Yellowstone

Geography

The river rises in northwestern Wyoming in the Absaroka Range, on the Continental Divide in southwestern Park County. The river starts where the North Fork and the South Fork of the Yellowstone River converge. The North Fork, the larger of the two forks, flows from Younts Peak. The South Fork flows from the southern slopes of Thorofare Mountain. The Yellowstone River flows northward through Yellowstone National Park, feeding and draining Yellowstone Lake, then dropping over the Upper and Lower Yellowstone Falls at the head of the Grand Canyon of the Yellowstone within the confines of the park.

History

The Yellowstone River had long been an important artery of transportation for Native Americans. The region around the Big Horn, Powder and Tongue rivers is the traditional summer hunting grounds for numerous Native American tribes: Lakota Sioux, Crow, Cheyenne and Cree. Gold was discovered near Virginia City, Montana in the 1860s, and two of the primary routes for accessing the goldfields were the Bozeman Trail and the Bridger Trail both of which followed the Yellowstone for a short length. In the 19th century, European-American settlers depended on the river for transportation, and generally entered the region by riverboat.

Native American anger at settler encroachment on their hunting grounds led to Red Cloud's War.

Climate patterns

Flooding occurs in the watershed due to snowmelt, rainfall, and intense thunderstorms. In higher elevations, snowmelt can cause flood conditions due to rapid melt in spring and early summer. In lower elevations, regional rainstorms and intense thunderstorms can cause flooding in summer and fall.

Severe droughts have occurred in the Yellowstone Watershed that have lasted several years. Droughts have occurred in the basin in 1929–42, 1948–62 and 1976–82. The 1977 drought affected most of the western United States and resulted in decreased streamflows in the watershed. The reduced flow resulted in increased dissolved solids concentrations in the basin. Water quality varies across the various rivers in the basin.