Drivers heading along state Route 161 between Eatonville and Alder this weekend should expect delays.
The route is being used as a detour around a closed section of state Route 7 near LaGrande, which was closed in June after a landslide.
State Department of Transportation geotechnical engineers are still studying the cause of the slide, the condition of the hill and designing how to repair the damage.
Officials said heavy traffic is expected through the detour over the weekend, especially Friday and Sunday. Washington State Patrol troopers will be providing traffic control at the SR 161 and Alder Cutoff Road intersection in the afternoon and evenings.