Explanation of the methods used to define the EPA's ecoregions are given in Griffith et al. (1994), Omernic (1995), and Gallant et al. (1989).
Questions or comments regarding the methods used can be addressed to U.S. EPA NHEERL, 200 SW 35th Street, Corvallis, OR 97333, (503) 754-4465, FAX: (503) 754-4716
Scale is an important factor in data usage. Certain scale data sets are not suitable for some projects, analysis, or modeling purposes. Please be sure you are using the best available data.
1:24000 scale data sets are recommended for projects that are at the county level. 1:24000 data should NOT be used for high accuracy base mapping such as property parcel boundaries.
1:100000 scale data sets are recommended for projects that are at the multi-county or regional level. 1:250000 scale data sets are recommended for projects that are at the regional or state level or larger.