TWISP — The North Cascades Highway has only stayed closed through Memorial Day once in the past 40 years.

“But it could happen this year,” said Don Becker, maintenance supervisor in Twisp for the Washington State Department of Transportation.

Crews plan to start clearing Highway 20 on April 10, nearly a month later than the typical mid-March date. Clearing the 34-mile closed section usually takes four to six weeks, but this year it could take up to eight weeks.

Weather, snow slides and many still-full avalanche chutes make it unsafe to begin the work.

An avalanche closed the highway March 10, stranding 42 students from Jackson High School who were on a field trip at the North Cascades Institute’s Environmental Learning Center.

An avalanche is what prompted the highway’s initial closure this winter season, as well, back in November.

The latest reopening ever for the North Cascades Highway was June 14, 1974.

“An early opening is in time for the lowland fishing season opening, the third week in April. A typical opening is by the first weekend in May for Winthrop’s ’49er Days,” Becker said in a press release.

On a March 16 assessment trip, WSDOT avalanche and maintenance staff found snow 25 feet deep on the highway under four of the 11 Cutthroat Ridge avalanche chutes. Below Liberty Bell Mountain, the three main chutes were still full of snow but had 35- to 45-foot accumulations on the highway below them.

Once the clearing begins, bicyclists and skiers are allowed beyond the closure gates Friday through Sunday, but not Monday through Thursday when WSDOT crews are working.

Learn more

More information is at www.wsdot.wa.gov/traffic/passes/northcascades.