0 100 200 300 400 Mi 0 200 400 600 Km Scale 1:7,500,000 Albers Equal Area Projection 101

104103 102

105 106 106 107 108
104 109110

111 112 113 113 116117 118 119
120 115

114 0 100 200 300 400 Mi 0 200 400 600 Km Scale 1:16,000,000 Albers Equal Area Projection 

### 101. Arctic Coastal Plain 102. Arctic Foothills 103. Brooks Range 104. Interior Forested Lowlands and Uplands 105. Interior Highlands 106. Interior Bottomlands 107. Yukon Flats 108. Ogilvie Mountains 109. Subarctic Coastal Plains 110. Seward Peninsula 111. Ahklun and Kilbuck Mountains 112. Bristol Bay-Nushagak Lowlands 113. Alaska Peninsula Mountains 114. Aleutian Islands (Western portion not shown) 115. Cook Inlet 116. Alaska Range 117. Copper Plateau 118. Wrangell Mountains 119. Pacific Coastal Mountains 120. Coastal Western Hemlock-Sitka Spruce Forests CANADA Albany

Annapolis

Atlanta Augusta

Austin Baton Rouge Bismarck
Boise Boston

Carson City

Charleston Cheyenne

Columbia Columbus Concord

Denver Des Moines Dover

Frankfort Harrisburg Hartford Helena

Indianapolis

Jackson Jefferson City Lansing

Lincoln

Little Rock Madison

Montgomery Montpelier

Nashville Oklahoma City Olympia

Phoenix Pierre Providence

Raleigh Richmond Sacramento Saint Paul Salem

Salt Lake City

Santa Fe Springfield

Tallahassee Topeka Trenton

Juneau Akron

Albuquerque Birmingham Buffalo

Charlotte Chicago

Cincinnati Cleveland

Colorado Springs

Corpus Christi Dallas Detroit

El Paso Fort Worth Fresno

Houston Jacksonville Lexington

Los Angeles Louisville

Memphis

Miami

Milwaukee Minneapolis

Mobile New Orleans New York Newark Omaha Philadelphia Pittsburgh Portland

Rochester

San Antonio San Diego San Francisco San Jose

Santa Ana

Seattle

Shreveport

Tampa Toledo

Tucson Tulsa Wichita Baltimore

Saint Louis

Mesa Washington DC Kansas City Norfolk


### 85 858 14 67 5 4 78 9 1 4 3 10 11 1 2 77 77 

### 15 10

### 16 12 80
13

81 79 23 23 

### 20 19 18 17 17 17 17 

### 41
17 

### 42
43 17 17 

### 17

21

23 22 23 23 23 23 

### 23 24 25
3031 34 32



### 33 32 29 25 

### 26 25 42 46
44
27 28 40 39 38 37 36
35 40 47 52 50 51 49 48
50 51 

### 53
54 57 56 55 72 7168
7374
75 

### 65 57 61 62

69 6766 

### 70

66

75 76 63 65 45 63 63 646284 84 

### 8360 58 58 58
58 

### 59 82

84 59 69 

### 1

30 59 

# Level III Ecoregions of the Continental United States (Revised April 2013) 

# National Health and Environmental Effects Research Laboratory U.S. Environmental Protection Agency

57. Huron/Erie Lake Plains 58. Northeastern Highlands 59. Northeastern Coastal Zone 60. Northern Allegheny Plateau 61. Erie Drift Plain 62. North Central Appalachians 63. Middle Atlantic Coastal Plain 64. Northern Piedmont 65. Southeastern Plains 66. Blue Ridge 67. Ridge and Valley 68. Southwestern Appalachians 69. Central Appalachians 70. Western Allegheny Plateau 71. Interior Plateau 72. Interior River Valleys and Hills 73. Mississippi Alluvial Plain 74. Mississippi Valley Loess Plains 75. Southern Coastal Plain 76. Southern Florida Coastal Plain 77. North Cascades 78. Klamath Mountains/California High North Coast Range 79. Madrean Archipelago 80. Northern Basin and Range 81. Sonoran Basin and Range 82. Acadian Plains and Hills 83. Eastern Great Lakes Lowlands 84. Atlantic Coastal Pine Barrens 85. Southern California/Northern Baja Coast 1. Coast Range 2. Puget Lowland 3. Willamette Valley 4. Cascades 5. Sierra Nevada 6. Central California Foothills and Coastal Mountains 7. Central California Valley 8. Southern California Mountains 9. Eastern Cascades Slopes and Foothills 10. Columbia Plateau 11. Blue Mountains 12. Snake River Plain 13. Central Basin and Range 14. Mojave Basin and Range 15. Northern Rockies 16. Idaho Batholith 17. Middle Rockies 18. Wyoming Basin 19. Wasatch and Uinta Mountains 20. Colorado Plateaus 21. Southern Rockies 22. Arizona/New Mexico Plateau 23. Arizona/New Mexico Mountains 24. Chihuahuan Deserts 25. High Plains 26. Southwestern Tablelands 27. Central Great Plains 28. Flint Hills 29. Cross Timbers 30. Edwards Plateau 31. Southern Texas Plains 32. Texas Blackland Prairies 33. East Central Texas Plains 34. Western Gulf Coastal Plain 35. South Central Plains 36. Ouachita Mountains 37. Arkansas Valley 38. Boston Mountains 39. Ozark Highlands 40. Central Irregular Plains 41. Canadian Rockies 42. Northwestern Glaciated Plains 43. Northwestern Great Plains 44. Nebraska Sand Hills 45. Piedmont 46. Northern Glaciated Plains 47. Western Corn Belt Plains 48. Lake Agassiz Plain 49. Northern Minnesota Wetlands 50. Northern Lakes and Forests 51. North Central Hardwood Forests 52. Driftless Area 53. Southeastern Wisconsin Till Plains 54. Central Corn Belt Plains 55. Eastern Corn Belt Plains 56. Southern Michigan/Northern Indiana Drift Plains

