St. Marys County contains 91 EPA-regulated facilities, 18 of which are currently flagged for significant noncompliance. The county also hosts 0 Superfund sites and 1 TRI chemical reporters. EPA has assessed $12.6k in lifetime penalties and TRI reporters disclosed roughly 1 lb of on-site releases. That facility count is near the Maryland state average of 74 per county.
| Facility | City | On-site (lb) | Status |
|---|---|---|---|
| Naval Air Station Patuxent River | Patuxent River | 1 | Compliant |
| Facility | City | Penalties | Last Inspected |
|---|---|---|---|
| Golden Eye Seafood | Piney Point | $2.6k | 2019-11-21 |
| Edward Sloan Mine | Mechanicsville | $0 | |
| Burch's Pit | Leonardtown | $0 | 2011-06-23 |
| Hollywood Rmc Facility | Hollywood | $0 | |
| Tall Timbers Development Company | Tall Timbers | $0 | 2025-03-06 |
| Wildewood Apartments, Phase I | California | $0 | |
| Cape St. Mary's Marina, Inc | Mechanicsville | $0 | 2025-10-06 |
| Charlotte Hall Metal & Scrap Llc | Charlotte Hall | $0 | 2026-03-04 |
| C. A. Bean, Inc. | Mechanicsville | $0 | 2022-06-21 |
| Wildewood Apartment Homes, Phase Ii | California | $0 | |
| Mattingly Mine | Leonardtown | $0 | |
| Camp Maria Retreat Center | Leonardtown | $0 | |
| Carruth & Son, Inc. - Lexington Park | Lexington Park | $0 | 2019-04-24 |
| Hollywood Used Auto Parts | Hollywood | $0 | |
| Leonard's Grant H.o.a. | Leonardtown | $0 | |
| Point Lookout Marina | Ridge | $0 | |
| Chancellor's Point State Park | St Mary's City | $0 | 2019-01-24 |
| Maryland Seafood, Inc. | Valley Lee | $0 | 2017-02-08 |