WHATCOM COUNTY, Wash. — The North Cascades Highway (SR20) remains closed between Colonial Creek Campground (near milepost 130) and Porcupine Creek (near milepost 156) due to significant winter storm damage and a spring rockslide during its seasonal winter closure. According to the Washington State Department of Transportation (WSDOT), damage includes multiple washouts, undermined roadway and unstable slopes across several miles. WSDOT said they expect to fully reopen the highway by Thursday, June 25, 2026.
This is an earlier date than previously estimated.
The North Cascades Highway remains closed to all vehicles, bicycles, hikers and campers between Colonial Creek Campground (near milepost 130) and Porcupine Creek (near milepost 156) until repairs are complete. SR 20 partially reopened from the east side on Thursday, April 30, but all vehicles must turnaround at Porcupine Creek.
– Washington State Department of Transportation
Emergency repair work began May 5, 2026, focusing on slope stabilization and debris removal at the site of a rockslide near milepost 131.
A second phase of emergency work began on May 13, 2026, focusing on rebuilding embankment, restoring more than 1,000 feet of undermined and collapsed roadway and shoulder and repairing damaged drainage, guardrail and concrete barrier along a 6-mile section between the Canyon Creek Trailhead and Granite Creek vicinities (mileposts 142-148).
Scene of work to stabilize a slope at site of a rockslide on N Cascades Hwy near Diablo Lake (May 19, 2026). Source: WSDOT 
Scene of work to repair 1 of several severely damaged sections of N Cascades Hwy (May 17, 2026). Source: WSDOT 
Scene of work to repair 1 of several severely damaged sections of N Cascades Hwy (May 17, 2026). Source: WSDOT
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