The ecoregions shown here have been derived from Omernik (1987) and from refinements of the U.S. EPA ecoregion framework made in numerous state-level projects. These projects, conducted in collaboration with the U.S. EPA regional offices, state resource management agencies, and with other federal agencies, typically involved refining ecoregions, defining subregions, and locating sets of stream reference sites. Designed to serve as a spatial framework for environmental resource management, ecoregions denote areas within which ecosystems (and the type, quality, and quantity of environmental resources) are generally similar. The ecoregions have been used to develop regional biological criteria and water quality standards and to set management goals for nonpoint source pollution, among other applications. The approach used to compile this map is based on the premise that ecological regions can be identified through the analysis of the patterns and the composition of biotic and abiotic phenomena that affect or reflect differences in ecosystem quality and integrity (Omernik 1987, 1995). These phenomena include geology, physiography, vegetation, climate, soils, land use, wildlife, and hydrology. The relative importance of each characteristic varies from one ecological region to another regardless of the hierarchical level. A Roman numeral classification scheme has been adopted for different levels of ecological regions. Level I is the coarsest level, dividing North America into 15 ecological regions, whereas at Level II the continent is subdivided into 50 classes (CEC 1997, 2006). Level III is the hierarchical level shown on this map, with 105 ecoregions in the continental U.S. For the conterminous United States, the ecoregions have been further subdivided to 968 Level IV ecoregions. Details about the ecoregions or their applications are explained in reports and publications from the state and regional projects (e.g., Bryce et al., 1998, 2003; Chapman et al., 2001, 2006; Gallant et al., 1989, 1995; Griffith et al., 2002, 2004, 2009; McGrath et al., 2002; Omernik et al., 2000, 2004; Thorson et al., 2003; Wiken et al., 2011; and Woods et al., 1996, 2002, 2004). For additional information, contact James M. Omernik, USGS, c/o U.S. EPA, 200 SW 35th Street, Corvallis, OR 97333, phone (541) 754-4458, email omernik.james@epa.gov; or Glenn Griffith, USGS, c/o US EPA, 200 SW 35th Street, Corvallis, OR 97333, phone (541) 754-4465, email ggriffith@usgs.gov. REFERENCES CITED Bryce, S.A., J.M. Omernik, D.E. Pater, M. Ulmer, J. Schaar, J. Freeouf, R. Johnson, P. Kuck, and S.H. Azevedo. 1998. Ecoregions

of North Dakota and South Dakota. (map poster). U.S. Geological Survey, Reston, VA. Scale 1:1,500,000. Bryce, S.A., A.J. Woods, J.D. Morefield, J.M. Omernik, T.R. McKay, G.K. Brackley, R.K. Hall, D.K. Higgins, D.C. McMorran,

K.E. Vargas, E.B. Petersen, D.C. Zamudio, and J.A. Comstock. 2003. Ecoregions of Nevada. (map poster). U.S. Geological Survey, Reston, VA. Scale 1:1,350,000. Chapman, S.S., G.E. Griffith, J.M. Omernik, A.B. Price, J. Freeouf, and D.L. Schrupp. 2006. Ecoregions of Colorado. (map

poster). U.S. Geological Survey, Reston, VA. Scale 1:1,200,000. Chapman, S.S., J.M. Omernik, J.A. Freeouf, D.G. Huggins, J.R. McCauley, C.C. Freeman, G. Steinauer, R.T. Angelo, and R.L.

Schlepp. 2001. Ecoregions of Nebraska and Kansas (map poster): U.S. Geological Survey, Reston, VA. Scale 1:1,950,000. Commission for Environmental Cooperation. 1997. Ecological regions of North America: toward a common perspective.

