<?xml version="1.0" encoding="UTF-8"?>
<metadata>
	<idinfo>
		<keywords>
			<theme>
				<themekt>ISO 19115 Topic Category</themekt>
				<themekey>biota</themekey>
				<themekey>boundaries</themekey>
				<themekey>environment</themekey>
				<themekey>location</themekey>
			</theme>
			<theme>
				<themekt>EPA GIS Keyword Thesaurus</themekt>
				<themekey>Biology</themekey>
				<themekey>Conservation</themekey>
				<themekey>Ecology</themekey>
				<themekey>Ecosystem</themekey>
				<themekey>Land</themekey>
				<themekey>Natural Resources</themekey>
			</theme>
			<place>
				<placekt>None</placekt>
				<placekey>United States</placekey>
			</place>
		</keywords>
		<citation>
			<citeinfo>
				<origin>US Environmental Protection Agency</origin>
				<title>Level III Ecoregions of the Conterminous United States</title>
				<pubinfo>
					<publish>U.S. EPA Office of Research and Development (ORD) - National Health and Environmental Effects Research Laboratory (NHEERL) </publish>
					<pubplace>Corvallis, OR</pubplace>
				</pubinfo>
				<pubdate>20130416</pubdate>
				<onlink>ftp://ftp.epa.gov/wed/ecoregions/us/usl3_no_st.zip</onlink>
				<onlink>http://edg.epa.gov</onlink>
			</citeinfo>
		</citation>
		<descript>
			<abstract>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: http://www.epa.gov/wed/pages/ecoregions/level_iii_iv.htm.

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</abstract>
			<purpose>Ecoregion maps assist managers of aquatic and terrestrial resources to understand the regional patterns of the realistically attainable quality of these resources.</purpose>
			<supplinf>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.</supplinf>
		</descript>
		<timeperd>
			<current>Publication date</current>
			<timeinfo>
				<sngdate>
					<caldate>20130416</caldate>
				</sngdate>
			</timeinfo>
		</timeperd>
		<status>
			<progress>In work</progress>
			<update>As needed</update>
		</status>
		<accconst>None.</accconst>
		<useconst>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.</useconst>
		<spdom>
			<bounding>
				<westbc>-127.886770</westbc>
				<eastbc>-65.345754</eastbc>
				<northbc>51.604869</northbc>
				<southbc>22.896808</southbc>
			</bounding>
		</spdom>
		<secinfo>
			<secsys>FIPS Pub 199</secsys>
			<secclass>No Confidentiality</secclass>
			<sechandl>Standard Technical Controls</sechandl>
		</secinfo>
		<ptcontac>
			<cntinfo>
				<cntperp>
					<cntorg>U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory (NHEERL)</cntorg>
					<cntper>Marc Weber</cntper>
				</cntperp>
				<cntpos>GIS Analyst</cntpos>
				<cntaddr>
					<addrtype>mailing address</addrtype>
					<address>200 S.W. 35th Street</address>
					<city>Corvallis</city>
					<state>OR</state>
					<postal>97333</postal>
				</cntaddr>
				<cntvoice>(541) 754-4469</cntvoice>
				<cntemail>weber.marc@epa.gov</cntemail>
				<cntinst>http://www.epa.gov/nheerl/</cntinst>
			</cntinfo>
		</ptcontac>
	</idinfo>
	<dataqual>
		<logic>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.</logic>
		<complete>  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.</complete>
		<posacc>
			<horizpa>
				<horizpar>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 http://epa.gov/geospatial/policies.html)</horizpar>
			</horizpa>
		</posacc>
		<lineage>
			<procstep>
				<procdate>2011</procdate>
				<procdesc>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.</procdesc>
			</procstep>
			<procstep>
				<procdate>2011</procdate>
				<procdesc>2) All base maps are joined together and errors along the edges are resolved.</procdesc>
			</procstep>
			<procstep>
				<procdate>2011</procdate>
				<procdesc>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.</procdesc>
			</procstep>
			<procstep>
				<procdate>2011</procdate>
				<procdesc>4) Attributes are added.</procdesc>
			</procstep>
			<procstep>
				<procdate>2011</procdate>
				<procdesc>5) Maps are plotted for visual inspection by two individuals and necessary changes made.</procdesc>
