Signs mark the route of the Atlantic Coast Pipeline in Deerfield, Va. (Steve Helber/AP)

A federal appeals court has nullified a key permit for Dominion Energy’s Atlantic Coast Pipeline, finding that restrictions against harming wildlife are inadequate and halting some work on the controversial 600-mile natural gas project.

Three judges of the U.S. Court of Appeals for the 4th Circuit said in a ruling issued late Tuesday that the U.S. Fish and Wildlife Service had failed to set clear limits for impact on threatened or endangered species.

The judges said that “the limits set by the agency are so indeterminate that they undermine . . . the enforcement and monitoring function under the Endangered Species Act.” The decision came in a brief unsigned order after being reviewed by Chief Judge Roger L. Gregory and judges Stephanie D. Thacker and James A. Wynn Jr.

The case was brought against the pipeline by the Southern Environmental Law Center on behalf of the Sierra Club, Defenders of Wildlife and the Virginia Wilderness Committee.

“Like other agencies, the Fish and Wildlife Service rushed this pipeline approval through under intense political pressure to meet developers’ timelines,” SELC attorney D.J. Gerken said via email. “It’s foolish and shortsighted to risk losing rare species for an unnecessary and costly pipeline boondoggle.”

A spokeswoman for Dominion, which is leading a coalition of companies in building the massive project, said the decision affects only certain areas along the route where specific species have been identified.

“We remain confident in the project approvals and the ACP will continue to move forward with construction as scheduled,” spokeswoman Jen Kostyniuk said via email. She added that “we are continuing to analyze the order and the effects it will have on the project.”

The company will consult with U.S. Fish and Wildlife to revise the limits on harming six particular endangered species, she said. “We will fully comply as required while we continue to construct the project. Although we disagree with the outcome of the court’s decision, and are evaluating our options, we are committed to working with the agency to address the concerns raised by the court’s order.”

The Atlantic Coast Pipeline is one of two such projects being built through Virginia. It starts in West Virginia, crosses into Virginia’s mountainous Highland County and drops down the center of the state to North Carolina.

Kostyniuk said the court’s order will not affect work in North Carolina.

The other project, the Mountain Valley Pipeline, is being built by a separate coalition of companies. That 303-mile project also originates in West Virginia and passes through Virginia’s rugged Southwest.

There are about a half dozen legal challenges to various aspects of the Mountain Valley Pipeline that are pending in federal courts in Virginia and Washington. Similar challenges are playing out against the Atlantic Coast Pipeline.

The Mountain Valley Pipeline has been in the news lately as protesters have staged sit-ins in trees along the route to slow construction. Both projects have been in the tree-clearing stage, and both have been projected to be completed by the end of the year.

Tuesday’s ruling had no impact on the Mountain Valley Pipeline, and it was unclear how much of a disruption it might be for the Atlantic Coast Pipeline. The judges said they would explain their reasoning in a forthcoming opinion.

Opponents have castigated Virginia state environmental agencies, saying they deferred to federal entities and failed to give both projects a full review. Though the state Department of Environmental Quality has said that both pipelines were subjected to the most thorough scrutiny of any such projects, the agency has opened a 30-day comment period for the public to weigh in on whether more needs to be done.

Gov. Ralph Northam (D) has said that he sympathizes with protesters concerned about the environment and property rights but that state and federal agencies must be allowed to follow protocol and evaluate the projects based on scientific review.