Commission for Environmental Cooperation, Montreal, Quebec, Canada. 71 p. Map (scale 1:12,500,000). Commission for Environmental Cooperation. 2006. Ecological regions of North America – Levels I, II, and III: Montreal, Quebec, Canada, Commission for Environmental Cooperation, scale 1:10,000,000, http://www.epa.gov/wed/pages/ecoregions/na_eco.htm. Gallant, A.L., T.R. Whittier, D.P. Larsen, J.M. Omernik, and R.M. Hughes. 1989. Regionalization as a tool for managing

environmental resources. EPA/600/3-89/060. U.S. Environmental Protection Agency, Environmental Research Laboratory, Corvallis, OR. 152 p. Gallant, A.L., E.F. Binnian, J.M. Omernik, and M.B. Shasby. 1995. Ecoregions of Alaska. U.S. Geological Survey Professional

Paper 1567. U.S. Government Printing Office, Washington D.C. 73 p. Griffith, G.E., S.A. Bryce, J.M. Omernik, J.A. Comstock, A.C. Rogers, B. Harrison, S.L. Hatch, and D. Bezanson. 2004. Ecoregions of

Texas. (map poster). U.S. Geological Survey, Reston, VA. Scale 1:2,500,000. Griffith, G.E., J.M. Omernik, S.A. Bryce, J. Royte, W.D. Hoar, J.W. Homer, D. Keirstead, K.J. Metzler, and G. Hellyer. 2009. Ecoregions

of New England (2 sided color poster with map, descriptive text, summary tables, and photographs). U.S. Geological Survey, Reston, VA. Scale 1:1,325,000. Griffith, G.E., J.M. Omernik, J.A. Comstock, M.P. Shafale, W.H. McNab, D.R. Lenat, J.B. Glover, and V.B. Shelburne. 2002.

Ecoregions of North Carolina and South Carolina. (map poster). U.S. Geological Survey, Reston, VA. Scale 1:1,500,000. McGrath, C.L., A.J. Woods, J.M. Omernik, S.A. Bryce, M. Edmondson, J.A. Nesser, J. Shelden, R.C. Crawford, J.A. Comstock, and

M.D. Plocher. 2002. Ecoregions of Idaho. (map poster). U.S. Geological Survey, Reston, VA. Scale 1:1,350,000. Omernik, J.M. 1987. Ecoregions of the conterminous United States. Map (scale 1:7,500,000). Annals of the Association of American

Geographers 77(1):118-125. Omernik, J.M. 1995. Ecoregions: A spatial framework for environmental management. In: Biological Assessment and Criteria: Tools

for Water Resource Planning and Decision Making. Davis, W.S. and T.P. Simon (eds.) Lewis Publishers, Boca Raton, FL. Pp. 49-62. Omernik, J.M. 2004. Perspectives on the nature and definition of ecological regions. Environmental Management 34 (Suppl. 1): S27-S38. Omernik, J.M., S.S. Chapman, R.A. Lillie, and R.T. Dumke. 2000. Ecoregions of Wisconsin. Transactions of the Wisconsin

Acadamy of Sciences, Arts, and Letters 88:77-103. Thorson, T.D., S.A. Bryce, D.A. Lammers, A.J. Woods, J.M. Omernik, J. Kagan, D.E. Pater, and J.A. Comstock. 2003. Ecoregions of

Oregon. (map poster). U.S. Geological Survey, Reston, VA. Scale 1:1,350,000. Wiken, E., Jiménez Nava, F., and Griffith, G. 2011. North American Terrestrial Ecoregions - Level III. Commission for Environmental

Cooperation, Montreal, Canada. 149 p., ftp://ftp.epa.gov/wed/ecoregions/pubs/NA_TerrestrialEcoregionsLevel3_Final-2june11_CEC.pdf. Woods, A.J., T.L. Foti, Chapman, S.S., J.M. Omernik, J. Wise, E.O. Murray, W.L. Prior, J. Pagan, J.A. Comstock, and M. Radford.

2004. Ecoregions of Arkansas. (map poster). U.S. Geological Survey, Reston, VA. Scale 1:1,000,000. Woods, A.J., J.M. Omernik, D.D. Brown, and C.W. Kiilsgaard. 1996. Level III and IV ecoregions of Pennsylvania and the Blue

Ridge Mountains, the Ridge and Valley, and Central Appalachians of Virginia, West Virginia, and Maryland. EPA/600/R-96/077. U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Corvallis, OR. 50 p. Woods, A.J., J.M. Omernik, W.H. Martin, G.J. Pond, W.M. Andrews, S.M. Call, J.A. Comstock, and D.D. Taylor. 2002. Ecoregions

of Kentucky. (map poster). U.S. Geological Survey, Reston, VA. Scale 1:1,000,000. CITING THIS MAP: U.S. Environmental Protection Agency, 2013, Level III ecoregions of the continental United States: Corvallis, Oregon, U.S. EPA – National Health and Environmental Effects Research Laboratory, map scale 1:7,500,000, http://www.epa.gov/wed/pages/ecoregions/level_iii_iv.htm.