Polygons of the Level III ecoregions in Arizona for the conterminous United States. The coverage is stored in the EPA Spatial Data Library System (ESDLS). The ecoregions shown here have been derived from ecoregions of the conterminous United States and from refinements of Omernik's framework that have been made for other projects. These ongoing or recently completed projects, conducted in collaboration with the U.S. EPA regional offices and with state resource management agencies, involve refining ecoregions, defining subregions, and locating sets of reference sites. These are designed to serve as a spatial framework for environmental resource management.
Source: atlas.library.arizona.edu/atlas/dataDownloader