The U.S. Army Corps of Engineers has filed a motion to lift the stay of verifications it issued for a crucial water crossing permit for the Mountain Valley Pipeline (MVP) project, arguing that it’s addressed the issues involved.

The U.S. Court of Appeals for the Fourth Circuit last month granted a motion to stay the Nationwide Permit (NWP) 12 issued by the Army Corps pending a ruling on a legal challenge brought by a coalition of environmental groups including the Sierra Club.

The NWP 12 is issued under Section 404 of the U.S. Clean Water Act (CWA) and allows contractors to trench through the bottom of streams and rivers. The Sierra Club earlier this year challenged the validity of MVP’s NWP 12 permit, arguing that the project could not meet a special state-specific condition in West Virginia requiring all stream crossings be constructed within 72 hours.

In response to the challenge, the Army Corps voluntarily issued a limited suspension of the NWP 12 for four river crossings in West Virginia. But the Sierra Club and others successfully argued to the court that under Army Corps regulations, all portions of the NWP 12 permit must be stayed, putting nearly 600 MVP waterbody crossings in regulatory limbo.

Earlier this month, the Army Corps completed an administrative review, issued a reconsideration letter covering the original verifications and lifted suspension of the NWP 12 at the four river crossings in West Virginia. The agency also imposed additional environmental protections for construction.

The “new decision constitutes changed circumstances that justify relief from the court’s previous stay,” the Army Corps said in its motion, adding that the court no longer has jurisdiction to consider petitioners’ challenge to the original verifications. That challenge was the only “substantive basis for a stay,” and now that it has been addressed within the agency’s authority under the CWA, the environmental groups are no longer likely to succeed.

The Sierra Club’s argument that MVP would not be able to comply with the original permit condition only applied to water crossings constructed in an open trench while the river is flowing, or a wet-cut method. MVP now plans to use a more time-consuming dry-ditch, cofferdam method to cross the rivers and better protect the environment, a decision the Army Corps cited in lifting the suspension and replacing the original verifications document.

MVP said if the stay is left in place pending the legal challenge, it could cost millions and delay the project for nearly one year. The project is currently targeting an in-service date of 4Q2018.

The 300-mile pipeline would move 2 Bcf/d from West Virginia to Virginia and connect with the Transcontinental Gas Pipe Line to move more Marcellus and Utica shale volumes to Southeast markets. The project, along with the similarly routed Atlantic Coast Pipeline, has faced staunch opposition.

Sierra Club said Friday a volunteer organization of concerned residents launched an online map that details dozens of alleged water quality violations along the MVP route that have occurred during construction.