(Bloomberg) -- The US Supreme Court let Equitrans Midstream Corp. resume construction on its controversial Mountain Valley Pipeline, granting a company request and lifting lower-court orders that had blocked work on the $6.6 billion project.

In a three-sentence order Thursday, the high court stopped short of tossing out lawsuits by environmental groups, something the pipeline had suggested as an alternative. But the justices left open the possibility they might do so at a later stage, saying, “that determination is without prejudice to further consideration in light of subsequent developments.”

The Supreme Court gave no explanation and no justice publicly dissented.

The high court issued the order even as the 4th US Circuit Court of Appeals heard arguments in Richmond, Virginia, about next steps in the case. The pipeline and the Biden administration are asking the 4th Circuit to dismiss the suits. The three-judge panel concluded the argument without indicating how quickly it will rule.

Shares of Equitrans jumped 9.3% as of 1:09 p.m. in New York trading.

The roughly 300-mile (483-kilometer) pipeline, backed by Democratic Senator Joe Manchin, cuts through the Appalachian Mountains, a national forest and hundreds of stream crossings as it carries natural gas from his home state of West Virginia to southern Virginia, and has drawn fierce opposition from environmental activists.

“The Supreme Court has spoken and this decision to let construction of the Mountain Valley Pipeline move forward again is the correct one,” Manchin said in tweet after the decision. “I am relieved that the highest court in the land has upheld the law Congress passed and the President signed.”

Equitrans has said it has three months of work remaining to complete the project and needed to resume construction by Wednesday in order to put the pipeline into service before year-end.

The high court’s move “adequately preserves the possibility that the pipeline can be placed in service this year, should weather and any other unforeseen circumstances permit,” Height Securities LLC said in a research note.

The 4th Circuit temporarily blocked construction earlier this month despite language in recently enacted debt-ceiling legislation that was intended to prevent the pipeline from being stalled by the lower court, which has repeatedly ruled against the project.

Read More: Court Stalls Pipeline That Joe Manchin Thought It Couldn’t Touch

Environmental opponents of the project vowed to keep fighting. 

“The Mountain Valley Pipeline is a threat to our water, our air and our climate,” said Jamie Williams, president of the Wilderness Society. “We will continue to argue that Congress’ greenlight of this dangerous pipeline was unconstitutional and will exhaust every effort to stop it.”

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