The precedential ruling found that NJDEP left dredging controls unresolved and failed to explain how its monitoring plan would protect Raritan Bay from toxic sediment.
TRENTON, NJ – A federal appeals court has vacated a required New Jersey water-quality certification for the more than $1 billion Northeast Supply Enhancement pipeline, finding that state regulators failed to adequately explain how dredging contaminated sediment in Raritan Bay would comply with New Jersey’s standards.
The precedential decision, issued Tuesday, Sept. 8, sends the application back to the New Jersey Department of Environmental Protection. The project remains alive: NJDEP may request more analysis, provide a fuller explanation, issue a new or revised certification or reach a different decision.
The court did not find that the pipeline can never satisfy New Jersey law. It found that the certification NJDEP issued on Nov. 7, 2025, did not contain the reasoning and enforceable controls needed to support the agency’s conclusion.
Judge Jane Richards Roth wrote the unanimous opinion for a three-judge panel of the 3rd U.S. Circuit Court of Appeals. Judges Cheryl Ann Krause and Arianna J. Freeman joined the decision.
A required state approval
The Northeast Supply Enhancement project, known as NESE, would expand the existing Transco interstate gas system operated by Transcontinental Gas Pipe Line Co., a subsidiary of Williams Companies.
The Federal Energy Regulatory Commission has authority over interstate natural-gas facilities. The Clean Water Act separately requires a state to certify that construction-related discharges in its waters “will comply” with federal and state water-quality requirements.
Vacating New Jersey’s certification removes one of the approvals Transco needs for construction in state waters. The ruling does not invalidate the project’s other permits or directly decide what work may continue outside New Jersey.
According to Williams’ project description, construction in New Jersey would include a 3.4-mile, 26-inch pipeline loop in Old Bridge and Sayreville, a new compressor station in Franklin Township, Somerset County, and 6.2 miles of new pipeline associated with the Raritan Bay crossing, including six miles beneath New Jersey waters.
The expansion would add about 400,000 dekatherms of daily transportation capacity, roughly 400 million cubic feet of natural gas per day, between Pennsylvania and New York. Williams says that amount is equivalent to the daily energy needs of approximately 2.3 million homes.
Controls remained unfinished
NJDEP’s certification imposed several restrictions intended to limit sediment movement. Transco would have to use closed clamshell dredging buckets, reduce the dredging rate in the area with the highest predicted contaminant concentrations and work during periods of slack tide.
The court found that other parts of the compliance system remained unresolved.
NJDEP required Transco to submit a final water-quality monitoring plan within 60 days, but the certification called only for agency review. It did not require NJDEP to approve the plan before dredging began.
A separate adaptive-management plan was supposed to identify construction changes that could be used if turbidity increased. The certification set no submission deadline, required no NJDEP approval before dredging and said “some or all” of the measures could be employed.
Eight days before issuing the certification, NJDEP was still asking Transco what turbidity level would trigger corrective action, how quickly exceedances would be reported and whether dredging would stop if corrective measures failed.
The court found that those were material compliance terms rather than minor details.
New York’s certification for its portion of the same project, which the 2nd U.S. Circuit Court of Appeals upheld in August, contained different controls. According to the Third Circuit, New York required agency approval of most compliance plans before construction, established an independent monitor with stop-work authority and placed toxicity limits for roughly a dozen pollutants directly in the certification.
The contaminant analysis
NJDEP had previously identified Raritan Bay sediment samples exceeding screening benchmarks for arsenic, manganese, mercury, polychlorinated biphenyls and 4,4’-DDE, a breakdown product of the pesticide DDT.
Transco modeled contaminant concentrations 500 feet from dredging. NJDEP and Transco told the court that the boundary was not a formal regulatory mixing zone, and the judges agreed that the certification did not formally create one.
NJDEP still had to explain why measurements at 500 feet demonstrated compliance in waters closer to the dredging, the court found.
New Jersey’s human-health criterion for 4,4’-DDE is 0.00022 micrograms per liter. At two sampling locations, Transco’s model predicted peak concentrations of 0.001 and 0.003 micrograms per liter at the 500-foot boundary under one proposed dredging rate. The higher result was more than 13 times the numerical criterion.
The court did not decide that those predictions establish a violation. NJDEP could have explained why the human-health criterion did not apply, required modeling under the final dredging conditions or identified a state-law basis for permitting a temporary exceedance. Its certification did none of those things, the judges found.
Monitoring cloudiness instead of contaminants
The certification required Transco to monitor turbidity, or water cloudiness caused by suspended particles. It did not require direct monitoring for DDE, PCBs, mercury or the other contaminants identified in the sediment.
The court agreed that New Jersey regulations give NJDEP discretion to select the appropriate monitoring method. The agency was not required to test directly for every contaminant.
NJDEP did have to explain why turbidity could be used to determine compliance with separate standards for toxic chemicals. That connection did not appear in the certification or its supporting documents.
“Technical expertise does not relieve an agency of its obligation to articulate the basis for its decision,” Roth wrote.
Shellfish findings did not match the state memo
The affected portions of Raritan Bay are designated for uses that include shellfish harvesting, recreation and protection of the existing ecosystem.
NJDEP said the state Marine Resources Administration determined that sedimentation would remain within surf-clam tolerances and that the habitat would return to its prior condition within one to three years.
The court found that the marine agency’s memorandum did not make those findings. The document quoted Transco’s prediction of a one-to-three-year recovery period without adopting it.
The marine agency instead found that construction would directly and indirectly affect productive surf-clam beds and could cause mortality and physiological stress. Its statement that some effects would be temporary concerned hard clams, a different species.
The court found that NJDEP attributed Transco’s conclusion to its own marine experts, leaving another gap between the evidence and the certification.
What the court rejected
The environmental groups also argued that NJDEP had arbitrarily reversed its 2019 denial of the project.
The judges rejected that claim. NJDEP’s 2019 decision found that Transco had not supplied enough modeling and monitoring information to demonstrate compliance. Transco later submitted a contaminant report and a draft monitoring plan, making the 2025 record materially different, the court found.
NJDEP denied another application in 2020 after New York rejected the corresponding portion of the project, leaving the pipeline without a functional endpoint. New Jersey did not reach the newer water-quality materials on their merits that year.
The court also declined to decide whether NJDEP denied the public an adequate opportunity to comment on revised stormwater materials and the unfinished monitoring plans. A new certification process would give the agency an opportunity to address those concerns, the opinion said.
Reliability, cost and environmental risk
Williams says the pipeline would improve reliability and affordability in New York City and reduce the use of fuel oil delivered by truck. Environmental organizations that brought the cases dispute the project’s need and say dredging would threaten wetlands, water quality and marine habitat.
Those competing energy-policy claims were outside the court’s decision.
Williams held a groundbreaking ceremony in Brooklyn in April 2026 and had planned to place the expansion in service during the fourth quarter of 2027. Company spokeswoman Cherice Corley told Courthouse News Service that Williams is reviewing the ruling.
“The Northeast Supply Enhancement project remains critical to strengthening energy reliability and meeting the region’s growing energy demand,” Corley said.
The Third Circuit’s ruling requires NJDEP to reconsider the certification and state the evidence supporting any new decision. The opinion sets no deadline for that review.