The Upper Missouri watershed, covering parts of Montana, Wyoming, and South Dakota, has a land area of approximately 54,000 square miles. It is characterized by a semi-arid climate with low annual precipitation, leading to a reliance on snowpack for water supply. This snowpack is primarily found in the Rocky Mountains and the Big Belt Mountains. Surface water in the watershed includes the Missouri River, Clark Fork River, and Yellowstone River, along with numerous smaller streams and tributaries. The watershed also contains several reservoirs, including Canyon Ferry Reservoir and Hauser Reservoir. The most significant constituent in these reservoirs is sediment, which can impact water quality and storage capacity. Interesting climatic facts in the watershed include the occurrence of extreme weather events such as droughts and floods, as well as a trend of increasing temperatures and decreasing snowpack due to climate change.