More than 100 local and environmental groups are demanding federal regulators immediately halt all construction on Energy Transfer Partners’ Rover gas pipeline after a series of environmental violations, including a massive spill that fouled sensitive wetlands in Ohio with several million gallons of construction mud.

The groups’ concerns go beyond the Rover pipeline. They also urged federal officials to “initiate an immediate review of horizontal drilling plans and procedures on all open pipeline dockets.”

“We think that FERC’s review process has been delinquent so far and not thorough enough, both on this issue with respect to the horizontal drilling practices and other construction processes, but also on broader environmental issues, as well such as the climate impacts of the pipelines like Rover,” said David Turnbull, campaigns director for the research and advocacy group Oil Change International, one of 114 groups that signed a letter sent to the Federal Energy Regulatory Commission on Wednesday.

FERC last week ordered Energy Transfer Partners to not start construction at any new sites along the pipeline route following the spill. The federal officials also halted construction at the spill site and ordered the company to hire an independent contractor to assess what went wrong there. Besides the damaged wetlands, which state officials say could take decades to recover, the project racked up seven other state violations during the first two months of construction.

“While we welcome the Federal Energy Regulatory Commission’s recent action to halt new horizontal directional drilling on the project, it is clear that this limited action is not sufficient to ensure the safety of communities along the pipeline route,” the groups wrote in their letter.

The letter was signed by local green groups in Ohio, such as Ohio River Citizens’ Alliance and the Buckeye Environmental Network, and in neighboring states impacted by the Rover gas pipeline, including West Virginia and Pennsylvania. Many other state and national environmental groups were also signatories.

FERC declined to comment on the letter. “It is FERC policy not to comment on matters pending decision by the Commission of by FERC staff,” spokesperson Tamara Young-Allen wrote in an email to InsideClimate News. Energy Transfer Partners did not immediately respond to a request for comment.

Energy Transfer Partners, which also built the controversial Dakota Access oil pipeline, started construction in late March on the approximately $4.2 billion Rover pipeline project. The project is slated to deliver gas from processing plants in West Virginia, Pennsylvania and eastern Ohio across parallel 42-inch pipes to a delivery hub in northwestern Ohio.

The Rover project triggered its first violation on March 30 after the builders burned debris less than 1,000 feet from a home near the town of Toronto. A couple of weeks later, on April 13, the company released “several millions of gallons” of thick construction mud laced with chemicals into one of Ohio’s highest quality wetlands. This spill happened while the company was using horizontal drilling to help carve out a path underground to lay down the pipe.

Cleanup at the spill site is ongoing, and members of Ohio’s Environmental Protection Agency and FERC are monitoring it. Ohio EPA officials have proposed a $431,000 fine for the Rover project’s violations over its first two months.