Highway 9 between East College Way and Mount Vernon Big Lake Road will be closed intermittently Friday, July 19, because of a nearby wildfire, the state Department of Transportation said.
The closure is necessary so crews from the Washington State Department of Natural Resource can safely make aerial drops on a nearby wildfire.
Northbound drivers will follow a marked detour to Mount Vernon Big Lake Road, then to East Division Street, to North Waugh Road and then onto East College Way. Southbound traffic is being routed onto East College Way.
The Skagit Valley Herald reports no homes have been threatened and cool, damp weather is assisting firefighters.
The Big Rock fire is named for a 500-foot-high local landmark, which is popular spot for hiking and mountain bikers, although it is not technically open to the public.
The Washington Department of Natural Resources reports the fire is burning in trees on rocky, steep terrain.
Fire officials have not determined the cause but suspect it might have started with a campfire.