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Developed though the 2020-2021 triennial standards review, the MPCA’s work plan for 2021 to 2023 includes projects currently in the rulemaking process and others that are in development and not yet ready for rulemaking. See the written description of the work plan for more detail about each project and expected development timelines.

Group 1A projects

Group 1A projects are in rulemaking and have an estimated timeline for adoption into state law. In this stage, the MPCA is responding to changes needed due to peer review (when applicable), finalizing the technical support document, and developing the Statement of Need and Reasonableness (SONAR) and final rule language. The need for peer review will affect the rulemaking timeline.

Use Classes 2A (cold waters) and 2B (cool and warm waters)

Revisions to Class 2A and 2B waters are needed to update and align these designations with the improved tools now used by MPCA to assess the condition of Minnesota’s waters, including the indices of biotic integrity and other biological criteria. This is the second set of revisions related to implementation of the Tiered Aquatic Life Use (TALU) framework, which added new Class 2 beneficial use tiers for aquatic life. A request for comment was published in the State Register on April 5, 2021, and closed on May 7, 2021. The proposed rules are scheduled to be published in December 2021. 

Group 1B projects

For Group 1B projects, the agency has a basic concept of what may be included in the rule language and is preparing supporting documentation. Draft technical support documents for new or revised numeric standards go through an initial public comment period and independent peer review if required. When the technical support document is sufficiently complete, generally in two to three years, these pre-rulemaking projects will move into Group 1A and formal rulemaking.  

Use Class 1 (drinking water)

Minn. R. ch. 7050 addresses drinking water use through the Class 1 Domestic Consumption designation, which applies to all groundwater and some surface waters. MPCA designates Class 1 waters and applies water quality standards (WQS) following Minn. R. ch. 7050.0221; listings of Class 1 surface waters are in Minn. R. 7050.0470.  These rules predate the Safe Drinking Water Act (SDWA) (added to the Clean Water Act in 1974) as well as State Statute 103H, also known as the 1989 Groundwater Protection Act. Revisions to the Class 1 rules are needed to better define and protect waters used for domestic consumption (drinking water use and food processing), and address the inconsistencies and gaps in Minn. R. chs. 7050 and 7060 (underground waters). In addition, MPCA is considering: 

  • updating numeric and narrative Class 1 WQS.
  • adding language to address surface water and groundwater interaction.
  • adding Groundwater Contaminant Management Zones (GCMZs) to Minn. R. ch. 7060, to inform the public, state and local regulators, and others about areas of groundwater contamination.

Development of the revisions is underway, in consultation with the Minnesota Department of Health (MDH) and other state agency partners with related authorities. MPCA plans to publish a request for comment providing more details about the revisions under consideration in November 2021, and ask for the public’s input on these potential changes prior to moving forward with rule development. 

Revisions to lake eutrophication WQS

This revision potentially includes several elements needed to update and modernize the eutrophication WQS for lakes.  They include: 1) revising the northern lake eutrophication standards by adding standards for a shallow lake type, 2) reviewing protections for cold water fish species including lake trout, lake whitefish, and cisco and developing standards where needed, 3) review and designation of cold water lakes, 4) adoption of a TALU framework for lakes, and 5) minor corrections and housekeeping revisions. A request for comment is expected to be published for this rulemaking before the end of 2021.


Nitrogen is a key pollutant in Minnesota’s water and has impacts both locally and downstream. Development of a Class 2 aquatic life water quality standard for nitrate is a long-time identified need. The MPCA, in coordination with our partners, is proposing a holistic, step-wise approach to help reduce nitrogen levels statewide prior to adopting a new nitrate aquatic life toxicity water quality standard. These include developing a wastewater nitrogen reduction strategy with targeted action to reduce nitrogen and completing the 10-year revision of the nutrient reduction strategy.

Ammonia – aquatic life

Revision of the ammonia water quality standard to protect aquatic life has been a priority since 2013, when EPA issued a revised criteria for this pollutant. We are moving ahead with this revision.

Group 2A projects

Group 2A projects are in technical development and have all the information needed from outside the MPCA to evaluate how the standard will address environmental or programmatic concerns, and to assess the resources needed to promulgate and implement the standard. Before  advancing the project into Group 1, the agency must determine if it is  able to accommodate the added work of implementing a new WQS in addition to its regular permitting and related work. Group 2A projects are likely to move into Group 1B within one to two years.

Aluminum, copper and cadmium WQS – aquatic life

EPA developed updated criteria for aluminum, copper and cadmium that reflect the latest scientific knowledge regarding the toxicity of these pollutants to aquatic life. The new criteria for aluminum and cadmium incorporate water hardness into the standard; the new criteria for copper is based on the biotic ligand model, which considers the amount of pollutant that is bioavailable and impacts aquatic life.    

These revisions are needed to maintain the currency of Minnesota’s water quality standards.

Group 2B projects

Group 2B projects are in initial technical development, which typically involves many tasks such as reviewing scientific literature, reviewing Minnesota-specific data, designing and undertaking studies, and (if available),reviewing and refining an EPA criteria document. Group 2B projects lack needed information to complete technical development and move to Group 2A. Because the information needs and technical approaches for developing WQS vary widely, it is difficult to estimate the time needed to advance these projects.

Chloride – aquatic life

The Class 2 aquatic life standard for chloride was selected for review and revision in previous triennial standard reviews because newer science suggested Minnesota’s WQS was potentially outdated. Since then, scientific studies have demonstrated that the interactions of ions (e.g., chloride, sulfate, calcium, and others) must be considered to accurately account for chloride’s toxicity. EPA is currently developing criteria for chloride along with sulfate and potentially other ions, and expects to issue draft criteria in 2022. MPCA is tracking EPA’s work on ions and expects EPA’s broad consideration of ionic toxicity will result in better and more comprehensive protection for aquatic life compared to more narrowly defined approaches in common use by states now.    

Sulfate – aquatic life

Adding a Class 2 aquatic life standard for sulfate was selected in the last triennial standard review to add general aquatic life protection for sulfate to Minnesota’s WQS. As described above for chloride, scientific studies have demonstrated that the interactions of ions (e.g., chloride, sulfate, calcium, and others) must be considered to accurately account for sulfate’s toxicity. EPA is currently developing criteria for sulfate along with chloride and potentially other ions, and expects to issue draft criteria in 2022. MPCA is tracking EPA’s work on ions and expects EPA’s broad consideration of ionic toxicity will result in better and more comprehensive protection for aquatic life from sulfate compared to development of a WQS for sulfate alone.        

Group 3 projects

The MPCA has not started developing Group 3 projects because of missing technical information, a lack of capacity, or both. Group 3 projects are likely to proceed to standard development, but they may remain in Group 3 without significant progress towards regulatory development throughout the three year triennial period.

Revisions to river total suspended solids (TSS) WQS – aquatic life

This revision may be needed to account for rivers that have naturally high TSS and also high quality biological communities (e.g., rivers in glacial lake beds where the soil can have high silt and clay content). A thorough review of Minnesota’s TSS and biological monitoring data (fish and invertebrates) must be completed prior to moving forward with this project, to ascertain the basis and likely approach for the revision. This review will be accomplished as staff availability allows.

HH-WQS for PFOS in fish tissue

Development of a statewide, fish-tissue based HH-WQS for perfluorooctanesulfonic acid (PFOS) is needed to address the large number of Minnesota waters that are impaired for PFOS in fish tissue. PFOS is an industrial pollutant that builds up (bioaccumulates) in fish and other aquatic life; Minnesota has been monitoring the presence of PFOS in fish tissue for several years.  

The PFAS Blueprint (Feb. 2021) identified development of this WQS as a longer term (more than two years out) need; a key reason is that effective, feasible methods to manage PFAS-contaminated water, biosolids, and other media are not yet available and are needed to broadly implement a WQS. MPCA developed a site-specific criteria (SSC) for PFOS in fish tissue for Lake Elmo and connected waterbodies, Bde Maka Ska and Pool 2 of the Mississippi River that was updated in 2020 and is available as a reference point; however, a WQS that applies statewide, as this WQS topic will, requires additional development and is required to go through formal peer review prior to entering rulemaking.

Imidacloprid and Clothianidin – aquatic life

The Minnesota Department of Agriculture (MDA) recently named clothianidin and imidacloprid as pesticides of concern in surface water. This designation means these pesticides were detected at concentrations of concern to aquatic life in rivers and streams relative to a water quality reference value. Minnesota does not have WQS for these pesticides.

Group 4 projects

Group 4 projects do not have a priority status with regard to development but are important water quality standards work. They include review of outstanding resource value waters and review of Class 7 waters, both of which are conducted on an as-needed basis, such as when new information becomes available about a water body.