Region
Mississippi
4
Montana
4
Middle West
3
Appalachian Basin
2
California
2
Colorado
2
Inyo County
2
New Mexico
2
Oklahoma
2
Anadarko Basin
1
Arbuckle-Simpson Aquifer
1
Arbuckle-Simpson Aquifer (Okla.)
1
Arizona
1
Arkansas
1
Chickasaw National Recreation Area
1
Chickasaw National Recreation Area (Okla.)
1
Colfax County
1
Death Valley National Park (Calif. and Nev.)
1
Front Range (Colo. and Wyo.)
1
Garland County
1
Hot Spring County
1
Illinois Basin
1
Kansas
1
Malvern Quadrangle (Ark.)
1
Michigan Basin (Mich. and Ont.)
1
Missouri
1
Nevada
1
Nevada National Security Site
1
Socorro County
1
South Dakota
1
Torrance County
1
Utah
1
Valencia County
1
Wyoming
1
Yucca Flat Region
1