UPDATE 2:30 p.m. Wednesday, April 12
State Route 530 near Oso reopened at 2:26 p.m. Wednesday, April 12, following an emergency closure due to an unstable slope above the highway.
Over the past weekend, crews installed 11 monitoring locations to track ground movement and analyzed the hillside twice a day. After several days of no measurable movement to the slide area above SR 530, geologists from the Department of Natural Resources (DNR) and the Washington State Department of Transportation (WSDOT) have decided to reopen the highway.
Snohomish County officials have also lifted the voluntary evacuations for residents near the slide area.
“We want to thank everyone for their patience as we waited to reopen the roadway,” WSDOT Assistant Regional Administrator Dave McCormick. “We know this is a vital path for many folks and appreciate your understanding as we worked to keep residents safe and track any movement of this 24-acre slide.”
While the highway has reopened, WSDOT will continue to monitor the slide area.
“The highway could close again if crews detect significant ground movement,” said McCormick. We will continue to track this slide carefully.”
UPDATE 8:30 a.m. Wednesday, April 12
No movement noted this morning on the SR 530 slide area.
UPDATE 4:40 p.m. Tuesday, April 11
WSDOT crews found no active slide movement on the slope this afternoon. Another update will be provided Wednesday morning.
UPDATE 8 a.m. Tuesday, April 11
This morning, WSDOT crews found no active slide movement on the slope.
UPDATE 5 p.m., Monday, April 10
This afternoon, WSDOT crews found no active slide movement on the slope. Our crews will continue to monitor the hillside, and will provide another update Tuesday morning.
UPDATE Noon, Monday, April 10
This morning, WSDOT crews found no active slide movement on the slope. We will continue to provide updates twice a day as our crews continue to monitor the hillside.
|Maps showing closure area|
State Route 530 near Oso will remain closed to drivers until at least Thursday, April 13 due to an unstable slope above the southwest side of SR 530. The road is closed between Oso Loop Road (MP 34) and C-Post Road (MP 38). The closure began on Friday, April 7.
WSDOT geologists have spent the past two days analyzing data, and tracking movement of a slow moving landslide approximately 300 feet above SR 530. While no additional movement was detected, geologists believe the slide still has the potential to move. Geologists want additional time to observe the slide area before the highway can be reopened to traffic.
"If the entire 24 acre slide were to give way, it could completely cover highway 530 and potentially reach Whitman Road," said Assistant Regional Administrator Dave McCormick. "We know this is huge disruption to the lives of those who live and work in the Stillaguamish River Valley, but there's still a heightened risk that this slide could still move."
During the closure, drivers who need to travel between Oso and Darrington must use SR 20, which will add at least one hour to a one-way trip. Emergency vehicles and property owners inside the road closure will be allowed through the area.
Unstable slope information
During survey work on Saturday, April 8, geologists with the Department of Natural Resources (DNR), WSDOT and representatives from Snohomish County, the Snohomish County Sheriff's Office and Seattle City Light observed and mapped areas of movement within a previously known landslide. Geologists also installed 10 monitoring locations to track ground movement. The slide is located approximately 1.5 miles southwest of the 2014 SR 530 landslide.
Voluntary evacuation advisory remains in place
A voluntary evacuation notice issued by the Oso Fire Department and Snohomish County Sheriff's Office to approximately a dozen nearby homes remains in effect.
On Monday, April 3, crews working for WSDOT were notified about ground movement near Montague Creek along the south side of SR 530 and approximately a half-mile from Skaglund Hill.
On Friday evening, April 7, DNR crews observed additional ground movement at the site. Heavy rains most likely contributed to the ongoing ground movement. While this is a slow moving slide, DNR and the Washington State Patrol asked WSDOT to temporarily close SR 530 as a safety precaution.
Joint agency response
DNR, WSDOT, Oso Fire Department, Snohomish County, Snohomish County Sheriff's Office and the Washington State Patrol will continue to work together over the next several days while the highway remains closed and ground conditions are closely monitored.