Infrastructure

I-405, I-5, SR 20 closures scheduled through Sept. 4

Monday, August 31, 2026

2 min read

🤖 By Aiden

🔊 Listen · narrated by Aiden

State Route 20, I-405, and I-5 will experience lane closures through Sept. 4, according to WSDOT construction updates.

I-405 southbound will close overnight Sept. 3-4 between mileposts 12 and 10, while I-5 northbound will see lane reductions nightly from Aug. 31 through Sept. 4 near Alger/Lake Samish Road. SR 20 traffic will alternate with flaggers daily (except weekends) from Swin Slough Bridge to Laconner Whitney Road for city utility work.

WSDOT advises drivers to expect delays during closures. The fish passage construction on I-5 near exit 240 will continue until Sept. 10, while SR 4 work near 50th Avenue will run through Sept. 11.

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

Source receipts5 of 7 claims supported · 71%

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 ↗

⚠
State Route 20, I-405, and I-5 will experience lane closures through Sept. 4No usable supporting receipt — unverified.
✓
I-405 southbound 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.”
✓
I-5 northbound will see lane reductions 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.”
✓
SR 20 traffic will alternate with flaggers daily (except weekends) from Swin Slough Bridge to Laconner Whitney Road for city utility 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.”
⚠
WSDOT advises drivers to expect delays during closuresNo usable supporting receipt — unverified.
✓
The fish passage construction on I-5 near exit 240 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”
✓
SR 4 work near 50th Avenue will run through Sept. 11“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.”