The USGS has a distributed water database called the National Water Information System (NWIS) that is locally managed. Surface-water, ground-water, and water-quality data are rolled up from these local, distributed databases into a national system. The ground-water database contains records from about 850,000 wells that have been compiled during the course of ground-water hydrology studies and data-collection activities over the past 100 years. Information from these wells has been served via the Internet since 2001 through NWISWeb. NWISWeb provides all USGS ground-water data that are approved for public release. This large number of wells is excellent for some uses, but complicates retrievals when the user is interested in specific networks, or groups of wells with similar characteristics.  Moreover, periodic (infrequent measurements made manually) and continuous (daily values or more frequent measurements made with automated recorders) data are processed and stored in different NWIS subsystems, so NWISWeb must serve these data separately.  To address the potentially overwhelming number of wells, and the fact that different types of data must be obtained through different retrievals, the USGS has developed three additional data presentation/data discovery tools for ground-water level data.