{276FEF2F-1C16-4615-AC10-B79FC4259FDE} eng; USA utf8 dataset Marc Weber U.S. Environmental Protection Agency, Office of Water Geographer (541) 754-4491 200 S.W. 35th Street Corvallis OR 97333 weber.marc@epa.gov https://www.epa.gov/aboutepa/about-office-water pointOfContact 2026-06-02 ISO 19115 Geographic Information - Metadata ISO 19115:2003/Cor.1:2006(E) complex 1631 Omernik's Level III Ecoregions Of The Conterminous United States 2013-04-16 publication U.S. EPA Office of Research and Development (ORD) - National Health and Environmental Effects Research Laboratory (NHEERL) Corvallis OR publisher US Environmental Protection Agency originator Ecoregions denote areas of general similarity in ecosystems and in the type, quality, and quantity of environmental resources. They are designed to serve as a spatial framework for the research, assessment, management, and monitoring of ecosystems and ecosystem components. These general purpose regions are critical for structuring and implementing ecosystem management strategies across federal agencies, state agencies, and nongovernment organizations that are responsible for different types of resources within the same geographical areas. The approach used to compile this map is based on the premise that ecological regions can be identified through the analysis of patterns of biotic and abiotic phenomena, including geology, physiography, vegetation, climate, soils, land use, wildlife, and hydrology. The relative importance of each characteristic varies from one ecological region to another. A Roman numeral hierarchical scheme has been adopted for different levels for ecological regions. Level I is the coarsest level, dividing North America into 15 ecological regions. Level II divides the continent into 50 regions (Commission for Environmental Cooperation Working Group, 1997). At Level III, the continental United States contains 105 regions whereas the conterminous United States has 85 (U.S. Environmental Protection Agency, 2005). Level IV ecoregions are further subdivisions of Level III ecoregions. Methods used to define the ecoregions are explained in Omernik (1995, 2004), Omernik and others (2000), and Gallant and others (1989). Literature cited: Commission for Environmental Cooperation Working Group, 1997, Ecological regions of North America- toward a common perspective: Montreal, Commission for Environmental Cooperation, 71 p. Gallant, A. L., Whittier, T.R., Larsen, D.P., Omernik, J.M., and Hughes, R.M., 1989, Regionalization as a tool for managing environmental resources: Corvallis, Oregon, U.S. Environmental Protection Agency, EPA/600/3-89/060, 152p. Omernik, J.M., 1995, Ecoregions - a framework for environmental management, in Davis, W.S. and Simon, T.P., eds., Biological assessment and criteria-tools for water resource planning and decision making: Boca Raton, Florida, Lewis Publishers, p.49-62. Omernik, J.M., Chapman, S.S., Lillie, R.A., and Dumke, R.T., 2000, Ecoregions of Wisconsin: Transactions of the Wisconsin Academy of Science, Arts, and Letters, v. 88, p. 77-103. Omernik, J.M., 2004, Perspectives on the nature and definitions of ecological regions: Environmental Management, v. 34, Supplement 1, p. s27-s38. U.S. Environmental Protection Agency. 2013. Level III and IV ecoregions of the continental United States. U.S. EPA, National Health and Environmental Effects Research Laboratory, Corvallis, Oregon, Map scale 1:3,000,000. Available online at: https://www.epa.gov/eco-research/level-iii-and-iv-ecoregions-continental-united-states. Comments and questions regarding the Level III and IV Ecoregions should be addressed to Glenn Griffith, USGS, c/o US EPA., 200 SW 35th Street, Corvallis, OR 97333, (541)-754-4465, email:griffith.glenn@epa.gov Alternate: James Omernik, USGS, c/o US EPA, 200 SW 35th Street, Corvallis, OR 97333, (541)-754-4458, email:omernik.james@epa.gov Ecoregion maps assist managers of aquatic and terrestrial resources to understand the regional patterns of the realistically attainable quality of these resources. underDevelopment Marc Weber U.S. Environmental Protection Agency, Office of Water Geographer (541) 754-4491 200 S.W. 35th Street Corvallis OR 97333 weber.marc@epa.gov https://www.epa.gov/aboutepa/about-office-water pointOfContact asNeeded National Geospatial Data Asset Biodiversity and Ecosystems Theme NGDA NGDAID7 theme NGDA Portfolio Themes Biology Conservation Ecology Ecosystem Land Natural Resources theme EPA GIS Keyword Thesaurus United States place None https://edg.epa.gov/EPA_Data_License.htm otherRestrictions Use Constraints: None. Please check sources, scale, accuracy, currentness and other available information. Please confirm that you are using the most recent copy of both data and metadata. Acknowledgement of the EPA would be appreciated. otherRestrictions Access Constraints: None. PUBLIC http://project-open-data.github.io/schema/#accessLevel Standard Technical Controls vector eng; USA boundaries environment location -127.886770 -65.345754 22.896808 51.604869 2013-04-16 This file differs from the previous file in that Arizona ecoregions were updated. The previous minor topologic repairs and