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As required by the federal Clean Water Act, the MPCA assesses all waters of the state and updates the list of impaired waters every two years. This list includes waters that fail to meet water quality standards and uphold that water body’s designated use.

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Your dollars at work

Funding for this initiative comes from the Clean Water Fund, part of the Clean Water, Land and Legacy Amendment that Minnesotans approved in 2008. The MPCA uses Clean Water Fund dollars to protect, enhance, and restore water quality in lakes, rivers, streams, and groundwater.

The listings are based on intensive water quality monitoring of major lakes and streams in Minnesota’s 80 watersheds, along with data from partners. This list is used to set pollutant-reduction goals needed to restore impaired waters, called the total maximum daily load (TMDL).

6896: Proposed 2026 Impaired Waters List docs

Draft 2026 Impaired Waters List

The 2026 list was submitted to EPA for final approval on Sept. 28, 2026. Delistings and additions to the list are not final until EPA approval.

The draft list includes the 2026 inventory of all impaired waters; 2026 total maximum daily load (TMDL) list (303(d) list); Appendix A of the Statewide mercury TMDL; delisted waters; changes and corrections from the 2024 list.

The guidance manual describes Minnesota's monitoring and assessment strategy, assessment tools, and the assessment process. The purpose of this guidance is to define the required data and information. It also lays out the criteria by which waterbodies are assessed to determine if beneficial uses are supported or impaired. It also contains changes to Appendix H regarding identification of wild rice waters.

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Defining impaired waters

A body of water is considered “impaired” if it fails to meet one or more water quality standards. Minnesota water quality standards protect lakes, rivers, streams, and wetlands by defining how much of a pollutant can be in the water before it is no longer drinkable, swimmable, fishable, or useable in other, designated ways (called “beneficial uses” or “designated uses”). A water impaired for one beneficial use does not mean it cannot be used for other beneficial uses.

Impairments include:

  • mercury levels that lead to limits on fish consumption
  • nutrients that grow algae
  • sediment that clouds water
  • bacteria that can make water unsafe for swimming
  • unhealthy conditions for fish and bugs
  • PFOS found in fish tissue
  • sulfate levels that may hinder the biological production of wild rice

The MPCA works with many partners to identify the sources of pollutants and stressors to aquatic life, and determine reductions in pollutants and other changes needed to restore waters to meet water quality standards.

Other information

MPCA uses this biennial narrative report to meet some of the reporting requirements under the federal Clean Water Act.

Minnesota’s 2024 Impaired Waters List: