Amendments to Water Quality Standards: Use classifications 3 and 4

In this rulemaking, the MPCA proposes to amend the existing rules governing water quality standards for industrial consumption (Class 3) and agricultural (Class 4A) and livestock and wildlife usage (Class 4B). Please note that this rulemaking will not address the Class 4A wild rice sulfate standard.

Summary of planned changes

  • Update the Class 3 water quality standard to
    • Remove the multiple subclasses of the use;
    • Remove the numeric standards;
    • Retain and revise the narrative standard;
    • Provide clarity around implementation of the narrative standards in discharge permits, including a robust implementation approach that is based on specific site conditions and focuses on water hardness;
  • Update the Class 4A irrigation water quality standards to:
    • Remove several of the numeric standards;
    • Retain and revise the narrative standard; 
    • Provide clarity around implementation of the narrative standards in discharge permits, including a robust implementation approach to protect crops from salts that is based on specific water, soil, and crop conditions;
  • Update the numeric standards for Class 4B to reflect current science and improve clarity;
  • Generally clarify the standards and uses of wetlands, so that the standards are clearly linked to the appropriate designated uses;

Learn more

Revised Class 3 & 4 Waters Rulemaking Schedule

The Minnesota Pollution Control Agency (MPCA) has released a revised timeline for proposed changes to existing rules governing water quality standards for industrial consumption (Class 3) and agricultural and wildlife usage (Class 4). The MPCA has received significant public feedback during the Class 3 & 4 waters rulemaking process and is preparing final rule language. The MPCA expects its rulemaking to be completed in mid- 2021.

Mid-October 2020

Recognizing and supporting the unique status of Minnesota Tribal Nations, the MPCA will meet with Tribal Nations to solicit feedback that may be considered prior to releasing the draft rule language. 

Late October 2020

To give the public more time to review the proposed rule language, the MPCA will post its draft rule on the agency’s website during the week of October 29. The agency will not be soliciting comments on the draft until the formal notice period. The MPCA previously asked for public feedback during two comment periods in 2016 and 2019.

Late November 2020

The proposed rule language, along with Statement of Need and Reasonableness (SONAR), will be published with a notice of intent to adopt the rule. The notice will also include a schedule for an administrative law judge hearing. The public may provide comments prior to the hearing.

January 2021

The Office of Administrative Hearings will conduct an administrative law judge hearing. The public will have an opportunity to provide comments during this hearing and in a post-hearing comment period of a length set by the judge. 

March 2021 – August 2021

The Office of Administrative Hearings report regarding the proposed rule changes is due 30 days after the close of the post-hearing comment period. The report may lead to needed changes to the rule. If the rule is approved, MPCA will go through the process to formally adopt the rule and submit it to U.S. EPA for approval.

Rulemaking and technical support documents

2020 Preliminary Draft Rule Language

  • Expected in late-October 2020. Comments will not be taken until the rule language and SONAR are made available as part of a formal Notice of Intent to Adopt Rules with a Hearing.

2019 Request for comments (March 11 - April 22, 2019)

2016 Request for comments (February 8 – April 8, 2016)

2010 Evaluation from the University of Minnesota’s Department of Bioproducts and Biosystems Engineering

Contact information

For technical questions about these use classifications and the proposed changes:
Scott Kyser: scott.kyser@state.mn.us, 651-757-2665

You can register at GovDelivery to be notified when draft rule language is published.