In what’s been a tumultuous stretch for Appalachian infrastructure projects, the U.S. Army Corps of Engineers has indefinitely suspended Mountain Valley Pipeline LLC’s (MVP) Nationwide Permit (NWP) 12 verifications until it determines whether there are violations of the water quality certification in West Virginia.

Without the authorizations, the project can’t discharge dredged and fill material into four rivers in the state and must cease all construction activity at those crossings. MVP has not provided an update on what exactly the suspension means for the project’s timeline.

The suspension, issued on May 22, came about a month after West Virginia regulators cited the project for failing to control erosion. It also came the same day a coalition of environmental groups filed a motion in the U.S. Court of Appeals for the Fourth Circuit to stay construction of MVP while the groups challenge the Section 404 permit issued by Army Corps. The groups argue that the project can’t meet conditions that require finishing stream crossings within 72 hours.

The NWP 12 is issued under Section 404 of the federal Clean Water Act and allows contractors to trench through the bottom of streams and rivers.

Meanwhile, more than two dozen trade organizations and unions have come together urging Virginia Gov. Ralph Northam to help protect the NWP 12 verifications for a similar project, the Atlantic Coast Pipeline (ACP). In a letter to the governor, the groups encouraged him to tell the state Department of Environmental Quality (DEQ) to reaffirm the Army Corps permits issued last year. The Virginia State Water Control Board recently directed the DEQ to open a new public comment period on the NWP 12, which the groups said could delay the project or inflate its costs.

ACP would traverse West Virginia, Virginia and North Carolina to transport 1.5 Bcf/d of natural gas to the Southeast. Backers are targeting a 2019 in-service date. MVP would follow a similar path to move 2 Bcf/d to the Southeast, with a targeted late 2018 in-service date.

Challenges against the Army Corps’ permits for the projects came after a federal court this month rejected FERC’s motion to suspend a petition for review of the certificate authorizing MVP, clearing the case brought by environmental groups to move forward. The Fourth Circuit also has vacated ACP’s incidental take permit, which helps protect endangered and threatened species, stopping some construction along a small portion of the pipeline’s proposed 600-mile route.

Environmental groups and other opponents have been doubly concerned about the projects given that they’re crossing hundreds of miles to serve similar purposes. Echoing those concerns, the Federal Energy Regulatory Commission approved them in a rare split decision with Commissioner Cheryl LaFleur dissenting.

On the other side of the basin, in an unrelated development that capped what’s been a difficult month for Appalachian gas infrastructure projects, Pennsylvania regulators again shut down operations on the Mariner East (ME) 1 pipeline and ordered construction on a small stretch of the ME 2 and 2X projects in the southeast part of the state halted over safety issues that were raised by a state lawmaker.