NPDES permits in Maryland
118 permits held by publicly owned wastewater treatment plants · issued by MDE
Effective
89
Administratively continued
6
Expired
23
Total tracked
118
Maryland Department of the Environment (MDE) runs the NPDES program in Maryland under delegation from EPA Region 3, issuing and enforcing the discharge permits listed here. Klarifi tracks 118 permits held by publicly owned treatment plants in the state, with status, expiry, design flow and three-year compliance for each. Agency website →
An NPDES permit runs for five years. To keep discharging, a plant must apply for renewal at least 180 days before the expiry date, and the renewed permit usually arrives with tighter effluent limits, new monitoring requirements or a compliance schedule. That is why the year a permit expires is the year a plant starts budgeting for upgrades: nutrient removal, disinfection, capacity or controls.
Permit renewals by year
2029: 10 permits
2030: 40 permits
2031: 18 permits
Largest permit holders in Maryland
| Facility | City | Avg flow (MGD) | Design (MGD) | NPDES permit | Status | Expires | Violations (3y) |
|---|---|---|---|---|---|---|---|
| Back River Wastewater Treatment Plant | Baltimore | 114.1 | — | MDL021555 | Effective | Dec 2030 | 32 |
| Patapsco Wastewater Treatment Plant | Baltimore | 49.01 | — | MDL021601 | Effective | Dec 2030 | 22 |
| Little Patuxent Water Reclamation Plant | Savage | 16.68 | 25 | MD0055174 | Effective | May 2031 | 8 |
| Piscataway Swge Plnt | Accokeek | 19.79 | — | MDL021539 | Effective | Dec 2030 | 25 |
| Annapolis WRF | Annapolis | 8.48 | 13 | MD0021814 | Effective | Jan 2030 | 6 |
| Sod Run Wastewater Treatment Plant | Perryman | 10.81 | — | MDL056545 | Effective | Dec 2030 | 0 |
| City Of Frederick Wastewater Treatment Plant-2012 | Frederick | 5.4 | 8 | MD0021610 | Effective | May 2031 | 23 |
| Ballenger-Mckinney WWTP | Frederick | 6.92 | 7 | MD0021822 | Effective | Dec 2030 | 1 |
| Parkway Wastewater Treatment Plant | Laurel | 6.35 | — | MDL021725 | Effective | Dec 2030 | 2 |
| Ocean City Wastewater Treatment Plant | Ocean City | 5.88 | — | MDL020044 | Effective | Dec 2030 | 2 |
| City Of Salisbury Wastewater Treatment Plant | Salisbury | 5.05 | — | MDL021571 | Effective | Dec 2030 | 83 |
| Westminster WWTP | Westminster | 3.41 | 5 | MD0021831 | Effective | Jul 2031 | 9 |
| Conococheague WWTP | Williamsport | 1.84 | 4.1 | MD0063509 | Effective | May 2031 | 0 |
| Broadneck Water Reclamation Facility | Annapolis | 3.68 | — | MDL021644 | Effective | Dec 2030 | 106 |
| Freedom District WWTP | Sykesville | 1.97 | 3.5 | MD0021512 | Effective | Oct 2029 | 32 |
| Easton WWTP | Easton | 2.02 | — | MDL020273 | Effective | Dec 2030 | 2 |
| Maryland City Water Reclamation Facility | Laurel | 1.53 | — | MDL062596 | Effective | Dec 2030 | 27 |
| Wssc Damascus WRRF | Gaithersburg | 0.72 | 1.5 | MD0020982 | Effective | Dec 2028 | 3 |
| Pocomoke City Wastewater Treatment Facility | Pocomoke City | 0.52 | 1.4 | MD0022551 | Effective | May 2028 | 0 |
| The City Of Bowie (ssos) | Bowie | 1.4 | — | MDL021628 | Effective | Dec 2030 | 8 |
| Northeast River Advanced WWTP | Charlestown | 1.25 | — | MDL052027 | Effective | Dec 2030 | 38 |
| Mount Airy WWTP | Mount Airy | 0.69 | 1.2 | MD0022527 | Expired | Dec 2025 | 142 |
| Taneytown Wastewater Treatment Plant | Taneytown | 0.51 | 1.1 | MD0020672 | Effective | May 2031 | 3 |
| Town Of La Plata | La Plata | 1.04 | — | MDL020524 | Effective | Dec 2030 | 111 |
| Chestertown WWTP | Chestertown | 0.63 | 0.9 | MD0020010 | Effective | Sep 2026 | 5 |
NPDES permits in Maryland: questions
Sources and methodology
Flow, permit and violation figures come from the EPA's ICIS-NPDES discharge monitoring records. Population served comes from the Clean Watersheds Needs Survey 2022. Treatment structures are identified by Klarifi's review of aerial imagery, and capital improvement projects are extracted from published municipal budget documents. Violations are counted over the last three years of monitoring reports.
Data refreshed September 11, 2026.