This incredibly comprehensive and well-organized site from the USGS offers visitors all sorts of information on water quality studies from all over the United States. By clicking on a map of the US, users are taken to a list of study areas, with over fifty to pick from. By clicking on an individual study, such as the Western Lake Michigan Drainages, the user is provided with a description of the study, maps, publications, and water quality information. As part of the USDS and initiated in 1991, the National Water Quality Assessment (NAWQA) been "systematically collecting chemical, biological, and physical water quality data." Since then, over 6,000 surface water sites and 7,000 wells have been sampled represented by tens of thousands of samples. This data is summarized for visitors to the site and should be very useful for those studying surface water quality and educators looking for recent data to augment their teaching.