The U.S. Geological Survey (USGS) has compiled and published estimates of water withdrawals every 5 years since 1950. This series of water-use reports serves as one of the few sources of information about regional or national trends in water withdrawals (Hutson and others, 2004). In Wyoming, six categories.irrigation, mining, thermoelectric power, public supply, self-supplied domestic, and industrial.were included in the most recent (2000) USGS compilation of estimated water use. For each category, withdrawal volumes were compiled by water source (surface water or ground water), and by county. Irrigation, public supply, and industrial ground-water withdrawals also were compiled by aquifer. With the exception of saline ground-water mining withdrawals totaling 222 million gallons per day (Mgal/d), all withdrawals in Wyoming were freshwater. Estimated withdrawals are listed from largest to smallest throughout this fact sheet. Additional information on water use in Wyoming is available from the Wyoming Water Science Center water use website at http://wy.water.usgs.gov/projects/wateruse/index.htm.