Yellowstone River

The Yellowstone River is a tributary of the Missouri River, approximately 692 miles long, in the Western United States. Considered the principal tributary of upper Missouri, this river, via its tributaries, drains a wide area, stretching from the Rocky Mountains in the vicinity of Yellowstone National Park, across the mountains and high plains of southern Montana and northern Wyoming.

The Yellowstone River watershed is a river basin spanning 37,167 square miles across Montana, with minor extensions into Wyoming and North Dakota, toward headwaters and terminus, respectively. The Yellowstone Basin watershed contains a system of rivers, including the Yellowstone River, and four tributary basins: the Clarks Fork Yellowstone, Wind River and Bighorn River, Tongue River, and Powder River. These rivers form tributaries to the Missouri River. The mainstem of the Yellowstone River is more than 700 miles long. At the headwaters, elevations exceed 12,800 feet above sea level and descends to 1,850 feet at the confluence with the Missouri River in North Dakota. The watershed spans 34,167 square miles. The area contains many lakes, including Yellowstone Lake. There is no storage dams located on the mainstem of the Yellowstone River. However, the watershed contains five major reservoirs: Bull Lake, Boysen, Buffalo Bill, Big Horn, Tongue River, and Lake De Smet reservoirs.

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