Maryland is suing DC Water, the utility company behind the sewage line that spilled an estimated 243 million gallons of raw sewage into the Potomac River in January.

Through the lawsuit, filed Monday, the state’s Office of the Attorney General and the Maryland Department of the Environment are seeking civil penalties against DC Water, as well as repayment for the costs of cleaning up the river.

“Millions of gallons of raw sewage in the Potomac River does not just disappear, it damages ecosystems and harms communities, and it demands accountability,” Attorney General Anthony Brown said in a Monday news release. “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. We are going to court to make sure they make it right for Marylanders.”

On Jan. 19, a section of the Potomac Interceptor sewage line in Montgomery County ruptured, spilling raw sewage into the Potomac River for eight days. The Potomac Interceptor system, built in the 1960s, carries over 60 million gallons of sewage daily from the Virginia and Maryland suburbs to a wastewater treatment facility in Washington, D.C. The concrete pipeline runs along the Potomac for much of its 54-mile route.

In the Monday lawsuit, Maryland officials argue that DC Water was aware for over a decade before the January rupture that the Potomac Interceptor line was corroding and in need of replacement.

“DC Water has acknowledged that inspections between 2011 and 2015 of individual segments of the Potomac Interceptor indicated that the majority of the pipe showed signs of corrosion,” the lawsuit reads. “Furthermore, DC Water has acknowledged that such inspections did not use methods for assessing the pipe’s conditions according to the industry-wide standard.”

Under state law, DC Water is liable for up to $10,000 in civil penalties for each day that it violated state water pollution control laws. The lawsuit asks the court to force DC Water to pay for all the past and future costs of water testing, cleanup and monitoring, as well as damages for the “lost use and value of [Maryland’s] natural resources.”

The state also asked for an injunction requiring DC Water to stop all discharges into the Potomac and to “restore the state’s natural resources to their original condition prior to the contamination.”

Officials from the Attorney General’s Office were not immediately available to answer questions about exactly how much Maryland has already spent on cleanup related to this rupture.

The company began a long-term repair project to address corrosion in the Potomac Interceptor system during fiscal year 2025, over a decade after it discovered corrosion in the system.

State authorities began river cleanup efforts immediately, but these efforts are far from complete, the lawsuit says. Testing in the area detected levels of E. coli in the river above the U.S. Environmental Protection Agency’s limit, prompting public health advisories in Montgomery, Charles and Prince George’s counties that remained in place well into March.

DC Water also built a bypass for sewage to avoid the location of the spill, which it completed eight days after the initial spill. According to the lawsuit, this bypass also ruptured at least four times in February. Officials from DC Water announced last month that repairs to the Potomac Interceptor system could take up to nine months.

DC Water could not immediately be reached for comment.

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