Water Use in the United States
Irrigation Water Use
Irrigation water use includes water that is applied by an irrigation system to sustain plant growth in all agricultural and horticultural practices. Irrigation also includes water that is used for pre-irrigation, frost protection, application of chemicals, weed control, field preparation, crop cooling, harvesting, dust suppression, and leaching salts from the root zone. Estimates of irrigation withdrawals include water that is lost in conveyance prior to application on fields as well as water that may subsequently return to a surface-water body as runoff after application, water consumed as evapotranspiration (ET) from plants and ground surfaces, or water that recharges aquifers as it seeps past the root zone.
Irrigation of golf courses, parks, nurseries, turf farms, cemeteries, and other self-supplied landscape-watering uses also are included in the estimates. Irrigation water use includes self-supplied withdrawals and deliveries from irrigation companies or districts, cooperatives, or governmental entities. Some irrigation water is reclaimed wastewater from nearby treatment facilities or industries. Reclaimed wastewater use for irrigation was last reported for 1995. All irrigation withdrawals are considered freshwater. Irrigated acres are reported by three types of irrigation methods: sprinkler, microirrigation, and surface (flood) systems.
2010 Water Use
(source: Maupin, M.A., Kenny, J.F., Hutson, S.S., Lovelace, J.K., Barber, N.L., and Linsey, K.S., 2014, Estimated use of water in the United States in 2010: U.S. Geological Survey Circular 1405, 56 p., http://pubs.usgs.gov/circ/1405/.)
For 2010, total irrigation withdrawals were 115,000 Mgal/d, which accounted for 38 percent of total freshwater withdrawals. Withdrawals from surface-water sources were 65,900 Mgal/d, which accounted for 57 percent of the total irrigation withdrawals. Groundwater withdrawals for 2010 were 49,500 Mgal/d.
About 62,400 thousand acres were irrigated in 2010, 31,600 thousand acres (51 percent) with sprinkler systems, 26,200 thousand acres with surface (flood), and 4,610 thousand acres with microirrigation systems. The national average application rate for 2010 was 2.07 acre-feet per acre.
The majority of total U.S. irrigation withdrawals (83 percent) and irrigated acres (74 percent) were in the 17 conterminous Western States (west of solid line in map above). Surface water was the primary source of water in the arid West, except in Kansas, Oklahoma, Nebraska, Texas, and South Dakota, where more groundwater was used.
Irrigation withdrawals were 9 percent less between 2005 and 2010, a level not reported since before 1965, althoughotal irrigated acres increased 2 percent. The use of more water-efficient irrigation systems continued to increase with nearly 3 percent more irrigated acres using sprinkler systems in 2010 than in 2005.
Sources of data for irrigation withdrawals and irrigated acres include State and Federal crop reporting programs, irrigation districts, canal companies, incorporated management areas. For the 2010 estimates, satellite data depicting 2010 cropland landscapes was also used for some States. Withdrawals also are estimated using information on irrigated crop acreages by crop type and specific crop water-consumption coefficients, or irrigation-system application rates, as well as soil moisture balance models. Estimation methods vary from one State to the next and sometimes between geographic areas within a State. Estimation methods ideally include adjustments for climate, system efficiencies, conveyance losses, and other irrigation practices such as pre-irrigation, salt leaching, or frost protection. Other methods for estimating irrigation withdrawals included extrapolation of sample data on crop water-application rates or power-consumption coefficients.