Maryland NPDES permit search
Status, expiry and violations for 118 municipal wastewater permits · issued by MDE
In short
How do I look up an NPDES permit in Maryland?
Search this page by permit number or plant name for a municipal plant’s permit status, expiry date and violations. For the official file, search MDE’s wastewater permit portal or the MDE Data Viewer. EPA’s ECHO database shows the monitoring results and violations of every permit. The 665 industrial permits in Maryland are listed in Klarifi with a free account.
Links to official sources checked September 2026.
Effective
93
Administratively continued
6
Expired
19
Plants with effluent violations, 3 years
78
Where to find official Maryland NPDES records
Maryland Department of the Environment (MDE) runs the NPDES program in Maryland under authorization from EPA Region 3. It issues and enforces the permits and keeps the official file: applications, permits, fact sheets and monitoring reports. MDE website ↗
permits · permit documents · applications
Enter part of the facility name, the NPDES number or the state number, or pick a county, and search (results can take half a minute); “More Info” lists the documents to download.
inspections · violations · enforcement
Under Water and Science Administration, choose WSA Compliance Inspections or WSA Enforcement Actions and search by site name or county.
permits · DMRs · inspections · violations · enforcement
EPA’s Enforcement and Compliance History Online. Search water facilities by permit number, name or city; the Detailed Facility Report lists inspections, violations and enforcement actions, and Effluent Charts plot monitoring results against the permit limits.
- Permit numbers
- Each permit has a state number such as 22-DP-0581, whose first two digits change at renewal, and an NPDES number in EPA’s format (MD0021555 for Back River).
- Discharge monitoring reports
- Through EPA’s NetDMR.
- Violations and enforcement
- MDE’s formal enforcement action search ↗
Industrial and commercial NPDES permits in Maryland
Most NPDES permits are not held by municipal plants. EPA’s permit database lists 665 individual permits in force for industrial and commercial facilities in Maryland (manufacturers, food processors, mines, power plants, landfills), 39 of them major dischargers, plus 1,753 facilities covered by a general permit, mostly for stormwater. 101 of the individual permits recorded at least one effluent violation in the last three years.
| Facility | Permit | Status | Expires | Effluent violations |
|---|
Unlock 665 industrial permits in Maryland
Search every industrial and commercial discharger in Maryland by name or permit number, with permit status, expiry and violation history. Free with a Klarifi account.
Industrial and commercial NPDES permits in Maryland: permits in force (effective or administratively continued) held by facilities EPA does not class as publicly owned treatment works or federal facilities. Source: EPA ICIS-NPDES via Klarifi, October 2026.
Violations at Maryland wastewater plants
78 of the 118 municipal plants on this page recorded at least one effluent violation, a monitored value above a permit limit, in the last three years, and 93 had a violation of any kind, including late or missing monitoring reports. Each plant’s page shows its own count. EPA’s enforcement records list 14 formal cases naming Maryland wastewater plants, 2 of them since fiscal year 2020, with $1.1 million in penalties assessed. Enforcement cases in Maryland →
Permit renewals by year
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.
2029: 10 permits
2030: 38 permits
2031: 24 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 | 107.68 | — | MDL021555 | Effective | Dec 2030 | 32 |
| Patapsco Wastewater Treatment Plant | Baltimore | 51.59 | — | MDL021601 | Effective | Dec 2030 | 22 |
| Little Patuxent Water Reclamation Plant | Savage | 16.76 | 25 | MD0055174 | Effective | May 2031 | 8 |
| Piscataway Swge Plnt | Accokeek | 19.8 | — | MDL021539 | Effective | Dec 2030 | 25 |
| Annapolis WRF | Annapolis | 7.94 | 13 | MD0021814 | Effective | Jan 2030 | 6 |
| Sod Run Wastewater Treatment Plant | Perryman | 9.48 | — | MDL056545 | Effective | Dec 2030 | 0 |
| City Of Frederick Wastewater Treatment Plant-2012 | Frederick | 5.68 | 8 | MD0021610 | Effective | May 2031 | 23 |
| Ballenger-Mckinney WWTP | Frederick | 7.11 | 7 | MD0021822 | Effective | Dec 2030 | 1 |
| Parkway Wastewater Treatment Plant | Laurel | 6.09 | — | MDL021725 | Effective | Dec 2030 | 2 |
| The City Of Bowie (ssos) | Bowie | 5.09 | — | MDL021628 | Effective | Dec 2030 | 7 |
Maryland NPDES permits: questions
NPDES permit search in other states
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 October 12, 2026.
Wastewater terms: NPDES permit · POTW · Significant industrial user · MGD · Filter press · FOG · all terms