			</procstep>
			<procstep>
				<procdate>2011</procdate>
				<procdesc>6) Ecoregions from all available states are merged and dissolved to identify and correct inconsistencies.</procdesc>
			</procstep>
			<procstep>
				<procdate>2011</procdate>
				<procdesc>7) Polygons of the corrected seamless ecoregion features are extended beyond the coastal borders.</procdesc>
			</procstep>
			<procstep>
				<procdate>2011</procdate>
				<procdesc>8) State and Ecoregion datasets are intersected.</procdesc>
			</procstep>
			<procstep>
				<procdate>2011</procdate>
				<procdesc>9) Topology errors removed.</procdesc>
			</procstep>
			<procstep>
				<procdate>2011</procdate>
				<procdesc>10) Final QA</procdesc>
			</procstep>
			<procstep>
				<procdate>2013</procdate>
				<procdesc>11) Updated Arizona Level III and IV ecoregion polygons, incorporated into U.S. map, checked topology, revised metadata.</procdesc>
			</procstep>
		</lineage>
	</dataqual>
	<spdoinfo>
		<direct>Vector</direct>
		<ptvctinf>
			<sdtsterm>
				<sdtstype>GT-polygon composed of chains</sdtstype>
				<ptvctcnt>1253</ptvctcnt>
			</sdtsterm>
		</ptvctinf>
	</spdoinfo>
	<spref>
		<horizsys>
			<planar>
				<mapproj>
					<mapprojn>USA Contiguous Albers Equal Area Conic USGS version</mapprojn>
					<albers>
						<stdparll>29.5</stdparll>
						<stdparll>45.5</stdparll>
						<longcm>-96.0</longcm>
						<latprjo>23.0</latprjo>
						<feast>0.0</feast>
						<fnorth>0.0</fnorth>
					</albers>
				</mapproj>
				<planci>
					<plance>coordinate pair</plance>
					<coordrep>
						<absres>0.0000000037527980722984474</absres>
						<ordres>0.0000000037527980722984474</ordres>
					</coordrep>
					<plandu>Meter</plandu>
				</planci>
			</planar>
			<geodetic>
				<horizdn>D North American 1983</horizdn>
				<ellips>GRS 1980</ellips>
				<semiaxis>6378137.0</semiaxis>
				<denflat>298.257222101</denflat>
			</geodetic>
		</horizsys>
	</spref>
	<eainfo>
		<detailed>
			<enttyp>
				<enttypl>usl3_no_st</enttypl>
				<enttypd>shapefile name</enttypd>
				<enttypds>US Environmental Protection Agency</enttypds>
			</enttyp>
			<attr>
				<attrlabl>FID</attrlabl>
				<attrdef>Internal feature number</attrdef>
				<attrdefs>esri</attrdefs>
				<attrdomv>
					<rdom>
						<rdommin>0</rdommin>
						<rdommax>1252</rdommax>
					</rdom>
					<udom>Sequential unique whole numbers that are automatically generated.</udom>
				</attrdomv>
			</attr>
			<attr>
				<attrlabl>Shape</attrlabl>
				<attrdef>Feature Geometry</attrdef>
				<attrdefs>esri</attrdefs>
				<attrdomv>
					<udom>defines feature type</udom>
				</attrdomv>
			</attr>
			<attr>
				<attrlabl>US_L3CODE</attrlabl>
				<attrdef>Code for Level III Ecoregion (US)</attrdef>
				<attrdefs>USEPA</attrdefs>
				<attrdomv>
					<udom>unique code</udom>
				</attrdomv>
			</attr>
			<attr>
				<attrlabl>US_L3NAME</attrlabl>
				<attrdef>Name for Level III Ecoregion (US)</attrdef>
				<attrdefs>USEPA</attrdefs>
				<attrdomv>
					<udom>unique name</udom>
				</attrdomv>
			</attr>
			<attr>
				<attrlabl>NA_L3CODE</attrlabl>
				<attrdef>Code for Level III Ecoregion (North America/CEC)</attrdef>
				<attrdefs>CEC</attrdefs>
				<attrdomv>
					<udom>unique code</udom>
				</attrdomv>
			</attr>
			<attr>
				<attrlabl>NA_L3NAME</attrlabl>
				<attrdef>Name for Level III Ecoregion (North America/CEC)</attrdef>
				<attrdefs>CEC</attrdefs>
				<attrdomv>
					<udom>unique name</udom>
				</attrdomv>
			</attr>
			<attr>
				<attrlabl>NA_L2CODE</attrlabl>
				<attrdef>Code for Level II Ecoregion (North America/CEC)</attrdef>
				<attrdefs>CEC</attrdefs>
				<attrdomv>
					<udom>unique code</udom>
				</attrdomv>
			</attr>
			<attr>
				<attrlabl>NA_L2NAME</attrlabl>
				<attrdef>Name for Level II Ecoregion (North America/CEC)</attrdef>
				<attrdefs>CEC</attrdefs>
				<attrdomv>
					<udom>unique name</udom>
				</attrdomv>
			</attr>
