This paper discusses the programmes of the National Water Data Exchange (NAWDEX) in providing access to US Geological Survey (USGS) water data and water-related information. NAWDEX dissseminates water data and water-related information by working cooperatively through a network of 68 Assistance Centers to more than 430 member organizations. In addition, NAWDEX provides access to the USGS Water Data Storage System (WATSTORE) and the US Environmental Protection Agency's Storage and Retrieval System (STORET). Recently, the trend has been to make water resources data available over the World Wide Web on the Internet. The NAWDEX homepage, located at Uniform Resource Locator http://h2o.er.usgs.gov/public/nawdex/nawdex.html, provides links to (a) Selected Water Resources Abstracts; (b) National Water Conditions Report; (c) historical streamflow data: and (d) real-time streamflow conditions. NAWDEX also transfers data to users over the Internet through the file transfer protocol (FTP).