Aquatic Ecoregions in the United States GIS Data for the EPA Clean Air Mapping and Analysis Program (C-MAP)

Ecoregions are based on perceived patterns of a combination of causal and integrative factors including land use, land surface form, potential natural vegetation, and soils (Omernik, 1987). This is a copy of the ecoregion coverage of Omernik (1987) with some item names modified. This coverage is intended for national-level studies of water resources. Reviews_Applied_to_Data. The Ecoregions were plotted on a terminal to ensure the EXPORT file was imported properly. No claims are made regarding the accuracy of the original data or linework. [Summary provided by the EPA]