Sewer overflows in Maryland
Sewer overflow record — reported spills, the worst utilities, and how often overflows reached waterways in Maryland.
Reported events
30,714
Total volume
2.7B gal
Reached waterways
0(0%)
Latest event
Jun 28, 2026
Worst utilities in Maryland
Ranked by number of reported overflow events.
Biggest spills in Maryland
The largest single reported overflow events.
- 772.2M galMay 13, 2025Reached Will's Creek & Potomac River
- 280.0M galJan 19, 2026Reached Roadside ditches, C&O Canal, Potomac River
- 257.5M galMar 2, 2024Reached Patapsco River
- 76.2M galMar 23, 2024Reached Patapsco River
- 52.2M galApr 2, 2024Reached Wills Creek & Potomac River
- 51.6M galDec 11, 2023Reached Potomac River
- 42.0M galMay 30, 2025Reached N/A
- 40.7M galMay 27, 2025Reached Wills Creek & Potomac River
- 40.7M galMay 27, 2025Reached Potomac River and Wills Creek
- 40.0M galMay 24, 2025Reached None.