The Lower Tongue Watershed (HUC 10090102) covers an area of approximately 2,500 square miles in northeastern Wyoming and southeastern Montana. The watershed is characterized by a semi-arid climate, with average annual precipitation ranging from 12 to 16 inches. The hydrology of the watershed is dominated by the Tongue River, which flows for approximately 265 miles through the area. The river is fed by snowpack from the nearby Bighorn Mountains, which can reach depths of over 120 inches during the winter. Surface water in the watershed is primarily used for irrigation and recreation, and there are several reservoirs located along the Tongue River. These reservoirs provide water for agricultural use and generate hydroelectric power. Interesting climatic facts include the occasional occurrence of severe droughts, such as the one experienced in the early 2000s, and the tendency for winter temperatures to drop to below zero degrees Fahrenheit.