The Lower Belle Fourche watershed covers approximately 3,610 square miles in northeastern Wyoming and western South Dakota. The area is characterized by high precipitation rates, primarily in the form of snow, which contributes to a significant snowpack. This snowpack serves as a vital source of water for the area's surface water and reservoirs. The watershed is home to several reservoirs, including Keyhole Reservoir, which contains elevated levels of selenium due to natural mineral deposits in the surrounding geology. The area experiences a semi-arid climate, with hot summers and cold winters. In recent years, the region has seen an increase in average temperatures, leading to changes in snowmelt patterns and earlier runoff. Overall, the Lower Belle Fourche watershed plays a critical role in providing water resources to the surrounding communities and supporting agriculture and other industries in the region.