As required by the federal Clean Water Act, the MPCA assesses all waters of the state and creates a list of impaired waters — those that fail to meet water quality standards — every two years. The listings are based on intensive water monitoring of major lakes and streams 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.
Approved by U.S. EPA on April 29, 2022, this list includes: 2022 TMDL list (303(d)); 2022 Inventory of all impaired waters; Delisted waters; Appendix A of the Statewide Mercury TMDL
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 water before it is no longer drinkable, swimmable, fishable, or useable in other, designated ways (called “beneficial uses”).
Impairments include:
- Mercury levels that lead to limits on fish consumption
- Phosphorus and other 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 impairments that may hinder the production of wild rice
Public engagement
The MPCA responded to all written comments received through Jan. 7, 2022. EPA took all public comments and MPCA responses into consideration when approving of Minnesota’s Impaired Waters List on April 29, 2022.