The Big Sandy Watershed (HUC 15030201) covers an area of approximately 1,816 square miles in Wyoming and Montana. It is home to several major rivers and tributaries, including the Big Sandy River, the Little Bighorn River, and the Lodgepole Creek. The watershed is characterized by a semi-arid climate, with low precipitation levels and high evapotranspiration rates. The area also experiences significant snowfall during the winter months, which contributes to the surface water and reservoir levels in the spring and summer. The primary constituents of the reservoirs in the watershed are sediment and dissolved organic matter. Recent climatic trends in the area include warming temperatures and changes in precipitation patterns, which are expected to have significant impacts on the hydrology and ecology of the watershed in the coming decades.