The U.S. Supreme Court says the Forest Service can grant a right-of-way for a gas pipeline across the Appalachian Trail/NPS file

Editor's note: This updates with reaction from the National Parks Conservation Association.

In a 7-2 ruling Monday the U.S. Supreme Court said an energy company could run a gas pipeline across the Appalachian National Scenic Trail in Virginia, holding that the National Park Service controls just an easement to the land traversed by the iconic foot path without authority to block the project.

Key was whether the Mineral Leasing Act, a many-times-amended law passed in 1920 that allows for the leasing of public lands for developing energy, applies to lands in the National Park System, and whether the A.T. itself qualifies as "lands" within the system.

The case was titled United States Forest Service et al. vs. Cowpasture River Preservation Association et al. It had reached the U.S. Supreme Court after a unanimous 4th U.S. District Court of Appeals in December 2018 ruled that the Forest Service lacked the authority to OK construction of the Atlantic Coast natural gas pipeline across the Appalachian Trail, or any lands managed by the National Park Service, for that matter. 

Last June the company behind the pipeline, Dominion Energy's Atlantic Coast Pipeline, LLC, asked the Supreme Court to review the lower court's ruling.

The majority opinion (attached below), written by Justice Clarence Thomas, said the Park Service held only an easement for the A.T. through the George Washington National Forest, while the U.S. Forest Service still controlled how the land was used and so under the Mineral Leasing Act could grant the right-of-way.

"...the lands that the Trail crosses are still 'Federal lands,' and the Forest Service may grant a pipeline right-of-way through them—just as it granted a right-of-way for the Trail," Thomas wrote. "Sometimes a complicated regulatory scheme may cause us to miss the forest for the trees, but at bottom, these cases boil down to a simple proposition: A trail is a trail, and land is land."

But in their dissent, Justices Sonia Sotomayor and Elena Kagan argued that the National Trails System Act did indeed give the Park Service authority to manage the A.T.'s surface and subsurface.

"The Trails Act provides that the Secretary of Interior has authority to 'grant easements and rights-of-way' among other things, 'under' the Appalachian Trail's surface," wrote Sotomayor. "In 1969, the Secretary of the Interior assigned all these powers to the Park Service, naming it the Trail's 'land administering bureau.' Since then, the Federal Government has consistently identified the Trail as a 'unit' of, and thus land in, the National Park System. 

"By statutory definition, the Appalachian Trail is land in the National Park System, and the Mineral Leasing Act does not permit rights-of-way across it."

Justices Sotomayor and Kagan maintained that both the National Park Service Organic Act and the National Trails System Act "confirm that the Trail is land, land on which generations of people have walked."

"Indeed, for 50 years the 'Federal Government has referred to the Trail' as a 'unit' of the National Park System. A 'unit' of the Park System is by definition either 'land' or 'water; in the Park System," they went on. "Federal law does not distinguish 'land' from the Trail any more than it distinguishes 'land' from the many monuments, historic buildings, parkways, and recreational areas that are also units of the Park System. Because the Trail is land in the Park System, 'no federal agency' has 'authority under the Mineral Leasing Act to grant a pipeline right-of-way across such lands."

The court's majority, though, held that the Weeks Act, which "states that lands acquired for the National Forest System -- including the George Washington National Forest -- 'shall be permanently reserved, held, and administered as national forest lands,'" governed the matter.

"We hold that the Department of the Interior's decision to assign responsibility over the Appalachian Trail to the National Park Service did not transform the land over which the Trail passes into land within the National Park System," wrote Justice Thomas. "Accordingly, the Forest Service had the authority to issue the permit here."

Furthermore, according to the majority opinion, construction of the pipeline corridor will not directly impact the A.T. The pipeline will pass roughly 600 feet beneath the trail, with construction entry and exit points located 1,400 feet and 3,400 feet from the trail, the opinion noted.

While the court's majority said Atlantic Coast Pipeline does not need to clear any land or "dig on the Trail's surface," Sotomayor and Kagan wrote that the plan "calls for 'clearing trees and other vegetation from a 125-foot right of way (reduced to 75 feet in wetlands) through the national forests, digging a trench to bury the pipeline and blasting and flattening ridgelines in mountainous terrains.'

"Construction noise will affect the Appalachian Trail 24 hours a day. Atlantic's machinery (including the artificial lights required to work all night) will dim the stars visible from the Trail."

The dissenting justices also noted that the appellate court had found that the construction plan "may conflict with several environmental laws, including the National Forest Management Act and the National Environmental Policy Act. Those aspects of the Fourth Circuit's decision are not before this Court."

Mark Burghardt, a partner at the international law firm Dorsey & Whitney in its oil and gas industry group, applauded the majority opinion.

"Long term, it allows pipeline companies to plan pipeline routes with certainty on how to cross the 780-mile-long Appalachian Trail (that runs through national forest lands) and will allow the development of natural gas fields in less-populated areas to the west," he said. "The environmental groups challenging the pipeline were not worried about damage to the trail, since this pipeline is located far underground. These groups are simply against fossil fuels, notwithstanding their stated goals. This decision is a huge blow to their cause.

"... The lower court’s ruling would essentially create a barrier along a large portion of the East Coast to moving hydrocarbons from where they are produced to where they are used. This consequence could not have been intended by Congress in enacting the Trails Act," he added from his Denver office.

At the National Parks Conservation Association, President and CEO Theresa Pierno condemned the ruling.

"Dominion Energy is on the verge of building a pipeline underneath the Appalachian National Scenic Trail, and today’s Supreme Court ruling only makes it easier for them. This ruling flies in the face of underlying federal laws intended to protect parks from this exact kind of threat," she said. "Federal agencies are prohibited by law from granting pipeline crossings across lands in the National Park System.

“The Appalachian Trail welcomes millions of hikers each year. People come from all over the world to enjoy more than 2,000 miles of trail, offering one-of-a-kind respite from the stresses of daily life. This project threatens their unique visitor experience, along with priceless mountain streams and clean air," she added. "While the pipeline still requires a number of other permits to move forward, which are themselves being challenged in court, we are disappointed by the court’s decision. It fails to honor the commitment made to the American public to protect special places by designating them as units of the National Park System.”