2020 Map of Lost Horse Plateau

About this map

Lost Horse Plateau and Lincoln Plateau define the high terrain of this portion of Yakima County, where numerous watercourses descend toward the southeast. The drainage network is particularly dense here, featuring the winding paths of Toppenish Cr, the N Fork Toppenish Cr, and Agency Cr. This landscape is marked by a network of Bureau of Indian Affairs routes, including Bia RD 187 and Bia RD 211, which navigate the steep topography between the plateaus and deep cuts like Old Maid Canyon. The arrangement of these roads and the inclusion of Fort Simcoe Rd suggest a modern infrastructure built around the historic boundaries of t10n r14e and t9n r14e. The area is defined by its transition from high ridges down to the creek beds of S Fork Simcoe Cr and Wahtum Cr.