Crews are digging up soil and pumps are pulling water to clean up a leak at a power plant near Cohasset in northern Minnesota. Two weeks ago Tuesday, Minnesota Power reported that wastewater containing coal ash — the waste product created when coal is burned for power — had spilled from a pipeline at Boswell Energy Center.

The company and the Minnesota Pollution Control Agency say about 5.5 million gallons of water containing ash leaked, with some of it reaching Blackwater Lake on the Mississippi River. As of Monday morning, the MPCA said about 639,000 gallons had been pumped back into the plant’s system. Sampling from the area has found higher-than-normal levels of sulfate and boron.

All this comes as the federal government is getting stricter this year with how coal ash and coal ash wastewater are regulated. Kari Lydersen has followed this as an energy reporter and investigative journalism professor with Northwestern’s Medill School of Journalism. She joined MPR News host Cathy Wurzer with context.