This map shows the location of the sewage release along with five other sites along the Potomac River where bacteria samples were collected by DC Water. Map Courtesy of DC Water.
On January 19, 2026, the Potomac Interceptor experienced a breach, releasing an estimated 243–300 million gallons of untreated wastewater from a 72-inch DC Water main into the Potomac River. Remediation efforts have been ongoing for the past 25 days. As a precaution, emergency shellfish closures are in effect from Charles County to the Route 301 Bridge, and health advisories remain active in Montgomery, Prince George’s, and Charles counties. All active Maryland drinking water intakes are upstream and unaffected. The bypass system is operational, helping to manage the overflow, though some secondary discharges may still occur due to pump clogs and snowmelt.
This event is classified as a sanitary sewer overflow (SSO), which happens when untreated wastewater is released from a sewer system due to infrastructure failure, blockages, or pump malfunctions.
Key Agencies
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District of Columbia Water and Sewer Authority (DC Water): Pipe owner/operator; responsible for bypass, repairs, cleanup, and public signage. Gives operational updates to state and federal partners
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United States Environmental Protection Agency (EPA): Primary regulator and lead federal enforcement and compliance authority; enforces federal Clean Water Act regulations and oversees DC Water/Blue Plains consent decree.
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Maryland Department of the Environment (MDE): Regulates unauthorized discharges into Maryland waterways and wetlands, monitors shellfish harvesting, and oversees drinking water safety and enforcement.
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Maryland Department of Health: Coordinates with local health departments on water contact advisories.
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Virginia DEQ & VDH: Monitors downstream water quality and public health.
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DC Department of Energy and Environment:
Supports water, quality, monitoring, and issuing public health advisories for District residents.
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Supporting Entities: National Park Service and the Interstate Commission on the Potomac River Basin coordinate monitoring, modeling, and river management, as well as oversee some permitting.
Environmental Impacts
Category |
Status |
Details |
Drinking Water |
SAFE |
Intakes are located upstream of the spill. |
Shellfish |
ONE AREA CLOSED |
Precautionary closure from
Charles County to Nice Bridge. No active leases and no closures further downstream. |
Recreation |
AVOID |
Health advisories active in
three counties (Montgomery, Prince George’s, Charles). |
Containment |
SUBSTANTIALLY COMPLETE |
Bypass installed; most flow is diverted but occasional disruption. Last overflow incident occurred February 9. |
Maryland Department of the Environment (MDE) Response Actions
Coordination, Directions and Inspections
The response efforts include daily coordination, with consistent site visits. The primary goal of these visits is to oversee containment activities and assess the extent of the environmental damage caused by the incident.
Shellfish Protections
To safeguard public health and ensure consumer safety, a precautionary harvesting closure has been issued, encompassing the area from Charles County up to the Route 301 Bridge. As part of this measure, water samples are being collected and sent for analysis.
Ongoing Monitoring
A coordinated monitoring plan has been implemented to track the situation at the spill site and other locations in Maryland and Washington, D.C. As ice continues to clear, efforts will focus on collecting additional samples from open water areas.
Health Coordination
State and local health departments are receiving support to disseminate essential public safety advisories in the three counties impacted by the incident, ensuring residents are informed and protected.
Long-Term Recovery
Restoration plans for the affected areas will be reviewed and approved in close coordination with key partners, including the U.S. EPA and the National Park Service.
Sampling Results From DC Water
Note: MPN = Most probable number
* Consistent with public health and U.S. Environmental Protection Agency standards, swimming is not recommended when E. coli levels exceed 410 MPN/100mL
Historical data indicate typical E. coli levels in the Potomac River can range from 10 to 5,000 MPN/100mL. Variability in E. coli results are common and are influenced by multiple factors, such as weather (rainfall/snow melt and associated runoff) and subwatershed activities and conditions, including aging sewer infrastructure and illicit discharges.
Timeline
January 2026 |
Agency |
Action / Response |
Jan 19 |
DC Water |
The 72-inch Potomac Interceptor sewer line collapsed. DC Water began emergency response, investigating the collapse and reporting the ongoing overflow. |
Jan 20 |
MDE |
Conducted first site inspection, alongside EPA (lead response agency) and DC Water |
Jan 21–23 |
DC Water |
Crews worked to install bypass pumps to reroute wastewater around the damaged section. |
Jan 24 |
DC Water |
The bypass system was completed and activated, diverting most wastewater back into the system and containing some overflow. |
Jan 24 |
MDH, PG County Health Dep, Charles County Health Dep |
Non-contact health advisories issued advising citizens to avoid direct contact with the river |
Jan 25 |
MDE |
Issued a precautionary shellfish harvesting closure north of the Route 301 Bridge, before impacts were confirmed, to protect public health and market confidence. (The closure is a standard 21-day post-overflow timeframe once the discharge is fully stopped.) |
Jan 25–30 |
DC Water |
Excavation began to access the damaged pipe; trench shields and soil stabilization were installed. Testing for E. coli and bacterial contamination began at multiple sites. |
Jan 29 |
MDH, Montgomery County Health Dep |
Non-contact health advisories issued advising citizens to avoid direct contact with the river |
Jan 29 |
MDE |
Conducted site inspection with EPA, DC Water |
February 2026 |
Agency |
Action / Response |
Early Feb |
DC Water |
Released key findings estimating ~243 million gallons had spilled before containment. |
Feb 5–6 |
DC Water |
Inspection revealed a significant rock blockage inside the collapsed pipe, complicating repairs. DC Water warned repairs could take 4–6 additional weeks and mobilized larger equipment. |
Feb 5 |
MDE |
Conducted site inspection with EPA, DC Water |
Feb 8–10 |
DC Water |
Acknowledged a sampling error and significantly corrected reported E. coli levels upward. |
Feb 11–12 |
DC Water |
The CEO issued an open letter outlining ongoing work and emphasizing transparency. |
Feb 11 |
MDE |
Conducted a site inspection with EPA and DC Water |
Feb 12 |
MDE |
Collected samples at routine shellfish sampling stations for analysis. |
Feb 13 |
MDE |
Conducted site inspection |
ASAP (Anticipated) |
MDE |
Anticipated results of the Feb 12 samples to be published. |
Additional information
Frequently Asked Questions
MDE presentation - Maryland General Assembly hearing (Feb. 13, 2026)
MDE inspection reports (enter site number 72092)
MDE shellfish emergency closure
EPA information letter to DC Water
DC Department of Energy & Environment
DC Water
Montgomery County health advisory
Prince George’s County health advisory
Charles County health advisory
Interstate Commission on the Potomac River Basin
Potomac River Fisheries Commission
Potomac Riverkeeper Network
