USGS National Water Information System (NWIS)
Provides access to water-resources data collected at over 1.5 million sites in the 50 States and selected other areas. Data are organized by: o Current conditions—sites with real-time or recent surface-water, groundwater, or water-quality data. o Site information—descriptive site information for all sites with links to all available water data for individual sites. o Groundwater—water levels in wells. o Water quality—chemical and physical data for streams, lakes, wells, and other sites. o Water use—water-use information.