TWW Self-Reported Matter to Regulators; Drinking Water Quality and Service Are Not Affected
TRENTON, N.J. — Trenton Water Works (TWW) has received a Notice of Violation related to a cofferdam associated with the water utility’s raw water intake on the Delaware River, a matter that TWW identified and self-reported to the New Jersey Department of Environmental Protection.
The Notice of Violation addresses regulatory requirements related to the cofferdam and does not indicate a violation of drinking water quality standards. TWW continues to safely withdraw raw water from the Delaware River for treatment at its water filtration plant, and there has been no interruption to water service as a result of the matter.
The current raw water intake, an approximately $9 million infrastructure project completed in 2022, was designed by an engineering firm retained pursuant to public bidding laws to replace a concrete intake structure that had been in service since 1954. The project was intended to improve the reliability and resilience of TWW’s raw-water withdrawal from the Delaware River.
As part of the construction project, a contractor, supervised by the contracted engineering firm, erected a cofferdam as a temporary structure to facilitate construction of the new raw water intake. The cofferdam was supposed to be removed upon completion of the work; however, TWW has determined, following a survey conducted by a water-resource consultant engaged by TWW, that drone footage revealed that the builder did not completely remove the structure as required, leaving portions of it in the Delaware River. The remaining cofferdam material is the subject of the regulatory matter that TWW identified and self-reported.
TWW’s preliminary review of the matter has identified deficiencies in the design and construction of the raw water intake project. The water utility maintains that the condition of the cofferdam resulted from failures associated with that work and will be taking appropriate action, including removal of the cofferdam and possibly pursuing legal action to protect the interests of TWW and its ratepayers.
“The violation requires that the cofferdam be removed, and we will comply,” said Michael Walker, TWW’s Chief of Communications and Public Outreach. “We will add the cost of removing it to the list of claims the water utility will pursue against the responsible parties whose work was incompatible with the project’s specifications and our expectations.”
During the winters of 2025 and 2026, water filtration plant operators have had to bypass the new raw water intake using high-capacity pumps—the plant’s standing and effective backup plan, if needed again—at times because of frazil ice buildup on the intake screens to maintain the flow of raw water into the water filtration plant for treatment. Operators have also had to use the intake’s pressurized-air system more frequently to dislodge accumulated ice from the screens and maintain adequate water flow. It is believed that deficiencies in the design and/or construction of the raw water intake project are the cause of the frazil ice buildup.
Frazil ice and other cold-weather ice formations are recognized operational challenges for surface-water utilities throughout the United States. In January 2026, Pittsburgh Water reported that ice obstructed its Allegheny River raw-water intake, reducing the amount of water available for treatment and requiring crews, a barge, and a tugboat to help break up the obstruction. That same winter, the City of Huron, Ohio, reported that its primary Lake Erie raw-water intake was blocked by ice and deployed large mobile pumps along the shoreline to provide an alternative raw-water supply to its treatment plant. Avon Lake Regional Water in Ohio has experienced frazil ice accumulation at its Lake Erie intake and has subsequently modified its intake grates and installed an air-powered ice-control system. The Town of Williamson, New York, also reported in 2026 that frazil ice accumulated in its raw-water intake, restricting the amount of water it could withdraw and prompting conservation measures and the use of interconnections with neighboring water systems.
“TWW identified and self-reported the cofferdam issue to our regulators, and we are taking the appropriate steps to address it,” Walker said. “The temporary cofferdam should have been completely removed when construction was finished. At the same time, the winter operating challenges we have experienced demonstrate why a raw water intake on a major river must be engineered to perform reliably under severe environmental conditions, including extreme cold and frazil ice. We intend to hold accountable the parties responsible for the design and construction of this approximately $9 million infrastructure investment and protect our ratepayers from bearing the financial consequences of deficient engineering or construction work.”
The raw water intake is a critical component of TWW’s water filtration plant. It allows the water utility to draw untreated water from the Delaware River before it undergoes a comprehensive treatment and disinfection process at the water filtration plant and is delivered to customers throughout TWW’s service area. The intake is equipped with screens designed to prevent organic matter, debris, wildlife, tree limbs, and other materials in the Delaware River from entering the plant as raw water is drawn in for treatment. The current intake was also designed with features intended to provide resilience against ice buildup and to maintain reliable raw water flow during cold-weather conditions.
TWW is reviewing the Notice of Violation and will complete any corrective actions, engineering work, permitting requirements, or other measures required by regulators. The water utility will continue to work cooperatively with the appropriate regulatory agencies while addressing the cofferdam and pursuing its claims concerning the design and construction of the raw water intake project.
The Notice of Violation does not affect the safety of the drinking water being delivered to TWW customers. TWW continues its routine water-quality monitoring and treatment operations in accordance with the federal and state Safe Drinking Water Acts and applicable regulatory requirements. TWW conducts extensive water-quality testing throughout the treatment and distribution processes, including continuous monitoring at the water filtration plant, laboratory analysis, and routine sampling throughout the distribution system. These testing regimes provide TWW and its regulators with data to verify that treated drinking water meets applicable federal and state standards before and during delivery to customers.
Residents with questions may contact TWW Community Relations at (609) 989-3033.
# # #