Water - USNPS
Water plays an incredible role in the ecosystems of Yellowstone National Park and the surrounding areas.
The water that flows through Yellowstone National Park and the Greater Yellowstone Ecosystem (GYE) is a vital national resource. The headwaters of seven great rivers are located in the GYE, and flow from the Continental Divide through communities across the nation on their way to the Pacific Ocean, the Gulf of California, and the Gulf of Mexico. Precipitation (rain and snow) in the mountains and plateaus of the Northern Rockies flows through stream and river networks to provide essential moisture to much of the American West; and water resources provide recreational opportunities, plant and wildlife habitat, and scenic vistas.
Water also drives the complex geothermal activity in the region and fuels the largest collection of geysers on earth. Precipitation and groundwater seep down into geothermal “plumbing” over days, and millennia, to be superheated by the Yellowstone Volcano and rise to the surface in the form of hot springs, geysers, mudpots, and fumaroles.
Yellowstone contains some of the most significant, near-pristine aquatic ecosystems found in the United States. More than 600 lakes and ponds comprise approximately 107,000 surface acres in Yellowstone—94 percent of which can be attributed to Yellowstone, Lewis, Shoshone, and Heart lakes. Some 1,000 rivers and streams make up approximately 2,500 miles of running water. Thousands of small wetlands—habitats that are intermittently wet and dry—make up a small (approximately 3%) fraction of the Yellowstone landscape.
The quality of the nation’s waters is protected by laws and policy at local, state, and federal levels. To understand and maintain or improve water quality and aquatic ecosystems, resource managers take inventory and actively monitor water resources throughout the region. Water quality in a national park may reflect activities taking place upstream of the park’s surface waters as well as within the park. The water quality in Grand Teton and Yellowstone national parks, where most of the watersheds originate on federally protected land, is generally very high. However, it is vulnerable to impacts such as road construction, recreational activities, and deposition from atmospheric pollutants.
All Yellowstone waters are classified as Outstanding National Resource Waters, which receive the highest level of protection for surface waters under the Clean Water Act. Because of the relatively pristine nature of the park’s surface waters, they are often used to establish reference conditions for the northern Rocky Mountain region. Although most of the park’s watersheds originate within its boundaries and are minimally affected by human activities, they are vulnerable to impacts such as road construction, dewatering, atmospheric deposition, sewage spills, climate change, and runoff from mining sites outside park boundaries.