ST. PAUL, Minn. (AP) — Minnesota regulators now say there have been more releases of drilling fluid along the Line 3 oil pipeline construction route than previously reported.

According the Minnesota Pollution Control Agency, there were 28 releases at 12 river crossing locations between June 8 and Aug. 5. In one of those cases, on July 6, about 80 gallons of fluid entered the Willow River in Aitkin County.

The MPCA also says there were 13 spills into wetlands and 14 accidental releases in upland areas, although one of those flowed into a wetland.

The agency disclosed details about the releases on Monday in a letter to Democratic state lawmakers who had requested the information, Minnesota Public Radio reported Tuesday.

Drilling fluid is used as a lubricant. It’s made mostly of bentonite clay and is not considered toxic, but can impact aquatic life.

The MPCA said Enbridge’s permit does not authorize the release of drilling fluid to wetlands or rivers. It says the releases are under investigation as potential violations.

Enbridge has said that the drilling mud was quickly contained and cleaned up under the supervision of trained environmental inspectors and independent monitors.

Line 3 construction across northern Minnesota is about 80% complete and is expected to finished in the fourth quarter.

By — Betsy Melin