Northshore Mining Co. operates a taconite processing plant and tailings basin in Silver Bay, which receives ore from the company's Peter Mitchell Mine. The Peter Mitchell Mine is a separate facility with its own permits.
Comment on the draft permit
The draft industrial wastewater permit for Northshore Mining's Silver Bay facility is open for public comment through May 12, 2025.
Our role
The MPCA is responsible for issuing and enforcing permits that limit air emissions and water discharge from Northshore Mining’s operations to protect the environment and health of Minnesotans. Those permits reflect current state laws and regulations.
The MPCA received an updated wastewater permit application from Northshore in April 2021 and has drafted a permit that covers the facility and its tailings basin at Mile Post 7. That permit is now available for public comment.
Project information
At Silver Bay, the coarse taconite ore is cobbed, crushed, and concentrated, then sent to the pelletizing plant, where it is formed into green pellets, fired in furnaces, stockpiled, and loaded for ship transport. Waste from the processing plant is sent to the Mile Post 7 tailings basin, about 4 miles inland from the processing plant, for disposal.
The entire facility consists of the processing plant, a steam plant, a fluoride treatment system, the Mile Post 7 tailings basin, a water treatment plant, the pipelines and rail lines between Mile Post 7 and Silver Bay, and the drainage area contributing surface runoff to the tailings basin. The processing plant draws water from Lake Superior via the former Silver Bay Power Co. steam electric generating plant, which was idled in 2019.
The draft industrial wastewater permit for the facility:
- requires water monitoring that accounts for various sources and effects of discharge, with limits to protect areas downstream
- revises the fluoride limit to align with the primary drinking water standard
- requires monitoring for dissolved mercury in accordance with the MPCA’s mercury strategy
- requires monitoring for nitrogen in accordance with the MPCA’s nutrient strategy
- updates the facility description to reflect internal operational changes
- requires groundwater and surface water monitoring in the area around the tailings basin
Next steps and timeline
The draft industrial wastewater permit is available for public comment now through May 12. A public informational meeting to discuss the draft wastewater permit will take place April 23 at 6 p.m. at the Silver Bay Reunion Hall.
After the public comment period, the MPCA will consider comments, revise the permit if necessary, and finalize it. The MPCA expects to issue a final wastewater permit for the facility in 2025.