NHDPlus is a geo-spatial, hydrologic framework dataset envisioned by the US Environmental Protection Agency. NHDPlus is an
integrated suite of application-ready geospatial data sets that incorporate many of the best features of the National Hydrography
Dataset (NHD), the National Elevation Dataset (NED), the National Land Cover Dataset (NLCD), and the Watershed Boundary Dataset
(WBD). NHDPlus has been used to enhance the EPA WATERS application. Info for National Elevation, Hydrography, Land use, and
Watersheds.