lanes of southbound I-405 from milepost 12 to 10 on September 3-4, and a single lane reduction on I-5 near Alger/Lake Samish Road from August 31 through September 4.

The I-5 closures near Alger/Lake Samish Road (exit 240) and north of North Lake Samish (exit 246) are for fish passage construction. SR 20 will alternate traffic with flaggers daily (except weekends) from Swin Slough Bridge to Laconner Whitney Road for Anacortes utilities work. SR 4 will close one lane both directions between 50th and 42nd Avenues weekdays until September 11 for gas main work.

Residents should expect delays during these closures. WSDOT notes that a detour will be in place for the I-405 northbound closure from August 28-31, and flaggers will direct traffic for SR 20 and SR 730 work. The I-5 fish passage project will continue until September 10, with nightly lane reductions from 8 p.m. to 5 a.m.

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

Source receipts9 of 11 claims supported · 82%

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WSDOT announced overnight and daily road closures on the Olympic Peninsula starting August 28 through September 11, 2026No usable supporting receipt — unverified.
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The closures include two lanes of southbound I-405 from milepost 12 to 10 on September 3-4“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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A single lane reduction on I-5 near Alger/Lake Samish Road from August 31 through September 4“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 I-5 closures near Alger/Lake Samish Road (exit 240) and north of North Lake Samish (exit 246) 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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SR 20 will alternate traffic with flaggers daily (except weekends) from Swin Slough Bridge to Laconner Whitney Road for Anacortes utilities work“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 close one lane both directions between 50th and 42nd Avenues weekdays until September 11 for gas main 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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Residents should expect delays during these closuresNo usable supporting receipt — unverified.
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WSDOT notes that a detour will be in place for the I-405 northbound closure from August 28-31“405: Up to three lanes of northbound I-405 will close from the Northeast 85th Street on-ramp to Northeast 100th Street from 11 p.m. Friday Aug. 28 to 5 a.m. Monday, Aug. 31. A signed detour will be in place.”
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Flaggers will direct traffic for SR 20 and SR 730 work“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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The I-5 fish passage project will continue until September 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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Nightly lane reductions from 8 p.m. to 5 a.m. on I-5 for the fish passage project“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.”