Hill Heat

Subcommittee hearing entitled “Corrosion, Collapse, and Clean-Up: Examining the Potomac Interceptor Collapse.”

Hearing memo

Witnesses:

Panel I

• Jessica Kramer, Assistant Administrator, Office of Water, U.S. Environmental Protection Agency;
• Col. Francis B. Pera, Commander, U.S. Army Corps of Engineers, Baltimore District
• Edward Wenschhof, Acting Superintendent, Chesapeake & Ohio Canal National Historical Park, National Park Service, U.S. Department of the Interior.

Panel II

• David Gadis, Chief Executive Officer and General Manager, DC Water
• Tom Neltner, National Director, Unleaded Kids.

The Potomac Interceptor (PI) is a 54-mile sanitary sewer system. The pipe was built between 1961 and 1963 after legislation enacted on June 12, 1960, “authorized the District of Columbia [(DC)] to plan, construct, operate, and maintain a sanitary sewer to connect Dulles to the Washington, DC sewer system.” Today, the PI runs through parts of Virginia, Maryland, and DC, and serves Fairfax County, Loudoun County, the Town of Vienna, Herndon, Dulles Airport, and Montgomery County, Maryland. The PI is located on different land jurisdictions and at various points is located on National Park Service (NPS) property.

The PI is constructed mostly of reinforced concrete pipe (RCP) ranging from “30-inch to 96-inch diameter round, reinforced concrete pipe in the main trunk to 13-foot by 7.75-foot rectangular, reinforced concrete pipe in the lower reaches of the sewer system.” It has eleven tunnel sections and two river tunnel crossings underneath the Potomac River. The PI carries flows of up to 60 million gallons of wastewater daily from Loudoun and Fairfax Counties in Virginia and Montgomery County in Maryland to the Potomac Pumping Station in Washington, DC. Wastewater from the pump station is “sent to the Blue Plains Advanced Wastewater Treatment Plant [in Southwest, DC] for treatment before discharge into the Potomac River.”

Before 1996, the District’s water and sewer functions were housed inside DC government. From 1985 to 1996, what is now known as DC Water operated as the Water and Sewer Utility Administration within the Department of Public Works. In 1996, DC and Congress changed that structure by creating the District of Columbia Water and Sewer Authority, now known as DC Water, as an independent authority of the DC government. This change made DC Water a public utility authority with corporate powers and an operating structure that is separate from the DC government. It is neither a private entity nor a standard DC agency. Rather, it is a public utility authority with its own board, staff, property, contracts, revenues, and debt authority. As such, DC Water has authority to operate and fund infrastructure, not just administer policy. DC Water’s statutory mandate is to plan, build, operate, maintain, finance, repair, modernize, and improve water distribution and sewage collection, treatment, and disposal systems. DC Water can sue and be sued, hire employees, own property, accept grants and loans, contract with DC, the federal government, Maryland, Virginia, and local governments, borrow money, issue revenue bonds, and set service charges. DC law also gives DC Water dedicated revenues from water and sewer rates, fees, and charges imposed by the Authority. It must set rates, fees, levies, and other charges high enough to cover its costs and bond obligations.

DC Water exists pursuant to DC law, but the sewer system it runs is regional. The DC Code lists Blue Plains and the PI Sewer as joint-use sewerage facilities. The same law identifies Montgomery County, Prince George’s County, and Fairfax County as participating jurisdictions. As a result, DC Water’s board has 11 members: six from the District and five from those participating jurisdictions. The outside members participate only in decisions directly affecting joint-use sewerage facilities. Their seats on the board do not make DC Water a Maryland or Virginia agency. The pipe may run through Maryland, the land may be federal park land, and the wastewater may come from several jurisdictions, but DC Water remains the operating authority responsible for the PI.

At the federal level, the U.S. Environmental Protection Agency (EPA) exercises regulatory oversight under the Clean Water Act (CWA). The CWA “establishes the basic structure for regulating discharges of pollutants into the waters of the United States and regulating quality standards for surface waters” and allows EPA to develop pollution control programs. EPA’s jurisdiction includes enforcement of discharge permits under the National Pollutant Discharge Elimination System (NPDES), water quality standards, and oversight of consent decrees or administrative orders that may govern DC Water’s infrastructure investments and compliance obligations. If a collapse of the PI results in unauthorized discharges into the Potomac River or surrounding waters, EPA may initiate enforcement or require corrective actions under Sections 301 and 309 of the CWA.

The U.S. Army Corps of Engineers (USACE) holds jurisdiction over certain aspects of navigable waters and related infrastructure under multiple legal authorities, such as Section 10 of the Rivers and Harbors Act of 1899 and Section 404 of the CWA. If a collapse of the PI or subsequent repair activities affect navigable waters or riverbanks, or require dredging, filling, or construction within federal waters, USACE permits and coordination will be required. USACE may also provide technical assistance or emergency engineering support under the Stafford Act and its own emergency authorities. Additionally, USACE designed, built, and operates the Washington Aqueduct, which produces drinking water for approximately one million people in DC and parts of Virginia, including Arlington County and portions of Fairfax County. On average the Washington Aqueduct produces 135 million gallons of water per day at two treatment locations in DC.

