The two biggest U.S. natural gas pipelines under construction are likely facing more delays after an appeals court ruling against the Army Corps of Engineers, energy analysts said.

The Trump administration has pressed ahead with new pipeline construction but several projects have been stalled by successful legal challenges saying the administration is not applying careful regulatory scrutiny.

Last month, a Montana judge ruled the Army Corps authorized permits to cross streams without properly consulting other federal agencies on endangered species. Rather than limit its ruling to the Keystone XL crude pipeline case before the court, the judge questioned the Army Corps’ method of authorizing stream crossing under the entire National Permit 12 program.

The U.S. Ninth Circuit Court of Appeals on May 28 left that ruling in place, which will likely prevent Keystone and other pipelines from using Army Corps’ stream crossing permits until the appeals court decides in early 2021, the analysts said.

It means the two biggest gas pipes under construction—Dominion Energy Inc.’s Atlantic Coast and EQM Midstream Partners LP’s Mountain Valley—are likely to be delayed by several more months.

Mountain Valley is not likely to start service until at least second-quarter 2021, analysts at Height Capital Markets in Washington said on May 29.

“There are too many variables regarding the ... recent Ninth Circuit ruling to accurately determine the potential impact to Mountain Valley’s schedule or budget at this time,” said EQM spokeswoman Natalie Cox. The current in-service target for the $5.4 billion West Virginia-Virginia pipeline is still late 2020, she said.

Dominion said it was disappointed in the court’s decision but still planned to complete the $8 billion Atlantic Coast from West Virginia to North Carolina in early 2022, so long as it can cut trees from November to March.

Height Capital analysts, however, said “Dominion will also likely need to push in-service for Atlantic Coast as this decision will impact (its) ability to clear trees.”