PolyMet’s NorthMet mining project

MPCA issues PolyMet final air and water quality permits and 401 certification

On December 20, 2018, the MPCA made final regulatory decisions to issue the PolyMet air emission permit, water quality permit, and 401 certification.  The decisions were reached after comprehensive regulatory and technical analysis, extensive public participation, and review by other state/federal agencies and independent third-party experts.

This notification is the MPCA’s final progress report on the status of the PolyMet air emission permit, water quality permit, and 401 certification.

Aerial view of proposed mining project area

Poly Met Mining, Inc. (PolyMet) is proposing to develop a mine and processing plant to extract copper, nickel, and precious metals from the NorthMet Deposit in northeastern Minnesota.

The NorthMet project is located about six miles south of Babbitt and one mile south of the existing Northshore (iron ore) Mine. Processing of the ore would take place at the former LTV taconite plant near Hoyt Lakes.

The total project includes a new open pit mine, temporary and permanent waste rock disposal areas, recommissioning of an existing processing plant and tailings basin, and refurbishment of an existing seven-mile railroad and utilities corridor between the mine and plant sites.

Environmental Review

The Minnesota Department of Natural Resources, US Forest Service, and US Army Corps of Engineers conducted a comprehensive environmental review of the proposed project.


The MPCA's role is to protect water and air, which it does, in part, through the issuance of environmental permits.

When any facility submits an application to MPCA to obtain a permit, technical staff review the application and evaluate whether the facility can meet applicable environmental regulations and standards. The MPCA then develops facility-specific permit conditions. Permit conditions ensure that all standards are met by specifying how the facility must be operated, describing monitoring that must be conducted, and limiting the type and amount of water discharges or air emissions.

The individual air quality and NPDES/SDS wastewater permits for the NorthMet project, and Section 401 (Clean Water Act) certification are effective Dec. 20, 2018.

For more information about permits, see the following:

The MPCA follows the general process below for processing permits and certification:

MPCA permitting process

* includes coordination with EPA