Every five years since 1950, the U.S. Geological Survey (USGS) National Water Use Information Program (NWUIP) has compiled water-use information in the United States and published a circular report titled "Estimated use of water in the United States," which includes estimates of water withdrawals by State, sources of water withdrawals (groundwater or sur-face water), and water-use category (irrigation, public supply, industrial, thermoelectric, and so forth). This report discusses the impact of important considerations when estimating irri-gated acreage and irrigation withdrawals, including estimates of conveyance loss, irrigation-system efficiencies, pasture, horticulture, golf courses, and double cropping.