Measures are used to contain up to 1,900 gallons of bentonite clay, or drilling fluid, that flowed Saturday from Enbridge’s Line 5 reroute project into a forested wetland in Wisconsin’s Iron County. (Photo courtesy of Earthjustice via the Bad River tribe)

Crews spilled up to 1,900 gallons of drilling fluid Saturday as they were working on Enbridge’s Line 5 reroute in northern Wisconsin.

The Canadian energy firm notified the Wisconsin Department of Natural Resources about the release that occurred about 4:30 p.m. Saturday in the Iron County town of Gurney, Wis. The company contracted with Michels Pipeline Inc. to install a new 41-mile stretch of pipeline around the Bad River tribe’s reservation.

The spill is known as an inadvertent return or unintentional release of drilling fluid that’s often called a “frac-out.” In an email obtained by Wisconsin Public Radio, Elizabeth Romfoe, the DNR’s northern region spill coordinator, relayed details of the incident to the tribe’s brownfield specialist Grant Whitman.

“The estimated volume released is 1500-1900 gallons of the bentonite clay, mostly in the forested wetland. About 5-8 gallons entered Vaughn Creek,” Romfoe wrote.

Romfoe said the clay was removed from the creek in roughly an hour and measures were used to contain the spill within the wetland. In a statement, a DNR spokesperson said it had verified the amounts of the spill reported, and Enbridge is working to remove drilling fluid from the wetland.

Pipes staged for the Enbridge Line 5 reroute in Wisconsin’s Iron County. (Danielle Kaeding/Wisconsin Public Radio)

Bad River Tribal Chairwoman Liz Arbuckle said the spill is what she feared.

“They (Enbridge) have talked repeatedly about how safe they are, and here we are a month or so into this project, and we’ve already got this,” Arbuckle said.

Enbridge spokesperson Juli Kellner confirmed in an email that it reported the release Saturday of a “clay and water mixture” that’s approved for horizontal directional drilling by the DNR.

“Following preapproved response plans, the release has been contained using sandbags and silt fence to protect the creek during the clean-up, which is well underway,” Kellner said. “We will continue to work with the DNR on completion of the clean-up.”

The tribe and environmental advocates argue Enbridge violated the waterway and wetland permit the DNR issued in 2024. Among its 250 conditions, the agency stated the company “shall not discharge drilling mud into wetlands, waterways or sensitive areas.” Drilling mud is created by mixing water and clay.

Crews working on Enbridge’s Line 5 reroute spilled up to 1,900 gallons of drilling fluid into a forested wetland in Wisconsin’s Iron County on Saturday. (Photo courtesy of Earthjustice via the Bad River tribe)

The company has said Brownsville-based Michels is leading work on the $450 million project along with subcontractors from the Ashland area and Wisconsin. Enbridge previously said about 500 workers are on site, and the project is expected to support 700 jobs at peak construction.

The project crosses about 101 acres of wetlands and 186 waterways. Drilling, digging and blasting will directly occur in about 70 water crossings.

Arbuckle said she first learned of a potential spill from Bad River tribal elder Joe Bates. He had raised concerns about possible violations near Vaughn Creek after capturing drone footage on June 23. He said the video shows drill fluid that had flowed outside of the drilling area, but the DNR found the release occurred in an approved area.

“My concern is that it’s leaching into the water,” Bates said, fearing it may contaminate the aquifer or drinking water.

The spill comes as the tribe and environmental groups continue to challenge state permits issued for the project in Iron County Circuit Court, seeking to halt construction. They had previously challenged those approvals in a weekslong contested case hearing, but an administrative law judge upheld the permits in February.

In May, a Bayfield County judge appointed to the case allowed most work to continue, but he halted construction in four waterways where the company needs additional permits.

Skylar Harris, climate justice fellow for Midwest Environmental Advocates, said the incident highlights why they’ve taken legal action over permits for the Line 5 reroute.

“These kinds of spills, what Enbridge and DNR are calling inadvertent releases, they’re not simply an unfortunate accident,” Harris said. “These are the exact kind of disastrous incidents our clients have warned about, and these risks were identified throughout the permitting process by Enbridge and DNR, but they still allowed those permits to move forward.”

In total, the DNR said it’s issued two notices of noncompliance to Enbridge since March that don’t include the recent spill, and the company remedied two other issues identified by the DNR. The agency said three independent environmental monitors are on staff at all times when the company is working on the project. They operate under the direction of the agency and report directly to the DNR.

Arbuckle said the DNR should take enforcement action against Enbridge, and she’d like the court to freeze construction. She worries about the potential for more spills into waterways that flow through the reservation or Lake Superior.