A permit for the Atlantic Coast Pipeline to cross two national forests, including parts of the Appalachian Trail, was thrown out Thursday by a federal appeals court that harshly criticized regulators for approving the proposal.

A three-judge panel of the 4th U.S. Circuit Court of Appeals in Richmond blasted the U.S. Forest Service for granting a special use permit to build the natural gas pipeline through parts of the George Washington and Monongahela National Forests, and granting a right of way across the Appalachian Trail.

"A thorough review of the record leads to the necessary conclusion that the Forest Service abdicated its responsibility to preserve national forest resources," Judge Stephanie Thacker wrote for the panel in the unanimous ruling.

The court said the agency had "serious environmental concerns" about the project that were "suddenly, and mysteriously, assuaged in time to meet a private pipeline company's deadlines."

The ruling also quoted "The Lorax" by Dr. Seuss, saying the Forest Service is trusted to "speak for the trees, for the trees have no tongues."

Aaron Ruby, a spokesman for Dominion Energy, the project's lead developer, said the developers "strongly disagree" with the court's ruling and plan to immediately appeal by seeking a hearing before the full 4th Circuit court.

"If allowed to stand, this decision will severely harm consumers and do great damage to our economy and energy security," Ruby said in a statement. "Public utilities are depending on this infrastructure to meet the basic energy needs of millions of people and businesses in our region."

The ruling came in a lawsuit filed by the Southern Environmental Law Center on behalf of the Sierra Club, Virginia Wilderness Committee and other environmental groups. Patrick Hunter, a staff attorney for the center, said the ruling is a "huge problem" for Dominion.

"Their whole route is designed to cross the Appalachian Trail at this one location," Hunter said.

"That means this pipeline — as they've designed it — is not a viable project at this point."

The 605-mile natural gas pipeline would originate in West Virginia and run through parts of North Carolina and Virginia.

The 4th Circuit said the Forest Service did not have the statutory authority to grant the right-of-way to cross the trail between Augusta and Nelson counties.

Ruby said the court's ruling is "at odds" with the U.S. Department of Interiors, the U.S. Department of Agriculture, National Park Service and U.S. Forest Service.

"All of these agencies agree that the Forest Service has the full legal authority to approve the Atlantic Coast Pipeline's crossing of the Appalachian Trail," Ruby said.