SR 20/North Cascades Highway fully reopened after repairs were completed on Sunday, June 14.
Project overview
The North Cascades Highway fully reopened Sunday, June 14.
Beginning May 5, 2026, work began on the first of two emergency repair contracts to reopen SR 20 as quickly as it is safe to do so. The first project, which focused on slope stabilization and debris removal at the site of the rockslide near Diablo Lake (milepost 131) has completed work. WSDOT moved the west side closure point to Ross Dam Trailhead (milepost 134) on May 30.
The second emergency contract began work May 13, 2026, and focused 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 of SR 20 between the Canyon Creek Trailhead and Granite Creek vicinities (mileposts 142-148). That work finished June 14, and SR 20 fully reopened.
What to expect
No traffic control is expected. The North Cascades Highway fully reopened on Sunday, June 14.
Crews will be making several repairs along SR 20 after winter storm damage. The North Cascades Highways will remain closed between Ross Dam Trailhead and Porcupine Creek (mileposts 134 to 156) until repairs are complete.
December washouts
On Dec.12, heavy rainstorms called atmospheric rivers hit the area. The storms caused debris, mud and water to block an SR 20 culvert near milepost 145. With the culvert blocked, water flowed along the side of the highway, washing away a ditch and undermining the shoulder and part of the eastbound lane. Dirt and rocks that used to support the road were carried down the ditch and blocked several more culverts. In some spots, the material piled up, forcing water to cross over the highway and wash away the embankment to the center line.
Water also washed away the ground under the remaining lane, so it is not safe to let anyone use this part of the road until it is repaired. This includes bikers and hikers. In some places, the pavement is hanging in the air with nothing underneath it.
In all, there were:
- Three locations where the embankment supporting the roadway needs to be rebuilt
- More than 1,000 feet of lane that has been undermined or collapsed
- One to 2 miles of damaged or collapsed asphalt shoulder
- Two to 3 miles of ditch line that needs to be repaired
- More than 1,000 feet of damaged guardrail and/or concrete barrier
- Approximately 15 culverts that are damaged or covered by debris.
- Slopes above the roadway that must be stabilized
- A number of other sections of the highway between mileposts 142 and 148 also were damaged and need repairs.
This work finished June 14, and North Cascades was fully reopened.
March rockslide
During another atmospheric river event March 17, a rockslide occurred near Diablo Lake (milepost 131). The slope that slid was approximately 200 feet wide. Approximately 4,000 cubic yards of material needed to be removed. Crews stabilized the slope by scaling, or closely examining every portion of it and dislodging loose rocks and debris. They then drilled holes in the rock face to anchor 20- to 60-foot steel dowels in a pattern designed by geotechnical engineers to stabilize the slope. This work finished on May 30.
Why is SR 20 taking longer to repair than US 2 did in December?
While the damage may look similar at first glance, the conditions at the two locations are very different, and those differences have had a major impact on how quickly crews could safely assess the damage and begin repairs.
One of the biggest factors is elevation. The primary damage sites on SR 20 are around 2,170 feet in elevation, while the damaged area in Tumwater Canyon on US 2 is closer to 1,500 feet. That higher elevation meant much of the SR 20 damage stayed buried under snow well into the winter, preventing crews from safely accessing and fully assessing the roadway until March.
Getting to the damaged areas on SR 20 also required crews to travel through avalanche chutes, creating additional safety risks and limiting when engineers and contractors could safely enter the corridor. Those same avalanche hazards were not present in Tumwater Canyon.
The scale of the damage is also different. On SR 20, crews are dealing with multiple damaged locations spread across roughly 6 miles between mileposts 142 and 148, in addition to the recent rockslide near milepost 131. Each of those locations required separate inspections and evaluations by geotechnical and hydraulic engineers before repairs could even begin to be designed.
In several areas, the damage extends beneath the roadway surface, where water undermined the structural support below the pavement. Crews are also evaluating unstable slopes, damaged drainage systems and locations where portions of the roadway may need to be rebuilt.
All of those factors: elevation, snowpack, avalanche risk, accessibility and the overall scale of the damage have directly affected the repair timeline on SR 20. That said, the goal on both highways is the same: to safely reopen the road as quickly as possible.
