The segment where the rupture occurred had been targeted for repair under DC Water’s $625-million, 10-year rehabilitation program for the 60-year-old pipeline, but other areas along the 54-mile route were addressed first, including a nearby section where work began last year.

DC Water has yet to pinpoint the exact cause of the incident, which occurred on a section of pipeline in Maryland within the C&O Canal National Historical Park. A Washington Post investigation published in early April found that DC Water had proposed a repair plan for the section as recently as 2018. 

But lengthy federal environmental reviews by the National Park Service, as well as multiple DC Water-initiated repair revisions, stymied the effort. DC Water has also stated that recent inspections have found continued corrosion in the section, but no indication of imminent failure.

Despite a marathon emergency repair effort that restored the Potomac Interceptor’s integrity in mid-March, pending permanent repairs, Maryland’s lawsuit alleges the initial major spill and several smaller subsequent overflows caused extensive damage to the river and adjacent shoreline in violation of multiple state environmental laws. 

Recent inspections by the state Dept. of the Environment found spill-contaminated soil in the vicinity of the Potomac River, the complaint also asserts.

“Millions of gallons of raw sewage in the Potomac River does not just disappear, it damages ecosystems and harms communities, and it demands accountability,” said Maryland Attorney General Anthony G. Brown in a statement announcing the lawsuit. 

“DC Water knew this aging infrastructure was corroding, yet it delayed repairs and failed in its duty to protect this treasured waterway, failures that we allege constitute gross negligence,” he added.

Maryland’s lawsuit seeks civil penalties of up to $10,000 per day for each violation, as well as reimbursement for environmental testing and cleanup costs, and damages for the “lost value of the state’s natural resources.”

Similar allegations of improper maintenance are included in the federal civil complaint, filed by the U.S. Department of Justice on behalf of the Environmental Protection Agency, which led the emergency response and cleanup effort in coordination with the U.S. Army Corps of Engineers and other agencies. 

The lawsuit seeks financial penalties from DC Water and the District of Columbia for violations of the federal Clean Water Act, as well as the costs of mitigating the resulting damage.

“This judicial action serves as the necessary next step in the federal response to the collapse of the Potomac Interceptor and will help prevent future collapses,” said EPA Assistant Administrator for Enforcement and Compliance Assurance Jeffrey Hall in a statement. 

In its response to the lawsuits, DC Water says the legal actions underscore the agency’s commitment to repairing the entire Potomac Interceptor, including accelerating the full rehabilitation of the failed section and rehabilitation of affected areas.

“Initial environmental remediation efforts are also nearly complete, with ongoing water quality testing showing that downstream conditions have returned to normal and have remained stable for several months,” the agency said in a statement. “In addition, recent testing results continue to indicate low bacteria levels near the site of the break.”