Minnesota Power ups wastewater spill estimate to 5.5M gallons

COHASSET — The size of a coal ash wastewater leak at Boswell Energy Center in Cohasset is now estimated to be five times larger than initial reports.

Minnesota Power updated its estimate Friday, July 19, to 5.5 million gallons leaked at its coal power plant situated near lakes and rivers. The company first reported an estimated 1 million gallons spilled Tuesday morning into soils, Blackwater Creek and Blackwater Lake.

A pipe that transfers wastewater from a pond to the power plant is believed to be the likely source of the leak. Minnesota Power reported a loss of pump pressure caused the leak, the Minnesota Pollution Control Agency said in a statement Wednesday.

Initial test results show sulfate levels below the drinking water standard but above Minnesota’s wild rice-based standard, the MPCA reported Friday. Preliminary monitoring and sampling also indicate increased levels of boron where the wastewater entered Blackwater Creek.

MPCA said it hired an environmental contractor to conduct independent monitoring and sampling.

Mitigation activities are expected to increase over the weekend, the statement read, and Minnesota Power plans to excavate affected soil to remove contaminants. The area is being assessed for cultural and tribal resources before excavation with the Leech Lake Band of Ojibwe.

Bay West, Minnesota Power’s environmental contractor, set up deep-skirted booms and staked a silt curtain to Blackwater’s lakebed Thursday.

Leech Lake Emergency Management Director Duane Oothoudt has been harvesting wild rice on Blackwater Lake for nearly a decade. In an interview Thursday, he expressed concern about how the spill will impact an important cultural resource.

“People rice here, and they eat the rice,” Oothoudt said. “ ... This impacts a lot of the local harvesters and foragers and our land rights. It’s pretty close to the reservation border, so it does impact us.”

MPCA said it is focused on "evaluating concentrations and extent of potential pollutants” and the impact on soils, Blackwater Creek and Lake, aquatic life and wild rice beds.

Funding for this environmental story was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR).