Gitchie Manitou State Preserve is located in the northwesternmost corner of Iowa, in the W½, Sec. 11, T. 100N., R. 49W., about 9 mi (14,5 km) northwest of Larchwood in Lyon County, Iowa (Fig. 1). The preserve is situated in the valley of the Big Sioux River, which forms the western limits of the preserve and the boundary between Iowa and South Dakota. The highest elevation within the preserve is about 1,286 ft (392 rlevel, about 40 ft (12 m) above river level but about below the elevation of nearby upland areas.