Energy Transfer Partners, the company behind the controversial Dakota Access oil pipeline, is under fire from federal and state regulators after triggering a massive spill, and seven other violations, during the first seven weeks of construction of a major gas pipeline in Ohio.

The Federal Energy Regulatory Commission (FERC) on Wednesday sent a letter to the Rover pipeline operator ordering it to not start construction on any new locations, as well as to stop construction at the site of the major wetlands spill and to hire an independent contractor to dig into what went wrong there.

"Staff has serious concerns regarding the magnitude of the incident (which was several orders of magnitude greater than other documented [horizontal directional drilling] inadvertent returns for this project), its environmental impacts, the lack of clarity regarding the underlying reasons for its occurrence, and the possibility of future problems," federal regulators wrote. The phrase "inadvertent returns" is industry speak for a certain type of spill or release of construction material.

The FERC letter came less than a week after the Ohio Environmental Protection Agency proposed a $431,000 fine for violations and ordered the company to immediately implement its emergency response plan.

The same day the Ohio EPA reached out to the pipeline builder, it also asked FERC to step in. That's because state officials had previously encountered pushback from the company, which had argued that only federal regulators had jurisdiction to take action. The company also planned to restart drilling at the site of the big wetlands spill that day.

"In light of Rover's restarting drilling operations and Rover's position that the state is without any authority to address violations of environmental laws, we are asking FERC to review the matter and to take appropriate action in the most expeditious manner to ensure that Rover is held responsible for the violation and is conducting its ongoing drilling operations to ensure protection of human health and the environment," Ohio EPA director Craig Butler wrote to FERC.

Energy Transfer Partners' about $4.2 billion Rover project is expected to transport gas from processing plants in West Virginia, Pennsylvania and eastern Ohio across twin 42-inch pipelines to a delivery hub in northwestern Ohio.

Construction started around March 24, and the first violation occurred on March 30, involving the burning of construction debris less than 1,000 feet from a home near Toronto, Ohio, according to the Ohio EPA compliance letter to the company from May 5.

An additional 17 incidents, seven of which resulted in violations, had occurred at various construction sites across the state by May 7. State officials said they learned of some of the incidents through the company and others through calls from the community.

The worst violation was on April 13 and involved the release of "several million gallons" of what's called "bentonite slurry"—thick mud laced with chemicals used to help drill underground to create space for laying down pipe—into some of the state's highest quality wetlands. The mud coated the wetlands, smothering vegetation and aquatic life in an ecosystem that helps filter water between farmland and nearby waterways.

Even after the surface spill was discovered, the company restarted construction there. This is the one site where cleanup is still ongoing. Both state and federal officials are monitoring the situation.

"Ohio EPA believes it's going to be decades before that wetland can be restored to its previous condition," agency spokesman James Lee told InsideClimate News.

Alexis Daniel, a spokesperson for Energy Transfer Partners, confirmed in an email to InsideClimate News that construction had stopped at the wetlands site.

"We are working with the FERC and the OEPA to resolve these issues in a manner that is satisfactory to everyone involved, and most importantly ensures the complete remediation of these areas," Daniel said.

Sierra Club's dirty fuels organizer Cheryl Johncox, however, is skeptical about the company's compliance efforts. She said: "They don't have a clue what they are doing or they just don't care. This is represented by two things: the number of violations within a short period of time and their flippant attitude towards the Ohio EPA."

The company has also run into recent problems on the Dakota Access pipeline, which drew months of protests over its planned route near the Standing Rock Reservation and concerns over safety for the reservation's water supply. The pipeline leaked 84 gallons of crude oil at a South Dakota pump station in April.