The Knapps Hill Tunnel on Highway 97A will be closed from 8 a.m. to 2 p.m. Wednesday for a routine inspection.
The Washington State Department of Transportation said the highway will be closed between mileposts 223 and 230 with traffic detoured onto Navaree Coulee Road, which will add about 20 minutes to a trip between Wenatchee and Chelan.
WSDOT said the tunnel is inspected every two years to examine both the inside of the tunnel and the rocky slope above it.
During the closure, Link Transit will be rerouting its Wenatchee-to-Chelan bus to the other side of the Columbia River on Highway 97 through Orando.
During that time, shuttles will be available between Wenatchee and Entiat.