The leader of the agency responsible for the sinking earlier this year of the Potomac Interceptor defended the maintenance practices of the deteriorating 60-year-old sewage pipeline at a congressional hearing on the causes and consequences of the release of more than 240 million gallons of untreated sewage into the Potomac River.
DC Water CEO and CEO David Gadis told members of the House Oversight and Investigations Commerce and Emergencies Subcommittee that the January 19, 2026 incident was not the result of overlooked infrastructure challenges.
“Rather, it occurred within one of the nation’s oldest and most complex wastewater systems — a system that DC Water has spent decades modernizing, rehabilitating and improving for the benefit of the region and the environment,” Gadis said in prepared testimony.
Gadis was joined by representatives from the U.S. Environmental Protection Agency, the U.S. Army Corps of Engineers and the U.S. National Park Service, who added perspectives on the two-month emergency effort to contain the spill and the resulting environmental damage, including a section of the Chesapeake and Ohio Canal National Historic Park that was used for several weeks as a temporary diversion channel for daily sewage flows from 60 million gallons.
No total cost for the response, remediation and environmental remediation effort has been announced, but reports have said it could be more than $20 million, with the advocacy group Potomac Conservancy estimating it as high as $50 million.
Gadis noted that the location of the collapse within the environmentally sensitive park “significantly increased the complexity of both emergency operations and long-term rehabilitation planning.”
lessons learned
Asked by subcommittee members, he explained that a section of pipe spanning the collapse site had already been identified in 2018 for corrosion and rebar repair, but construction had been hampered by a lengthy National Park Service permit review process that had not yet been completed when the incident occurred.
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Park Service officials said the permit application “had to go through the process,” Gadis said DC Water was repeatedly told. “This is everything we were waiting for,” he added.
“Having long-term easements to access the Potomac Interceptor, standardized permitting timelines, streamlined reviews for similar rehabilitation work, and better field coordination with regulatory authorities can help prevent the failure from happening again,” Gadis said in his testimony. “We take seriously our obligation to learn from this incident and strengthen our systems.”
Citing pending litigation from state and federal lawsuits filed against DC Water earlier this year, C&O Canal Park Acting Superintendent Edward Wenschhof declined to answer key questions about the permitting process or whether the agency believed a pipe break was imminent. The park official said that in most cases, reviews of building permits proposed by utilities could take six months to a year.
“There are others that are identified as high priority,” he added.
In an April Washington Post investigation, a Park Service spokesman insisted the lengthy environmental assessment process resulted from remedial plan changes initiated by DC Water, something Gadis told the subcommittee had only happened twice. In one case, according to the Post’s investigation, DC Water underestimated the number of trees affected by the proposed remediation effort, prompting the Park Service to require an in-depth assessment instead of approving a fast-track permit.
While the specific cause of the collapse has not been determined, Gadis said large rocks and debris suspected to have been used as fill during the pipeline’s original construction may have been a contributing factor.
“Collectively, weighing approximately 18 tons … these materials obstructed flow within the pipeline and likely contributed to significant structural stress on the Interceptor over many decades,” Gadis testified, adding that the resulting blockage significantly complicated emergency response and rehabilitation operations.
“The blocks restricted access to damaged sections of the pipeline, impeded wastewater flow, created dangerous and unstable working conditions for crews, and substantially increased the complexity of excavation and debris removal efforts within a very limited, environmentally sensitive work area. All during historically cold and icy weather,” Gadis noted. As a result, the response proved much more difficult to operate, requiring “specialized equipment, careful staging, ongoing coordination between engineering and environmental teams, and extensive safety precautions to protect workers, nearby infrastructure, and the surrounding river environment.”
Strengthen the evaluation of the system
DC Water reports no more spills since emergency repairs ended in March. Efforts to clean the floor of a section of canal used as an emergency bypass are nearly complete, while permanent repair is progressing on a 2,700-foot section that includes construction of a bypass chamber to divert wastewater around the pipe sections while it is being rehabilitated. Daily water quality testing by DC Water at ten downstream sampling sites continues to show levels of E. coli within normal safe ranges.
Gadis also told the subcommittee that the agency has stepped up condition assessments of the entire 54-mile Potomac Interceptor system, using ground-penetrating radar to augment inspections.
Three areas that need immediate attention for repair are being prioritized, with mobilization planned for this summer, but Gadis did not specify their location or the status of contracted works.
“You have to look at the outside of the pipe and the inside,” he told the subcommittee, adding that if the agency had known about the rocks at the top of the pipe, “we would have dug them out and replaced them with clean fill.”
Asked whether DC Water’s efforts will be enough to prevent a similar major failure of the Potomac Interceptor in the future, Gadis said that while the agency hopes it will, “there are no guarantees” when dealing with aging infrastructure that is more than 60 years old.
“This was a preventable environmental disaster. After four months, we still don’t know what needs to change to prevent it from happening again,” the Conservancy said. “Through transparency and a full accounting, we can correct course with a clear plan to prevent future mistakes, address needed repairs on National Park Service lands, invest in long-overdue water infrastructure, and develop a long-term restoration strategy for the Potomac River.”
