2017 Map of Arsenic Mountain

About this map

Arsenic Mountain dominates the center of this landscape within the Lewis & Clark National Forest, where the complex drainage systems of the Montana Rockies converge. The southern portion of the quadrangle is defined by the meeting of the North Fork Sun River and the South Fork Sun River, where the waters begin to pool into the Gibson Reservoir. This area reveals the transition from high-elevation peaks like Sheep Reef to the low-lying Reclamation Flats. The map documents numerous remote features such as Medicine Springs and the geological formations of The Bars and Sun Butte. These features, along with the deep cuts of Blacktail Gulch and Mortimer Gulch, illustrate a wilderness defined by its water sources, from the small Arsenic Cr to the major river forks that sustain the regional ecosystem.