The National Park Service (NPS) owns the land on which a significant portion of the PI runs, and where the PI collapse occurred. If infrastructure is located within or impacts NPS property, NPS approval in the form of permits is required for access, construction activities, and environmental compliance. Special Use Permits for Construction are issued for “any construction-related activity on Park land where the construction-related activity is not the direct result of an official construction contract with the National Park Service” including the “[i]nstallation and/or upgrade of utilities including water, sewer, electric, and/or communications.” Alternatively, Right-of-Way Permits “are appropriate to authorize utility uses such as power lines, water lines, fiber lines, and cellular communications equipment.” NPS must also adhere to the National Environmental Policy Act (NEPA), “which requires federal agencies to assess the environmental effects of their proposed actions prior to making decisions,” when issuing permits for projects. These permitting processes may be long and burdensome which impacts when, and how fast, any repairs can be completed for the PI.

The Federal Emergency Management Agency (FEMA) also had a role in responding to the PI collapse. On February 18, 2026, DC Mayor Muriel Bower declared a “local public emergency” in response to the wastewater spill and “requested federal support through a Presidential Emergency Disaster Declaration request.” A few days later, President Trump approved a federal emergency declaration for DC, which made federal disaster assistance available to supplement the PI collapse response efforts. In doing so, FEMA was authorized to “coordinate all disaster relief efforts to alleviate the hardship and suffering caused by the emergency on the local population and to provide appropriate assistance to save lives, to protect property, public health and safety and to lessen or avert the threat of a catastrophe.”

At the state level, the Maryland Department of the Environment (MDE) “[r]egulates unauthorized discharges into Maryland waterways and wetlands, monitors shellfish harvesting, and oversees drinking water safety and enforcement.” The Virginia Department of Environmental Quality (DEQ) also “initiated a special water quality monitoring initiative to measure bacteria levels along Virginia’s Potomac River shoreline.” This allows the Virginia DEQ to “supplement the sampling efforts of DC Water, the DC Department of Energy & Environment, the Maryland Department of Environment and others.”

Within DC, the District Department of Energy and Environment also exercises complementary regulatory authority over water quality and environmental protection under D.C. Code § 8–151.01 et seq., including local implementation of federal environmental programs and coordination with EPA.

On January 19, 2026, an underground section of the PI, located by Lock 11 on the Chesapeake & Ohio (C&O) canal, collapsed. The cause of the collapse remains under investigation.46 When the collapse happened, boulders that were sitting over the PI fell into the broken section of the pipe and created a blockage of the pipe. With the boulders blocking the pipe, the wastewater had nowhere to go, which created pressure upstream of the break, and the wastewater started to overflow through manholes located upstream from the collapse location.

As the wastewater flowed out of the collapse location and the manholes, it flowed down an unnamed tributary that runs parallel to the Clara Barton Parkway, under the C&O canal via a culvert, and down to the Potomac River by Swainson Island.

DC Water was alerted to the activity via “security cameras [that] detected unusual activity near one of [the] odor control facilities along the Clara Barton Parkway.” DC Water then activated emergency response protocols, including installing a bypass pumping system, and worked to stabilize the damaged pipe. According to DC Water, “[t]he bypass system began operating early January 24, 2026, when six large pumps were turned on to convey wastewater into a controlled section of the C&O Canal, routing it around the break and back into the sewer system further downstream.” While this bypass allowed wastewater to be diverted around the collapse site and back into the PI, initially there were isolated incidents of wastewater overflows due to various factors, such as increased volumes of wastewater due to melting snow or other issues. For example, in early February there was a significant overflow which was estimated to have released “several hundred thousand gallons of wastewater” due to issues with the pumps. Specifically, “[t]he overflow event occurred when multiple pumps were out of service for required cleaning and maintenance after becoming clogged by non-disposable wipes that were flushed into the system,” which also happened during a period of high flow in the sewer system.

According to DC Water, there has not been any release to the Potomac River since February 8, 2026. In March, however, it was determined through sampling, that contaminated water was leaking out of the culvert that is located under the portion of the C&O Canal that was being used as part of the bypass system to route the wastewater around the PI collapse. It is through this culvert that the unnamed tributary flows downstream until it enters the Potomac River. USACE subsequently installed a sandbag dam and pumping operation to divert the water through the pumps and into the PI.

It is estimated that over 240 million gallons of raw sewage flowed into the Potomac River before the overflow was completely contained. For comparison, the Exxon Valdez oil spill of 1989—which has been regarded as “one of the largest environmental disasters in U.S. history”— resulted in 11 million gallons of oil being released into the environment.

On April 20, 2026, the U.S. Department of Justice, on behalf of the EPA, filed a federal CWA complaint against DC Water for the PI failure. On the same day the State of Maryland brought a parallel action seeking civil penalties, cleanup costs, and natural resource damages. These suits allege that DC Water failed to address known severe corrosion in the pipe for years, contributing to the rupture that released more than 200 million gallons of untreated sewage into the Potomac River.