The Fort Pierre National Grassland is federal land and covers 116,000 acres south of Fort Pierre, north of Interstate 90, and west of the Lower Brule Indian Reservation. The topography ranges from flat to gently rolling hills to relatively steep slopes and creeks that flow toward the Bad River and the Missouri River.
Numerous drainage areas have been dammed to create small to medium-sized ponds that provide water for wildlife and livestock. Many ponds are important for waterfowl habitat and popular fisheries. The Fort Pierre National Grassland is a primarily mixed-grass prairie vegetation and home to many species of wildlife.