The website, "Diatoms of the United States" is up and running. The site is designed for the beginner to expert user integrates diatom taxonomy, nomenclature, reference images, maps, sample information, species count data, literature references, and ecological analysis. With the section, "By Morphology", users can use visual keys to navigate to genus and species identification. Using the "Taxon Search", expert users can search by any part of a diatom genus or species name. The site promotes taxonomic consistency by analysts working on state and federal programs, including the USGS National Water Quality Assessment program. In particular, this resource allows agencies to implement EPA recommendations to accurately assess diatom assemblages, thereby supporting compliance with the Clean Water Act. The guide built for this project is a pilot, with species pages for 25 initial species. In 2010, the USGS is funding expert contributors to include 200 more species pages and expansion of the geographic coverage of the site to the entire U.S. We welcome interested contributors to contact Sarah Spaulding.