Water quality permit for NorthMet

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.

Water permit process with marker showing current status as completeness review

* includes coordination with EPA

Current status

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.

PDF icon FINAL PolyMet NPDES-SDS Permit (wq-wwprm1-51ff)

PDF icon FINAL PolyMet NPDES-SDS Permit Fact Sheet (wq-wwprm1-51gg)

PDF icon FINAL PolyMet NPDES-SDS Response to Comments (CCH and Indiv)(wq-wwprm1-51oo)

PDF icon FINAL PolyMet NPDES-SDS Findings of Fact (wq-wwprm1-51pp)

Previous supporting documents

Public notice draft permit, fact sheet, and fact sheet attachments

PDF icon Draft NPDES/SDS Permit (wq-wwprm1-51j)

PDF icon Draft NPDES/SDS Permit Fact Sheet (wq-wwprm1-51k)

PDF icon Draft NPDES/SDS Permit Fact Sheet, Attachment 1 (wq-wwprm1-51l)

PDF icon Draft NPDES/SDS Permit Fact Sheet, Attachment 2 (wq-wwprm1-51m)

PDF icon Draft NPDES/SDS Permit Fact Sheet, Attachment 3 (wq-wwprm1-51n)

PDF icon Draft NPDES/SDS Permit Fact Sheet, Attachment 4 (wq-wwprm1-51p)

PDF icon Draft NPDES/SDS Permit Fact Sheet, Attachment 5 (wq-wwprm1-51q)

Public meeting fact sheets

PDF icon NPDES permit and PolyMet requirements (wq-wwprm1-51s) (Jan 2018)

PDF icon PolyMet permit highlights (wq-wwprm1-51t) (Jan 2018)

PDF icon NPDES/SDS permit and sulfate (wq-wwprm1-51u) (Jan 2018)

PDF icon Reverse osmosis (wq-wwprm1-51v) (Jan 2018)

October 2017 updated NPDES/SDS permit application

PDF icon NPDES/SDS Permit Application - Vol I: Introduction (wq-wwprm1-50u) (Oct 2017)

PDF icon NPDES/SDS Permit Application - Vol II: Mine site (wq-wwprm1-50v) (pdf 145.3 mb) (Oct 2017)

PDF icon NPDES/SDS Permit Application - Vol III: Waste Water Treatment System (wq-wwprm1-50w) (Oct 2017)

PDF icon NPDES/SDS Permit Application - Vol IV: Plant Site Sewage Treatment and Stormwater (wq-wwprm1-50x) (Oct 2017)

PDF icon NPDES/SDS Permit Application - Vol V: Tailings Basin and Beneficiation Plant (wq-wwprm1-50y) (Oct 2017)

PDF icon NPDES/SDS Permit Application - Vol VI: HRF and Hydrometallurgical Plant (wq-wwprm1-50z) (Oct 2017)

PDF icon NPDES/SDS Permit Application - Vol VII, Transportation and Utility Corridors (wq-wwprm1-51a) (Oct 2017)

The initial July 2016 permit application and November 2016 update:

PDF icon NPDES-SDS Permit App - Vol I – Introduction v1 JUL2016.pdf

PDF icon NPDES-SDS Permit App - Vol II - Mine Site v1 JUL2016.pdf

PDF icon NPDES-SDS Permit App - Vol III - Waste Water Treatment System v1 JUL2016.pdf

PDF icon NPDES-SDS Permit App Vol IV-Plant Site Sewage Treatment and Stormwater v1 JUL2016.pdf

PDF icon NPDES-SDS Permit App - Vol V – Tailings Basin and Beneficiation Plant v1 JUL2016.pdf

PDF icon NPDES-SDS Permit App Vol VI–HRF and Hydrometallurgical Plant v1 JUL2016.pdf

PDF icon NPDES-SDS Permit App Vol VII - Transportation and Utility Corridors v1 JUl2016.pdf

PDF icon NorthMet Project NPDES/SDS Permit: Application Update Nov. 30, 2016 (wq-wwprm1-50r)

Key references cited in application

PDF icon Wastewater Treatment System: Design and Operation Report v2 (wq-wwprm1-51b) (108.9 mb) (Oct 2017)

PDF icon Water Management Plan - Plant (wq-wwprm1-50a) updated July 2016

PDF icon Flotation Tailings Management Plan (wq-wwprm1-50b)

PDF icon Geotechnical Data Package Vol 2.pdf

PDF icon Adaptive Water Management Plan.pdf

PDF icon Installation and Monitoring Plan for Wells N of Mine Site.pdf

PDF icon Mercury Overview.pdf

PDF icon Mine Plan.pdf

PDF icon NorthMet Project Description.pdf

PDF icon Plant Site Wastewater Treatment Plant Pilot testing.pdf

PDF icon Reclamation Plan.pdf

PDF icon Residue Management Plan.pdf

PDF icon Surface water and groundwater quality data collected 2014 2015.pdf

PDF icon Waste Water Treatment System Design and Operation Report.pdf

PDF icon Water Management Plan - Mine (wq-wwprm1-50p) updated July 2016)

PDF icon Wetland Residence Time.pdf

Correspondence related to permit application

PDF icon MPCA Application Completeness letter (Aug. 2, 2016)

PDF icon PolyMet response to EPA letter (Nov. 9, 2016)

PDF icon November 9, 2016 Comment Letter Response

Construction stormwater permit for Polymet

Current status

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.

More on water permitting