The 640-acre Grouse Flats unit is located in Garfield County about 65 miles southwest of the town of Asotin. Elevations range from 3,600 to 4,160 feet. It includes some ponds, but no year-round creeks or significant drainages.
Grouse Flats was acquired in 1967 with the intent to reduce elk damage complaints and establish a large continuous wildlife area. About 200 acres of open meadows are currently enrolled in a sharecrop agreement to improve big game forage. Small ponds have been developed to increase water available to wildlife, and salt is provided annually.
In addition to elk, Grouse Flats supports white-tailed and mule deer, turkey, ruffed and blue grouse, bear and cougar, and a multitude of non-game wildlife species including several state threatened and candidate species.