The last Dakota Access Pipeline protesters march out of the Oceti Sakowin camp in February, just before the deadline set for evacuation by the U.S. Army Corps of Engineers . (Mike McCleary/Bismarck Tribune via AP)

The same company that built the controversial Dakota Access oil pipeline has twice spilled drilling fluids in two pristine Ohio wetlands this month while constructing a $4.2 billion natural gas pipeline that will stretch from Appalachia to Ontario, Canada.

The drilling fluid — a mudlike substance used to lubricate and cool equipment — is not toxic. But the Ohio state Environmental Protection Agency and environmental groups were worried that the larger of the two spills, which covered a vast area the size of 8½ football fields, could smother aquatic life in the wetlands.

Energy Transfer Partners notified the Ohio EPA that it spilled as much as 2 million gallons of drilling mud and cuttings from underground on April 13, affecting an area 1,000 feet long and 500 feet wide south of the town of Navarre.

And on April 14, it spilled 50,000 gallons of the same fluids, affecting a smaller area of 30,000 square feet near Mifflin Township more than 100 miles away.

Both incidents happened during the construction of the Rover pipeline, a 710-mile project that includes 207 sensitive water crossings. Energy Transfer was drilling horizontally under the crossings.

The spills aren’t the only spots of controversy for the Rover pipeline.

Last year, the Federal Energy Regulatory Commission referred the company to its enforcement division for possible penalties after Energy Transfer Partners bought and then demolished a house that dated back to 1843 and which was under consideration for inclusion in the National Register of Historic Places.

The house, which was across the street from one of Rover’s proposed compressor stations, had been singled out in the company’s pipeline permit application as part of its environmental impact statement, and FERC said that “Rover demolished the structure with no prior notice or forewarning” even though “Commission staff identified the Stoneman House as an issue of concern early-on during the pre-filing process.”

FERC said “Rover had intentionally and adversely affected the historic property.”

Energy Transfer Partners has also been in the political limelight. Its chief executive Kelcy Warren has given heavily to Republican candidates and political action committees. Its board of directors included Rick Perry, who resigned Dec. 31 after he was nominated to become energy secretary. And Donald Trump was an investor, but his lists of stock holdings indicate that he sold his shares.

The company has asserted that there is no danger from the spills. It said in a statement that the drilling mud is made of bentonite and “is a nontoxic, naturally occurring material that is safe for the environment.”  It said the chemical is used in household products such as sugar, honey, creams, lotions, laundry detergents and hand soaps.

The company said that the drilling mud “was able to migrate through naturally occurring fractures in the soils and reach the surface. It is important to note this is a common and normal component of executing directional drilling operations [and] there will be no impact to the environment,” the company said in the statement.

But the Ohio state EPA said the spill posed a danger to some of Ohio’s last surviving wetlands.

“Discharges of bentonite mud and other material into waters of the state (including wetlands) can affect water chemistry, and potentially suffocate wildlife, fish and macroinvertebrates,” said Ohio EPA spokesman James Lee.

Jen Miller, Ohio director of the Sierra Club, said the incident was “confirming our worst fears about this dangerous pipeline before it has even gone into operation.”

Calling for a halt in construction, she said in a statement that “we’ve always said that it’s never a question of whether a pipeline accident will occur, but rather a question of when.”

At the larger spill site, Energy Transfer Partners, has erected a barrier to keep the material from leaking into the nearby Tuscarawas River and has been using vacuums to clean up the spill, according to the state EPA.

Lee said the agency would consider possible fines after the company finished cleaning up the area. But the state EPA can impose fines of just $10,000 or $25,000 a day, depending on the violation, a tiny amount in the cost of the project.

It’s much more important for the company, which already owns and operates 71,000 miles of oil and gas pipelines, to finish the project on time.

Energy Transfer has told investors and customers desperate for more pipelines out of the gas-rich Marcellus shale region that much of the line would be in operation by July, and it would be fully in operation by November.

The portion of the line slated to be in service this summer — ending in a hub near Defiance, Ohio — would transport about 2 billion cubic feet a day. Prices vary, but at a 60 cent a thousand cubic feet rate that would bring $1.2 million a day.

Ultimately the pipeline would transport to Michigan and Ontario for a total of 3.25 billion cubic feet a day and generate $2 million to $3 million a day, according to industry experts.

FERC has not ruled on another pipeline that would serve producers in the Marcellus shale region.

The regulator lacks commissioners to make up a quorum and cannot approve new projects until President Trump nominates new members. Those members must also be confirmed by the Senate.

Ohio lost the bulk of its wetlands more than a century ago as settlers and farmers drained and developed the Great Black Swamp that stretched across the northeast portion of the state.

“We’ve been trying to make sure we protect all our wetlands, even the lower quality ones. They provide a whole suite of functions,” said Kristy Meyer of Ohio Environmental Council, a nongovernment group.

Ohio EPA’s Lee said that the affected area was a flood plain wetland that serves as a buffer between nearby farms and the Tuscarawas River.

He said the spill affected less than half of the wetland at the site, and that most of the higher quality areas did not immediately appear to be affected.