Rock scalers have wrapped up their cliffside work above State Route 20 near Diablo Lake and are now breaking out the heavy drills, with crews boring into the rock face to install long anchor dowels meant to keep the mountainside in place. The western stretch of the North Cascades Highway remains closed to all travel, and the public is being kept well away from the work zone while crews stage equipment and shore up a route battered by severe winter flooding and a March rockslide that undermined portions of the road.
In an update posted Monday, WSDOT said crews have finished scaling the slope and are shifting to drilling and installing 20 to 60 foot anchor dowels to further stabilize the hillside. The agency also reiterated that people need to stay out of the closure area while the work continues, since crews are operating directly above the roadway.
Work zone and access restrictions
The closure covers roughly mileposts 130 to 156, from the Colonial Creek and Diablo Lake area east toward Porcupine Creek, and it applies to drivers and recreational users alike. Local reporting says WSDOT has explicitly prohibited hiking, biking and camping inside the work zone while crews are on the hillside, as reported by KIRO 7.
Why the repairs are extensive
State officials say the trouble is not a single rockfall that can be scooped up and hauled away. Winter floodwaters undermined roadway material in several locations, and a March event produced a large slope failure near Diablo Lake. “This isn’t just clearing debris,” WSDOT Assistant Region Administrator Melissa Ambler told KUOW, noting that in some spots crews must rebuild the road from the ground up.
Timeline and what to expect
WSDOT says it authorized emergency stabilization work to begin in early May but has not put a firm date on when the western corridor might reopen. According to the agency’s project description, this round of repairs will require multiple contracts and could take several weeks, depending on weather and permitting. For more on the schedule and scope, see WSDOT.
Local impact
The extended shutdown keeps long detours in place and looms over the crucial spring and summer season for communities that depend on Highway 20 visitors. Lawmakers and business owners have pushed the department for clearer expectations after reports of cancellations and lost bookings, a concern highlighted by Rep. Hunter Abell in coverage by KUOW.
Officials are asking travelers and outdoor enthusiasts to respect the closure signs and stay out of the area while the stabilization work is underway. WSDOT plans to post further updates on its project page and social channels as construction progresses.
