The Great Basin Watershed covers 362,600 km (140,110 mi2) and extends from the Sierra Nevada Range in California to the Wasatch Range in Utah, and from southeastern Oregon to southern Nevada (NBC Weather Plus Website). The region is among the driest in the nation and depends largely on winter snowfall and spring runoff for its water supply. Precipitation may be as much as 127 cm (50 inches) in high mountains, but many lower elevation desert areas receive only about 13 to 18 cm (5 to 7 inches) annually (State of Utah, Division of Water Resources webpage). Water supply can vary dramatically from year-to-year, and farms, cities, towns, and industries rely on the efficient use of reservoirs that capture spring snowmelt for distribution later in the year. When snow and rain are insufficient to fill reservoirs, farm yields are reduced, groundwater aquifers recede, and water restrictions can be imposed. Most of the region’s water resources are fully appropriated with irrigation accounting for over 70 percent of water use in Nevada and Utah. As the region’s population continues to grow, water is being converted from agricultural to urban use and groundwater sources are being used more extensively.