			<attr>
				<attrlabl>NA_L1CODE</attrlabl>
				<attrdef>Code for Level I Ecoregion (North America/CEC)</attrdef>
				<attrdefs>CEC</attrdefs>
				<attrdomv>
					<udom>unique code</udom>
				</attrdomv>
			</attr>
			<attr>
				<attrlabl>NA_L1NAME</attrlabl>
				<attrdef>Name for Level I Ecoregion (North America/CEC)</attrdef>
				<attrdefs>CEC</attrdefs>
				<attrdomv>
					<udom>unique name</udom>
				</attrdomv>
			</attr>
			<attr>
				<attrlabl>L3_KEY</attrlabl>
				<attrdef>US Level III Code and Name for Legend, color layer/style file</attrdef>
				<attrdefs>USEPA</attrdefs>
				<attrdomv>
					<udom>unique code plus name</udom>
				</attrdomv>
			</attr>
			<attr>
				<attrlabl>L2_KEY</attrlabl>
				<attrdef>NA Level II Code and Name for Legend, color layer/style file</attrdef>
				<attrdefs>USEPA</attrdefs>
				<attrdomv>
					<udom>unique code plus name</udom>
				</attrdomv>
			</attr>
			<attr>
				<attrlabl>L1_KEY</attrlabl>
				<attrdef>NA Level I Code and Name for Legend, color layer/style file</attrdef>
				<attrdefs>USEPA</attrdefs>
				<attrdomv>
					<udom>unique code plus name</udom>
				</attrdomv>
			</attr>
			<attr>
				<attrlabl>Shape_Leng</attrlabl>
			</attr>
			<attr>
				<attrlabl>Shape_Area</attrlabl>
				<attrdef>Area of feature in internal units squared.</attrdef>
				<attrdefs>Esri</attrdefs>
				<attrdomv>
					<udom>Positive real numbers that are automatically generated.</udom>
				</attrdomv>
			</attr>
		</detailed>
		<detailed>
			<enttyp>
				<enttypl>usl3_no_st.shp</enttypl>
				<enttypd>shapefile name</enttypd>
				<enttypds>US Environmental Protection Agency</enttypds>
			</enttyp>
		</detailed>
		<overview>
			<eaover>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.</eaover>
			<eadetcit>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</eadetcit>
		</overview>
	</eainfo>
	<distinfo>
		<resdesc>Downloadable Data</resdesc>
		<distliab>Although these data have been processed successfully on a computer system at the Environmental Protection Agency, no warranty expressed or implied is made regarding the accuracy or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. It is also strongly recommended that careful attention be paid to the contents of the metadata file associated with these data to evaluate data set limitations, restrictions or intended use. The U.S. Environmental Protection Agency shall not be held liable for improper or incorrect use of the data described and/or contained herein.</distliab>
		<distrib>
			<cntinfo>
				<cntperp>
					<cntorg>U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory (NHEERL)</cntorg>
					<cntper>Marc Weber</cntper>
				</cntperp>
				<cntpos>GIS Analyst</cntpos>
				<cntaddr>
					<addrtype>mailing address</addrtype>
					<address>200 S.W. 35th Street</address>
					<city>Corvallis</city>
					<state>OR</state>
					<postal>97333</postal>
				</cntaddr>
				<cntvoice>(541) 754-4469</cntvoice>
				<cntemail>weber.marc@epa.gov</cntemail>
				<cntinst>http://www.epa.gov/nheerl/</cntinst>
			</cntinfo>
		</distrib>
	</distinfo>
	<metainfo>
		<metd>20130416</metd>
		<metfrd>20170416</metfrd>
		<metstdn>FGDC Content Standard for Digital Geospatial Metadata</metstdn>
		<metstdv>FGDC-STD-001-1998</metstdv>
		<metc>
			<cntinfo>
				<cntperp>
					<cntorg>U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory (NHEERL)</cntorg>
					<cntper>Marc Weber</cntper>
				</cntperp>
				<cntpos>GIS Analyst</cntpos>
				<cntaddr>
					<addrtype>mailing address</addrtype>
					<address>200 S.W. 35th Street</address>
					<city>Corvallis</city>
					<state>OR</state>
					<postal>97333</postal>
				</cntaddr>
				<cntvoice>(541) 754-4469</cntvoice>
				<cntemail>weber.marc@epa.gov</cntemail>
				<cntinst>http://www.epa.gov/nheerl/</cntinst>
			</cntinfo>
		</metc>
	</metainfo>
	<Esri><CreaDate>20190117</CreaDate><CreaTime>16173800</CreaTime><ArcGISFormat>1.0</ArcGISFormat><SyncOnce>TRUE</SyncOnce></Esri></metadata>
