Just weeks removed from a victory in the U.S. Supreme Court, Duke Energy and Dominion Energy have abandoned their Atlantic Coast Pipeline project that would have burrowed beneath the Appalachian National Scenic Trail in Virginia.

In a 7-2 ruling on June 15 the high court ruled that Dominion Energy could run a natural gas pipeline beneath the Appalachian Trail, 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.

Despite that victory, the companies announced Sunday that the prospect of additional legal challenges and expenses made the project too expensive. It had initially been expected to cost $4-$4.5 billion to complete, but it ballooned upwards to $8 billion.

...recent developments have created an unacceptable layer of uncertainty and anticipated delays for ACP.

Specifically, the decision of the United States District Court for the District of Montana overturning long-standing federal permit authority for waterbody and wetland crossings, followed by a Ninth Circuit ruling on May 28 indicating an appeal is not likely to be successful, are new and serious challenges. The potential for a Supreme Court stay of the district court's injunction would not ultimately change the judicial venue for appeal nor decrease the uncertainty associated with an eventual ruling. The Montana district court decision is also likely to prompt similar challenges in other Circuits related to permits issued under the nationwide program including for ACP.

"We regret that we will be unable to complete the Atlantic Coast Pipeline. For almost six years we have worked diligently and invested billions of dollars to complete the project and deliver the much-needed infrastructure to our customers and communities," said Dominion Energy Chairman Thomas F. Farrell, II, and Lynn J. Good, Duke Energy chair, president, and chief executive officer.

"Throughout we have engaged extensively with and incorporated feedback from local communities, labor and industrial leaders, government and permitting agencies, environmental interests and social justice organizations," they added. "We express sincere appreciation for the tireless efforts and important contributions made by all who were involved in this essential project. This announcement reflects the increasing legal uncertainty that overhangs large-scale energy and industrial infrastructure development in the United States. Until these issues are resolved, the ability to satisfy the country's energy needs will be significantly challenged."

Environmentalists cheered the company's decision.

“This pipeline was a boondoggle from the moment it was announced by Dominion CEO Tom Farrell and then-Virginia Governor Terry McAuliffe in September 2014. The Chesapeake Climate Action Network is proud to have been one of the first statewide environment groups to take up this cause, to organize our supporters, and to protest with everything from letters to the editor to civil disobedience," said Mike Tidwell, executive director of the Chesapeake Climate Action Network.

The pipeline would have run 600 miles from West Virginia through Virginia to North Carolina.