Since its inception in 1991, the USGS National Water-Quality Assessment (NAWQA) program has been collecting and analyzing data about more than 50 major river basins and aquifers across the United States. The core mission is "to develop long-term consistent and comparable information on streams, ground water, and aquatic ecosystems to support sound management and policy decisions." Visitors can begin by selecting one of over 50 research sites from a drop-down menu of states, or by looking at research activities by river basin. The main homepage for the NAWQA also contains a section that explains how and why water quality varies across the country by discussing the various elements, such as pesticides and nutrients, that contribute to the quality of various water sources. Of course, the site also features a number of more technical reports on water quality, including detailed information about each basin area. As might be expected, the site also offers a glossary of frequently used terms within the fields of water chemistry and hydrology, and also contains a What's New section that contains announcements about the release of new reports, fact sheets, and upcoming conferences of note.