Region
- South Carolina6
- California, Southern5
- New Jersey5
- North Carolina5
- Black Creek Aquifer (S.C. and N.C.)4
- Colorado4
- Columbia Plateau4
- Hudson River Watershed4
- MontanaFort Peck Indian Reservation4
- MontanaNorthern Cheyenne Indian Reservation4
- Black Hills (S.D. and Wyo.)3
- California, Northern3
- Delaware3
- FloridaHillsborough County3
- FloridaMiami-Dade County3
- High Plains (U.S.)3
- Idaho3
- Judith River Formation3
- Lakota Formation3
- MontanaBig Horn County3