2011 Map of Lost Horse Plateau

About this map

Lost Horse Plateau dominates this high-country landscape in Yakima County, defined by a complex network of drainages and Bureau of Indian Affairs (BIA) routes. The terrain is deeply incised by Toppenish Creek and its many tributaries, including North Fork Toppenish Creek and Branch Creek. This 2011 survey reveals a landscape largely shaped by seasonal water and traditional land use, as evidenced by Olney Corral situated near the junction of Wahtum Creek and the historical Fort Simcoe Rd. While much of the area is remote, the web of designated routes like BIA 311 Rd and BIA 180 Rd underscores the ongoing management and reach of tribal and agency operations across the plateau. To the north, the headwaters of the South Fork Simcoe Creek flow toward the lower valleys, tracing the edges of the high plateau country.