It was first reported Saturday afternoon east and south of Mill Hollow Reservoir, near the Duchesne Ridge.
It is burning timber in the Uinta-Wasatch-Cache National Forest.
The Heber-Kamas Ranger District has closed an area of the forest with a northern boundary of Highway 35, a southern boundary of Duchesne Ridge, a western boundary of Mill Hollow and an eastern limit of Wolf Creek campground.
Campers in the closed area are being asked to leave.
Engines, ground crews and helicopters are fighting the fire.
Smoke is visible in Summit and Wasatch counties. The public is asked not to report it.
