Spatial Coverage
- Claiborne County (Tenn.)1
- Clarke County1
- Clay County (Ky.)1
- Colorado.1
- Culpeper Basin1
- Culpeper Basin (Va. and Md.)1
- Currituck County1
- Delaware Bay Region (Del. and N.J.)1
- Dickenson County (Va.)1
- Dinwiddie County (Va.)1
- Dismal Swamp Canal (N.C. and Va.)1
- District of Columbia1
- Dorchester County1
- Elizabeth River.1
- Elk Island (Va.)1
- Essex County (Va.)1
- Estillville Region (Tenn.)1
- Falls Church1
- Farmville Region (Va.)1
- Floyd (Ky.)1
