Crews on Monday cleared avalanche debris off one lane of Highway 20 east of Newhalem.
State Department of Transportation spokeswoman Andrea Petrich said the lane opened about 12:30 p.m., allowing those trapped between the avalanche site near milepost 123 and the annual highway closure at milepost 134 to leave the area.
The avalanche covered a stretch of highway between Newhalem and Diablo early Friday, blocking the only route in and out of the Diablo area this time of year.
Crews were unable to begin clearing debris until Monday.
That left those in Diablo, a Seattle City Light company town, and at the North Cascades Institute’s Environmental Learning Center trapped for the weekend.
Residents and staff remain at those locations through the winter, and the environmental learning center continues to have visitors.
Spokespersons for Seattle City Light, which operates three dams on the upper Skagit River, and the North Cascades Institute, said everyone in the area was safe and had access to food and shelter.
Seattle City Light spokesman Scott Thomsen said several employees live in Diablo and Newhalem year-round, including dam operators and their families. Those residents are aware of the risks associated with living in remote areas of the North Cascades, he said, and are prepared for situations such as avalanches.
“From its (Seattle City Light’s) inception, this is one of the places where we literally worked our way into the wilderness to build the dams there,” Thomsen said. “The people who work there are hardy. They know things like this can happen and they are resilient.”
North Cascades Institute spokesman Christian Martin said some staff at the environmental learning center were planning to leave for the weekend, but instead found themselves entertaining a group that consisted mostly of 16-year-old students.
“Our staff really kicked into gear and showed how resourceful they are,” he said.
The 46 students from Jackson High School in Mill Creek were visiting the North Cascades Institute’s Mountain School with seven teachers and parent chaperones. The group planned to head home Friday, but because of the avalanche was unable to leave until Monday afternoon.
Environmental learning center staff organized extra lessons and activities to extend the students’ Mountain School experience through the weekend.
They coordinated a nature scavenger hunt, encouraging students to look for things such as specific types of trees and animal tracks in the snow, Martin said. They also offered an impromptu lesson using the center’s microscopes and an opportunity to examine the remains of dead birds.
“We didn’t get the sense that there was any fear. Just maybe being bummed not to be home or to be missing work,” Martin said.
The Mountain School program draws students from elementary, middle and high schools, and the institute tailors curriculum for each age group.
“We want to get kids (of all ages) out in nature and learning about it, getting hands-on experiences,” Martin said.
Because of the avalanche, Mountain School was canceled this week for Madison Elementary School in Mount Vernon and Acme Elementary School in Whatcom County.
The North Cascades Institute may also have to cancel a graduation event planned for this week. Several students are graduating through the Master of Education program the institute offers in partnership with Western Washington University.
“We have parents flying in from around the country to see their kids graduate ... We haven’t canceled yet, but we’re a little up in the air,” Martin said.
Petrich said the Department of Transportation will have one lane open through the week. The single lane is intended only for those trapped east of the avalanche to leave and for emergency vehicle access, she said.
The Department of Transportation does not know how long it will take to fully remove the avalanche debris and reopen the road.
The department will provide updates on Highway 20 traffic, including the status of the avalanche site, at 360-707-5055.