A federal appeals court has overturned New Jersey’s water quality certification for Williams Cos. The more than $1 billion Northeast Supply Improvement Natural Gas Pipeline found that state regulators left critical monitoring requirements unresolved and inadequately explained how dredging Raritan Bay would meet state standards.
The United States Court of Appeals in Philadelphia on September 8 sent the Clean Water Act Section 401 certification to the New Jersey Department of Environmental Protection for further proceedings.
The decision comes less than three weeks after an independent federal appeals court upheld New York’s water quality certification for the same project. ENR reported Aug. 24 that state approval requires review of compliance plans before applicable construction begins, as well as an independent third-party monitor with stop-work authority and specified pollutant limits. The court cited these guarantees to distinguish New York’s approval from New Jersey’s.
The Williams Northeast Supply Improvement Project would add 400,000 decatherms per day of pipeline capacity to a Northeast gas market supplied by several regions, storage, local production and LNG.
Chart courtesy AOGR
The pipeline would add approximately 37 miles of line capacity and related facilities to Williams subsidiary Transcontinental Gas Pipe Line Co.’s system, increasing it by 400,000 dcmd to serve National Grid customers in New York City and Long Island. Williams continues to target Q4 2027 service.
Williams spokeswoman Cherice Corley told Reuters by email that the company is working with state regulators to address the court’s findings and remains committed to moving forward with the project.
“At this time, we do not expect the decision to adversely affect the project’s construction or anticipated operating schedule,” he said.
Ben Dziobek, executive director of Climate Revolution Action Network, called the decision a victory for Raritan Bay communities. “No fossil fuel company, no matter how much political support it has in Washington, is successful in reducing the protections our communities are entitled to,” he said.
In New Jersey, work includes a new compressor station in Somerset County, the 3.4-mile Madison Loop in Middlesex County and about six miles of offshore pipeline in Raritan Bay. Installation of the subsea segment requires dredging a trench, laying the pipe, and filling it.
The court said the sediment along the route contains pollutants such as arsenic, manganese, mercury, polychlorinated biphenyls and 4,4′-DDE, a breakdown product of DDT.
Unresolved follow-up requirements
The New Jersey Department of Environmental Protection and New York regulators issued their Section 401 certifications on November 7, 2025.
New Jersey’s certification required Transco to submit water quality monitoring and adaptive management plans, but did not make approval of those plans a prerequisite for dredging. Material issues remain unresolved, the court said, including thresholds that would trigger mitigation measures, how quickly exceedances must be reported and whether dredging would stop if remedial measures failed.
The Raritan Bay Loop of the NESE project crosses the waters of New Jersey and New York, where planned undersea pipeline construction requires dredging and filling along the route. Click to enlarge.
Map courtesy of Williams Cos.
“There is no prescribed NJDEP approval between the unfinished plans and the dredging,” the court said.
Transco’s modeling predicted concentrations of 4,4′-DDE at two sampling sites within 500 feet of the dredge that exceeded the New Jersey human health criterion. At one site, the modeled concentration was more than 13 times the criterion. The final certification reduced the allowable dredging rate and required work during low tide in that area, but the court said DDE concentrations were not recalculated under those operating conditions.
The New Jersey Department of Environmental Protection also required monitoring of turbidity, but not of the toxic pollutants themselves. The court said the agency had failed to explain why monitoring water cloudiness would ensure compliance with standards governing DDE, PCBs, mercury and other pollutants.
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The judges also found that the department credited state marine experts with a prediction that the affected clam populations would recover within one to three years when the prediction actually came from Transco.
The court found that the unresolved compliance measures and inadequately explained technical findings made the certification arbitrary and capricious. Because those flaws required a vacatur, the justices did not rule on the environmental groups’ separate claims about the public comment process.
The New Jersey Department of Environmental Protection is not required to reject the project on pretrial detention. The court said the agency can supplement its explanation, require additional submissions or analysis, issue a new or revised certification or reach a different result.
