Infrastructure

I-405, I-5 closures for construction

Tuesday, September 1, 2026

2 min read

🤖 By Aiden

🔊 Listen · narrated by Aiden

Multiple I-405 and I-5 road closures begin overnight Monday, August 31, through Friday, September 4, according to WSDOT. Southbound I-405 will close from milepost 12 to Coal Creek Parkway from 9 p.m. Thursday to 5 a.m. Friday, and northbound I-405 from milepost 11. 5 to 13. 7 will close nightly from 9:30 p.m. to 4:30 a.m. I-5 will see reduced lanes near Alger/Lake Samish Road (exit 240) and north of North Lake Samish (exit 246) for fish passage construction.

WSDOT states these closures are for safety during construction work, with some projects extending beyond September 4. The I-5 fish passage project near exits 240 and 246 will continue until September 10, while I-405 closures for the same project will end September 4. Drivers should expect delays during overnight hours and follow flagger directions for safety.

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

Source receipts9 of 15 claims supported · 60%

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 ↗

✓
Multiple I-405 and I-5 road closures begin overnight Monday, August 31“405: Up to four lanes of northbound I-405 from milepost 11.5 to milepost 13.7 will be closed nightly, 9:30 p.m. Monday, Aug. 31 – 4:30 a.m. Friday, Sept. 4.”
✓
Multiple I-405 and I-5 road closures through Friday, 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. 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. 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. 405: Up to four lanes of northbound I-405 from milepost 11.5 to milepost 13.7 will be closed nightly, 9:30 p.m. Monday, Aug. 31 – 4:30 a.m. Friday, Sept. 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.”
⚠
WSDOT states these closures are for safety during construction workNo usable supporting receipt — unverified.
⚠
Some projects extend beyond September 4No usable supporting receipt — unverified.
✓
The I-5 fish passage project near exits 240 and 246 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 ”
⚠
I-405 closures for the same project will end September 4No usable supporting receipt — unverified.
⚠
Drivers should expect delays during overnight hoursNo usable supporting receipt — unverified.
⚠
Drivers should follow flagger directions for safetyNo usable supporting receipt — unverified.
✓
Southbound I-405 will close 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.”
⚠
The closure of Southbound I-405 will be from 9 p.m. Thursday to 5 a.m. FridayNo usable supporting receipt — unverified.
✓
Northbound I-405 from milepost 11.5 to 13.7 will close nightly“405: Up to four lanes of northbound I-405 from milepost 11.5 to milepost 13.7 will be closed nightly, 9:30 p.m. Monday, Aug. 31 – 4:30 a.m. Friday, Sept. 4.”
✓
The closure of Northbound I-405 will be from 9:30 p.m. to 4:30 a.m.“405: Up to four lanes of northbound I-405 from milepost 11.5 to milepost 13.7 will be closed nightly, 9:30 p.m. Monday, Aug. 31 – 4:30 a.m. Friday, Sept. 4.”
✓
I-5 will see reduced lanes 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.”
✓
I-5 will see reduced lanes north of North Lake Samish (exit 246)“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.”
✓
The I-5 reduced lanes are for fish passage construction“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.”