All lanes on Interstate 5 northbound reopened late Saturday afternoon after a morning landslide pushed trees and mud into the road south of Bellingham, near milepost 244.
No one was injured in the slide, which happened at about 8:15 a.m. just north of the Skagit County line, said Washington State Patrol spokesman Trooper Rocky Oliphant. It took hours to clear the debris and assess the stability of the slope where the landslide occurred.
The road reopened around 4:45 p.m., according to the Washington State Department of Transportation (WSDOT).
The slide, which damaged the guardrail, was about 60 feet wide and 7 feet deep, according to the State Patrol.
Traffic had been detoured at Nulle Road, according to WSDOT. Engineers assessed the slope and determined it was safe to clear the debris, the department said.
The area near the slide has received about 3 inches of rain in the latest storm that began Thursday night, said Brent Bower, a hydrologist at the National Weather Service in Seattle. The agency issued an alert about a heightened risk of landslides.
It’s not just rainfall that raises the possibility of landslides, but persistent rain that leaves the ground soaked, like the region has seen in recent days, Bower said.
Given current conditions, “any significant rainfall has the capability of triggering [landslides],” Bower said.
Still, this season has been relatively normal in the number of slides, Bower said. Landslides this winter have happened throughout the Puget Sound region and on the Olympic peninsula.
Slides are most likely in places with steep geology and muddy soil, like coastal bluffs, Bower said. Tracking landslides can be imprecise, since they are not always reported if they don’t affect a roadway or attract media attention, Bower said, and it’s not always clear why a slide happens in one place and not another.
“There’s a certain randomness feel to it,” Bower said. “We can’t get to the point of issuing warnings for any specific place and time, but it is a danger and we can alert people to that.”
Warning signs of a potential landslide include new or developing cracks or bulges in the ground, sagging or taut utility lines, leaning telephone poles and separation of structures from their foundation, according to the Washington State Department of Natural Resources (DNR). Rainfall, earthquakes and human activities such as excavation can trigger landslides.
DNR encourages people to make a landslide emergency plan, take care to watch for debris on the roadway and listen for loud or unusual sounds, like the sound of cracking wood, that can indicate an imminent landslide.
Staff reporter Scott Greenstone contributed to this report.