The Fort Peck Reservoir watershed (HUC 10040104) covers approximately 21,000 square miles in northeastern Montana. The area's hydrology is characterized by a semi-arid to sub-humid climate with an average annual precipitation of 14-16 inches. The watershed receives most of its water from snowmelt and spring runoff. The snowpack in the area varies greatly from year to year, with the most snow accumulation occurring in the lower elevations of the watershed. The main surface water source is the Missouri River, which flows through the Fort Peck Reservoir. The reservoir's constituents include sediment, nutrients, and contaminants such as mercury and PCBs. The area experiences extreme temperature fluctuations, with temperatures ranging from below zero in the winter to over 100 degrees Fahrenheit in the summer. Climate change has resulted in reduced snowpack and increased temperatures in the area, which could impact the watershed's hydrology and water resources.