Severe drought is exacerbating concerns about the construction of the Line 3 oil pipeline across northern Minnesota, with the project moving millions of gallons of water even as river and lake levels sink.

DFL lawmakers are now asking state pollution regulators to halt all drilling along the pipeline route until the drought ends and the region's numerous wetlands and rivers recover and can better dilute and flush any chemicals and sediment from the work.

They also don't want drilling to resume until the state has investigated nine drilling mud spills along the construction route this summer, according to a July 27 letter to Minnesota Pollution Control Agency (MPCA) Commissioner Peter Tester signed by 32 DFL lawmakers.

The lawmakers asked for detailed information on the nine incidents, which they said were violations of a water quality permit the MPCA issued to Calgary-based Enbridge for the project. They asked for the dates and locations of the incidents, for example, as well as the amounts of drilling fluid and bentonite clay released, the distance of spills to nearby waters or wetlands, and information on cleanup measures.

Permit violations

Minnesota's drought is particularly severe in the pipeline area, said Rep. Frank Hornstein, DFL-Minneapolis. Upper Rice Lake, a shallow lake in Clearwater County near the headwaters of the Mississippi River, is so low "you can walk on the lake bottom, it's that bad," he said.

The lake is not far from where Enbridge crews are working as they tunnel about 60 feet beneath the Mississippi River. Construction of the 340-mile pipeline across Minnesota is more than 70% complete.

"This permit was touted as restrictive, and now we've had at least nine violations," Hornstein said. "Is the system even working?"

MPCA spokesman Darin Broton said the agency is investigating all nine "frac-outs or inadvertent releases" of drilling mud. Only one was directly on a waterway — Willow River in Aitkin County. That spill was discovered July 6. About 80 to 100 gallons of drilling mud were released. Several other spills were in wetlands, such as the Mississippi Headwaters, which is also a violation, Broton said.

"Some of these sites may have multiple violations but we're still investigating," he said.

Water Protectors activists reported a spill July 20 in a marsh on the Mississippi River in Clearwater County.

At issue is the 401 water quality certification under the Clean Water Act, administered by the MPCA, that requires projects to not pollute the water and comply with standards.

Broton said the agency appreciates the questions from legislators.

"There has been a lot of misinformation on social [media] in the past few weeks," he said. "We have tried to debunk the misinformation while not undermining an active enforcement investigation.

"We look forward to sharing more information with legislators in the coming days and weeks," Broton said.

Enbridge spokeswoman Juli Kellner said the drought is concerning and the company is trying to protect and conserve water.

"In eight of the nine instances, drilling mud was contained entirely on land and cleaned up," Kellner said. "In the case of the Willow River there were no impacts to any aquifers nor were there downstream impacts because environmental control measures were installed at the location."

Kellner said drilling fluid, or drilling mud, is nontoxic and made up mostly of bentonite clay and water.

The company is currently engaged in horizontal drilling at more than a dozen sites where it is tunneling beneath water bodies.

Billions of gallons

Drought concerns reared in June when the state Department of Natural Resources (DNR) amended Enbridge's water appropriation permit to allow the company to pump nearly 5 billion gallons of groundwater that seeps into the construction trenches. The company discharges the pumped water elsewhere. That's nearly 10 times the amount previously permitted.

In July, the DNR started restricting Enbridge's pumping of surface water from lakes and rivers for things such as dust control and horizontal drilling, due to the dry conditions. The regulator has temporarily suspended pumping from more than two dozen locations on creeks, rivers and lakes across multiple watersheds.

The DNR said the 5 billion gallons of groundwater would not be drawn from one location but spread out along the construction line, and the effects last only a few days.

"It really has very limited effect on surface water features or river flow," said Randall Doneen, the DNR's manager of conservation assistance and regulations.

DFL lawmakers wrote to the DNR and MPCA about that matter, too, in June saying they want more information about how Enbridge intends to abide by the requirements of the statewide drought plan.

Alarmed by the 5 billion gallon water appropriation, dozens of scientists also wrote to Gov. Tim Walz and President Joe Biden on July 20. They said the appropriation was made without consulting with affected Native American tribes, and that it is "one of the largest, if not the largest, appropriation of water from Minnesota's shallowest surficial aquifers in the last 30 years."

Jennifer Bjorhus • 612-673-4683

Correction: Earlier versions of this story misstated when the DNR started restricting surface water pumping.