MPCA water quality permits establish specific limits and requirements to protect Minnesota's surface and groundwater quality for a variety of uses, including drinking water, aquatic life and recreation. These are also known as NPDES/SDS permits (National Pollutant Discharge Elimination System/State Disposal System).
The MPCA typically follows the process below for processing individual water quality permit applications.
* includes coordination with EPA
The public comment period for the draft water quality permit for PolyMet’s NorthMet project closed on March 16, 2018. The MPCA reviewed all comments and information received and has finalized responses to comments. This process resulted in changes to the draft permit that the MPCA incorporated into the proposed permit. The proposed permit and supporting documents were sent to the Environmental Protection Agency (EPA) for 15-day review on December 4, 2018 as part of the regular federal oversight of the state permitting program. Following conclusion of the review period, MPCA issued the final water quality permit on December 20, 2018.
Previous supporting documents
Public notice draft permit, fact sheet, and fact sheet attachments
Public meeting fact sheets
PolyMet permit highlights (wq-wwprm1-51t) (Jan 2018)
NPDES/SDS permit and sulfate (wq-wwprm1-51u) (Jan 2018)
Reverse osmosis (wq-wwprm1-51v) (Jan 2018)
October 2017 updated NPDES/SDS permit application
NPDES/SDS Permit Application - Vol II: Mine site (wq-wwprm1-50v) (pdf 145.3 mb) (Oct 2017)
The initial July 2016 permit application and November 2016 update:
Key references cited in application
Wastewater Treatment System: Design and Operation Report v2 (wq-wwprm1-51b) (108.9 mb) (Oct 2017)
Correspondence related to permit application
Construction stormwater permit for Polymet
On November 24, 2020, the MPCA approved the Stormwater Pollution Prevention Plan (SWPPP) and issued coverage under the Construction Stormwater General Permit for the transportation and utility corridor. This permit, along with other previously issued construction stormwater permits, authorizes land-disturbing construction activities to begin. Some examples include removing vegetation, like grass or trees, or changing topography using a bulldozer to level a slope.
The MPCA has issued Construction Stormwater General Permits for the tailings basin, plant site, mine site, and transportation and utility corridor. Ongoing legal proceedings regarding the MPCA-issued NPDES and air permits, as well as DNR-issued permits, have resulted in a temporary stay. The proposed Polymet facility cannot operate until the courts lift the stay and resolve any ongoing legal matters.
Information regarding the Construction Stormwater General Permits for the tailings basin, plant site, mine site, and transportation and utility corridor is available online in the Construction Stormwater Permit Search.
Stormwater Pollution Prevention Plans (SWPPP)
To obtain a Construction Stormwater general permit, Polymet or its contractors must develop a Stormwater Pollution Prevention Plan (SWPPP), specific to the project, which details how the requirements of the permit will be met. The SWPPP identifies the practices that will be implemented at the project to protect the environment and meet the requirements of the general permit. The SWPPP becomes an enforceable part of the permit.
- SWPPPs reflect the project at the time of application and are considered living documents.
- SWPPPs are required to be amended if site conditions change in order to meet permit requirements throughout the life of the project and control stormwater discharges from the site.
- Common best management practices on these types of sites are perimeter controls including silt fence or sediment logs, temporary and permanent stabilization with seed and mulch. These practices are required to keep sediment on site and prevent sediment laden discharges to waters of the state.
The Polymet SWPPP is found here.
Construction stormwater general permit
When a project includes land-disturbing activities totaling an acre or more, a Construction Stormwater general permit must be obtained from the Minnesota Pollution Control Agency. Land-disturbing activities are regulated by this permit because they have the potential to allow stormwater—runoff caused by rain and snowmelt—to carry dirt and pollutants into our lakes, rivers and streams. The Construction Stormwater general permit requires the installation and maintenance of management practices to reduce potential pollution.
When an applicant seeks coverage under this permit, there is no additional public comment period. When an applicant has submitted a complete and accurate application in accordance with the requirements of the permit, they can be authorized to discharge stormwater associated with construction activity under the permit.