Description: This data layer is an element of the Oregon GIS Framework. Ecoregions denote areas of general similarity in ecosystems and in the type quality, and quantity of environmental resources. This map depicts revisions and subdivisions of ecoregions that was compiled at a relatively small scale (Omernik 1987). Compilation of this map, performed at the larger 1:250,000 scale, was part of a collaborative project between the United StatesEnvironmental Protection Agency, National Health and Environmental EffectsResearch Laboratory (NHEERL)- Corvallis, OR., the U.S. Forest Service, Natural Resources Conservation Service, Washington State Department of Natural Resources and the Oregon Natural Heritage Program. The ecoregions and subregion are designed to serve as a spatial framework for environmental resource management. The most immediate needs by the states are for developing regulations, biological criteria and water quality standards, and for setting management goals for nonpoint-source pollution. Explanation of the methods used to describe the ecoregions are given in Omernik (1995), Griffith et al. (1994), and Gallan et al. (1989). This map is a draft product of one of a few regional interagency collaborative projects aimed at obtaining consensus between the EPA, the NRCS, and the USFS regarding alignments of ecological regions.