Wyoming Surface Water
All the snow and rain that falls on Wyoming goes into the ground, evaporates, or becomes surface water. Mountain snow is the main source of Wyoming’s surface water. The majority of snowpack is concentrated in a relatively small area. This small land area is responsible for the majority of Wyoming’s runoff and surface water supplies.
Surface water takes on many forms: snow, glaciers, creeks, rivers, ponds, lakes, and marshes. This water is vital for people and Wyoming wildlife and their habitats. Surface water supplies the majority of the municipal and agricultural needs of the state. And due to the seasonal nature of this water source, Wyoming utilizes a variety of dams, reservoirs, and hydropower for managing the state’s surface water resources.
The use of Wyoming’s water is managed by the Wyoming State Engineer’s Office. The Wyoming Department of Environmental Quality monitors water quality. These agencies serve important roles in the management of Wyoming’s water resources. Any events – changes in climate, drought, vegetation change, fires, insect outbreaks – that impact our mountain watersheds will have major consequences for all Wyoming water users, as well as for water users downstream.
Wyoming is the fifth driest state in the United States. More than 70 of the state receives less than 16 inches of precipitation on average each year. Wyoming also has the second highest mean elevation in the United States at 6,700 feet. Mountain snowpack runs off to form the headwaters of Wyoming’s major river systems and helps recharge aquifer systems.
Three of America's major river systems have their headwaters in Wyoming: the Missouri, the Colorado, and the Columbia. Other major rivers include the Yellowstone, the Bighorn, the North Platte, the Green, and the Snake.
Surface Water Resource Map of Wyoming: Streamflows and Storage
The Wyoming State Geological Survey (WSGS) in 2009 released a map showing stream flows and surface water storage in Wyoming. This unique and comprehensive map product includes current and historic streamflow and reservoir capacity data.
The map with accompanying CD illustrate the minimum, average and maximum streamflow rates at 330 U.S. Geological Survey (USGS) gage locations across Wyoming and the maximum storage capacities of reservoirs and volumes of major lakes. The map also features watershed boundaries, surface water facts and trivia, tables of the 10 largest lakes and rivers, and inset maps of structural geology and the headwaters and routes of Wyoming rivers.
Additional Surface Water Information