merging of a coastal waterbody are retained. The fields ending with "KEY" are linked to style and layer files containing color definitions for each level. They are also useful for map legends. L3_KEY pertains to Ecoregions of the Continental United States, whereas L2_KEY and L1_Key relate to North American designations within the United States. Except for the Great Lakes, waterbodies were merged with surrounding ecoregion polygons, especially along coastlines. Previously, field called NA_L3NAME was added to be consistent with the North America data. Ecoregions were digitized at 1:250,000 scale and are intended for large geographic extents (i.e. states, multiple counties, or river basins). Use for smaller areas, such as individual counties or a 1:24,000 scale map boundary, is not recommended. true Entity and Attribute Information Entity and Attribute Overview: Ecoregions are hierarchical, with Level IV being the most detailed and Level I defining the broadest classifications. Because of this hierarchy, Level IV features include appropriate codes and names for Levels III, II, and I. Likewise, Level III features contain Levels II and I, and Level II retains Level I information. Attributes pertaining to Level IV are only available for the Conterminous United States (US_). Level III has attributes for the US and North America (NA_) while Levels II and I apply to only North America. All features are identified by State and EPA Administrative Regions, as well. Fields ending with "KEY" combine ecoregion code and name attributes for convenient legends and are linked to style and layer files containing color definitions. Entity and Attribute Detail Citation: U.S. Environmental Protection Agency. 2011. Level III ecoregions of the conterminous United States. U.S. EPA, National Health and Environmental Effects Research Laboratory, Corvallis, Oregon, Map scale 1:3,000,000 Marc Weber U.S. Environmental Protection Agency, Office of Water Geographer (541) 754-4491 200 S.W. 35th Street Corvallis OR 97333 weber.marc@epa.gov https://www.epa.gov/aboutepa/about-office-water distributor https://dmap-prod-oms-edc.s3.us-east-1.amazonaws.com/ORD/Ecoregions/us/us_eco_l3.zip download Download The URL providing direct access to the downloadable dataset. download dataset Horizontal Positional Accuracy Report Data were collected using methods that have unknown accuracy (EPA National Geospatial Data Policy [NGDP] Accuracy Tier 10). For more information, please see EPA's NGDP at https://www.epa.gov/geospatial/epa-national-geospatial-data-policy) Level IV ecoregions are complete as of April 2013 but may be subject to change in the future.Ecoregions were digitized at 1:250,000 scale and are intended for large geographic extents (i.e. states, multiple counties, or river basins). Use for smaller areas, such as individual counties or a 1:24,000 scale map boundary, is not recommended. Level IV ecoregions are complete as of April 2013 but may be subject to change in the future.Ecoregions were digitized at 1:250,000 scale and are intended for large geographic extents (i.e. states, multiple counties, or river basins). Use for smaller areas, such as individual counties or a 1:24,000 scale map boundary, is not recommended. Although ecoregion polygons and attributes have been checked for accuracy, some errors may remain. Polygons along state borders were reviewed and updated, May 2010. ARC/INFO software is used to create and maintain topological relationships. This lineage was generated by the FGDC CSDGM to 19139 transformation 1) U.S.G.S. 1:250,000 topographic maps are used to delineate the ecoregions. The lines drawn are manually digitized or scanned to produce georeferenced electronic files. 2011-01-01T00:00:00 2) All base maps are joined together and errors along the edges are resolved. 2011-01-01T00:00:00 3) Topology is established and the maps are reviewed for accuracy, completeness, and conformity with the original lines. Corrections are made as needed and topology regenerated. 2011-01-01T00:00:00 4) Attributes are added. 2011-01-01T00:00:00 5) Maps are plotted for visual inspection by two individuals and necessary changes made. 2011-01-01T00:00:00 6) Ecoregions from all available states are merged and dissolved to identify and correct inconsistencies. 2011-01-01T00:00:00 7) Polygons of the corrected seamless ecoregion features are extended beyond the coastal borders. 2011-01-01T00:00:00 8) State and Ecoregion datasets are intersected. 2011-01-01T00:00:00 9) Topology errors removed. 2011-01-01T00:00:00 10) Final QA 2011-01-01T00:00:00 11) Updated Arizona Level III and IV ecoregion polygons, incorporated into U.S. map, checked topology, revised metadata. 2013-01-01T00:00:00 unknown 2017-04-16 This metadata was automatically generated from the FGDC Content Standard for Digital Geospatial Metadata standard (version FGDC-STD-001-1998) using the 2024-02-09T11:11:00 version of the FGDC CSDGM to ISO 19139 transform. Marc Weber U.S. Environmental Protection Agency, Office of Water Geographer (541) 754-4491 200 S.W. 35th Street Corvallis OR 97333 weber.marc@epa.gov https://www.epa.gov/aboutepa/about-office-water pointOfContact