The Rapid watershed (HUC 09030007) encompasses an area of around 1,361 square miles in South Dakota. The hydrology of the region is dominated by the Cheyenne River, which is the main source of water for the Rapid watershed. The watershed receives a significant amount of snowfall during the winter months, with the highest snowpack observed in the upper elevations of the Black Hills. This snowpack contributes to surface water runoff during the spring and summer months, providing water for irrigation, recreation, and other uses. Reservoirs within the watershed, including Pactola and Deerfield, play a crucial role in regulating the flow of water within the region. Interesting climatic facts include the frequent occurrence of thunderstorms and tornadoes during the summer months. Increasing temperatures and changing precipitation patterns are being observed in the region, leading to concerns about the impact of climate change on the watershed.