Updated: March 22, 7:20 a.m.
The Minnesota Department of Natural Resources has released details of more groundwater leaks caused by the construction of the Line 3 oil pipeline last year.
The DNR has completed its investigation of three sites where crews installing the pipeline breached underground aquifers, causing uncontrolled — and unauthorized — flows of groundwater.
State regulators previously identified one of the three locations, near Enbridge’s Clearbrook terminal. In January 2021, crews installing the replacement pipeline dug deeper than planned, piercing the top layer of an aquifer under pressure.
Enbridge reported that flow was stopped nearly a year later, after releasing at least 50 million gallons of groundwater.
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The DNR now says a second breach occurred around Aug. 2 near LaSalle Creek in Hubbard County, and released about 9.8 million gallons of groundwater before Enbridge reported it had stopped the flow four months later.
A third breach was identified around Sept. 10 near the Fond du Lac Band of Lake Superior Chippewa reservation in St. Louis County, when groundwater began welling up as crews removed sheet piling after finishing construction on that stretch of pipeline.
The DNR said Enbridge has substantially slowed — but not completely stopped — that leak, which has resulted in the release of nearly 220 million gallons of groundwater. The agency said the breach potentially could affect nearby Dead Fish Lake, an important wild rice water for the Fond du Lac Band.
State regulators ordered Enbridge to stop the groundwater flows and restore the sites. The company already has paid more than $3 million for the violations, and could face additional penalties.
In a statement released Monday, Enbridge said they regret the breaches and "are taking steps to improve our procedures to prevent this type of occurrence in the future. We are dedicated to resolving these matters quickly and thoroughly as we continue to work with the regulatory agencies on the ongoing restoration and monitoring at all three sites.”
An Enbridge spokesperson said the vast majority of the water discharged at all three sites was returned nearby, while a small amount was removed for treatment.
The DNR said it has investigated whether other aquifer breaches occurred along the Line 3 route, but has not confirmed any other breach sites. The agency said it will complete its final assessment following the spring thaw.
In a press release, the Fond du Lac Band said the breach is discharging water within the reservation boundaries upstream of Dead Fish Lake. It said the flow potentially could violate the Band's water quality standards and impact its natural resources, including one of its wild rice waters.
The Fond du Lac Band adopted “stringent” water quality standards in 1998 that surpass the state's, the release stated. "These water quality standards prompted decades of specialized, technical investment in stewarding our cultural and natural resources; the breach's hydrologic alteration could threaten that work," it stated.
The 340-mile replacement pipeline, which follows a partly new route across northern Minnesota, began pumping crude oil last fall.