The U.S. Supreme Court on Monday denied a petition filed by Constitution Pipeline Co. LLC to challenge New York’s regulatory authority and let stand an appeals court ruling that upheld the state’s decision to deny the project a water quality certificate (WQC).

It was yet another setback for the 124-mile natural gas pipeline project that has bounced through the legal and regulatory process for years now. The Supreme Court was asked to review a ruling by the U.S. Court of Appeals for the Second Circuit. The petition was distributed for conference, or discussion, on Friday, but the justices simply denied it.

Constitution received a FERC certificate authorizing the project in 2014. The project’s sponsors have battled the New York State Department of Environmental Conservation (DEC) since 2016, when after nearly three years of regulatory review the agency denied the pipeline’s application for a section 401 WQC required under the Clean Water Act (CWA).

The project’s sponsors vowed on Monday to keep fighting, saying they “continue to believe that this FERC-approved project should be allowed to proceed with construction,” and adding that they are still committed to the pipeline and the remaining regulatory and legal options available.

After the DEC denial, which was mainly related to a disagreement over trenchless crossings and the agency’s contention that it didn’t have enough information to determine the project’s environmental impact, the company petitioned the Second Circuit to review the decision.

The appeals court denied the challenge, with a three-judge panel ruling that the DEC is entitled to its regulatory review under relevant federal laws. Constitution later petitioned the court for a rehearing of the case en banc, which was also denied.

Constitution had argued that without a ruling from the Supreme Court, states could use their authority under the CWA to undermine interstate natural gas pipeline development. Monday’s denial, however, is not the last gasp for the project.

Earlier this year, The Federal Energy Regulatory Commission denied Constitution’s petition for a declaratory order that the DEC waived its authority when it failed to issue a WQC within a reasonable period of time. Constitution has since filed a request for rehearing at FERC, asking the Commissioners to reconsider their decision upholding New York’s authority.

“While we are disappointed in the Supreme Court’s decision not to hear our case, we are still fully committed to pursuing our primary avenue of relief, which is the pending rehearing request with the Federal Energy Regulatory Commission,” said project spokesman Christopher Stockton, adding that the sponsors would, if necessary, also pursue an appeal of FERC’s decision to the U.S. Court of Appeals for the District of Columbia Circuit.

Constitution would provide 650 MMcf/d of takeaway capacity from Susquehanna County in northeast Pennsylvania. About 100 miles of the pipeline would cross New York, connecting with Tennessee Gas Pipeline and Iroquois Gas Transmission near Albany. Constitution is backed by Williams, Cabot Oil & Gas Corp., Piedmont Natural Gas and WGL Holdings Inc. with the aim of delivering Marcellus gas to the underserved Northeast.

The project is not the only one to have met resistance in New York. The state has also denied certificates for National Fuel Gas Co.’s Northern Access expansion project and Millennium Pipeline Co. LLC’s Valley Lateral project.

While Valley Lateral is advancing after the company successfully challenged New York before FERC, the Northern Access project remains bogged down in court. About a week ago, the DEC also denied a WQC for the Northeast Supply Enhancement Project.