This dataset contains water-use estimates for 2015 that are aggregated to the county level in the United States. The U.S. Geological Survey's (USGS's) National Water Use Science Project is responsible for compiling and disseminating the Nation's water-use data. Working in cooperation with local, State, and Federal agencies, the USGS has published an estimate of water use in the United States every 5 years, beginning in 1950. Water-use estimates aggregated to the State level are presented in USGS Circular 1441, "Estimated Use of Water in the United States in 2015" (Dieter and others, 2018). This dataset contains the county-level water-use data that support the state-level estimates in Dieter and others 2018. This dataset contains data for public supply, domestic, irrigation, thermoelectric power, industrial, mining, livestock, and aquaculture water-use categories. First posted September 28, 2017, ver. 1.0 Revised June 19, 2018, ver. 2.0 Version 2.0: This version of the dataset contains total population data and water-use estimates for 2015 for the following categories: Public supply, domestic, irrigation, thermoelectric power, industrial, mining, livestock, and aquaculture. Data are aggregated to the county level. A value of "--" denotes that values were not estimated for an optional attribute. Some values in the public supply and domestic categories have been updated from those found in version 1.0 of this dataset. Version 1.0: This version of the dataset contains total population data and water-use estimates for the public supply and domestic categories for 2015 that are aggregated to the county level in the United States. A "--" in the attributes "PS-GWPop" or "PS-SWPop" denotes that values were not estimated for an optional attribute. All other occurrences of "--" denote data for an attribute in a water-use category that has not yet been released. Version 1.0 data are available upon request.