Enbridge has spilled more drilling mud along the Line 3 construction route in northern Minnesota than previously reported — 28 spills so far this summer, creating at least 10,000 gallons of muck.

State pollution regulators confirmed the totals Tuesday in a response to DFL lawmakers who called for a halt to drilling and demanded an accounting of the spills.

Meanwhile, in a move that has alarmed Line 3 opponents, Enbridge has been buying water from the city of Park Rapids for dust suppression in the weeks since the state restricted the company's use of water from drought-stricken lakes and rivers. The company said it has also used water from Bagley.

The health of the region's water supply has been at the heart of searing controversy surrounding Enbridge's replacement oil pipeline, which is now more than 80% complete. It will carry tar sands oil from Canada 340 miles across northern Minnesota to Superior, Wis.

In a letter Monday to DFL lawmakers, Minnesota Pollution Control Agency (MPCA) Commissioner Peter Tester said the water pollution permit issued to Enbridge doesn't allow it to release drilling fluid "to any wetland, river or other surface waters." He said those spills are "under active enforcement investigation."

The letter also said that the MPCA has increased the number of independent environmental monitors at sites and "required additional containment and response equipment" at active horizontal drilling sites.

For example, the agency now requires fabric barriers called "turbidity curtains" to catch silt and sediment when Enbridge drills beneath rivers.

A memo from Enbridge attached to the MPCA letter lists emergency gear the company has stationed at drilling sites, such as 70 straw bales, 800 sandbags, pumps and a small boat.

Tester said in the letter that information on active investigations isn't public. But the MPCA was releasing some information to dispel "widespread rumor" about the Line 3 on social media.

The letter and attached table detailed 28 inadvertent releases of drilling fluid from June 8 to Aug. 5, with individual spills ranging from 10 gallons to as much as 9,000 gallons. One spill occurred in the Willow River, 13 spills happened in wetlands, and 14 were on land, although in one instance the spill flowed into a wetland.

All the spills involved Barakade Bentonite, a brand name for the sodium bentonite clay base that is mixed with water to create drilling mud, MPCA spokesman Darin Broton said. Many releases also involved one or more additives identified as Power Pac-L and Sandmaster, Power Soda Ash and EZ Mud Gold.

Drilling mud can be considered a pollutant if it enters water, Broton said.

Rep. Frank Hornstein, DFL-Minneapolis, said the DFL legislators group is disappointed the MPCA didn't suspend drilling given that violations "are piling up."

Sen. Mary Kunesh, DFL-New Brighton, said lawmakers met with MPCA staff Monday to discuss the issue.

"If anything, we're more alarmed," she said.

Enbridge's purchase of municipal water from Park Rapids is also raising eyebrows.

Earlier this summer, the state Department of Natural Resources (DNR) restricted the company's water appropriation permits to pump water directly from drought-stricken lakes and rivers. In response, Enbridge turned to trucking in municipal water from Park Rapids.

Scott Burlingame, the city's public works director, said Enbridge has been using three metered hydrants for about six weeks. He said he does not know what Enbridge's final water bill will be, but that the company is being charged the same rate as comparable customers.

"In truth I'd love to charge them more, but we can't," Burlingame said with a laugh. "They get treated the same."

News of the Park Rapids water sales spread after Winona LaDuke posted on Facebook a photo of a contractor's truck filling up.

LaDuke, a member of the White Earth Band of Ojibwe, is a vocal opponent of Line 3 and part of a group called "water protectors" that has demonstrated along the construction route. LaDuke said she planned to ask the Park Rapids City Council about the purchases at a meeting Tuesday evening.

"I'm mad as heck," LaDuke said. "Enbridge is running rogue all over the north with no protection for the environment for Native People or for anything."

LaDuke said Park Rapids residents should have had a say in how their water is used. She also objected to Enbridge using the city water because it comes from deep aquifers that won't quickly recharge from rain and snow. "It takes like 100 years to recharge a deep aquifer, not a season," she said.

Kunesh, meanwhile, called the purchases "very alarming."

DNR spokesman Gail Nosek said Enbridge did not need DNR approval to tap the water because it's "an acceptable source, from an area that isn't subject to a surface water suspension."

The DNR has not altered its earlier decision to allow Enbridge to pump out up to 5 billion gallons of water seeping into construction trenches.

Enbridge spokeswoman Lorraine Little said the company has vowed to protect and conserve water along Line 3 and is working with regulators.

"We have used about 830,000 gallons of water from Park Rapids since June 21st, mainly for dust suppression," she said. "We have also used water from the city of Bagley."

Park Rapids is surrounded by lakes and farmland, with irrigated fields of potatoes, corn, soybeans and other crops. It was forced some years ago to drill two new wells into a deeper aquifer after its water was polluted with nitrate from farm chemicals. Enbridge's water use does not threaten the city's supply, Burlingame said.

"All the irrigators up and down through this area are on the same aquifer," he said. "They use a lot more water than Enbridge is using, or the city of Park Rapids.

"We've got a lot of water."