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 States Environmental Protection Agency,
National Health and Environmental Effects Research Laboratory (NHEERL)-
Corvallis, OR., the U.S. Forest Service, Natural Resources Conservation
Service, Washington State Department of Natural Resources & 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.