Minnesota's Impaired Waters and Total Maximum Daily Loads (TMDLs)
IMPAIRED WATERS SUMMARY
(as of July 2010)
Number of water impairments (as of the 2008 inventory): 2,575 = 1,090 for conventional pollutants and 1,485 for mercury/other toxic pollutants
Number of previous impairments restored to good water quality due to implementation actions: 12 = 2 lakes and 10 river impairments
Number of active TMDLs -- either approved and in implementation, or development is underway:
- Conventional impairments: 187 TMDLs approved and 500 underway – 63% of total TMDLs needed
- Mercury impairments: 998 TMDLs approved – 77% of TMDLs needed
The federal Clean Water Act (CWA) requires states to adopt water-quality standards to protect waters from pollution. These standards define how much of a pollutant can be in the water and still allow it to meet designated uses, such as drinking water, fishing and swimming.
The standards are set on a wide range of pollutants, including bacteria, nutrients, turbidity and mercury. A water body is “impaired” if it fails to meet one or more water quality standards.
To identify and restore impaired waters, Section 303(d) of the Clean Water Act requires states to:
- Assess all waters of the state to determine if they meet water-quality standards
- List waters that do not meet standards (also known as the 303d List) and update every even-numbered year
- Conduct TMDL studies in order to set pollutant reduction goals needed to restore waters.
Federal and state regulations and programs also require implementation of restoration measures to meet TMDLs.
MPCA responsibilities include performing assessment activities, listing impaired waters, and conducting TMDLs in Minnesota. The agency also coordinates closely with other state and local agencies on restoration activities.
The Clean Water Legacy Act, passed in June 2006, allocates first-year funding to accelerate water monitoring, TMDL development and restoration activities throughout the state. The Clean Water Council was established by the Legacy Act to provide recommendations on the administration and implementation of the Act.
Links to Related Sites
- U.S. Environmental Protection Agency, Office of Water: Total Maximum Daily Load (TMDL) Program
- Minnesota Governor's Clean Water Initiative, Clean Water Cabinet
- Minnesota Department of Agriculture, Impaired Waters Program
- Minnesota Board of Soil and Water Resources
- Minnesota Department of Natural Resources
- Mississippi River Gulf of Mexico Watershed Nutrient Task Force
For More Information
- For more information on the 303(d) list of impaired waters, please contact This e-mail address is being protected from spambots. You need JavaScript enabled to view it. at the MPCA (telephone 651-757-2551 or 800-657-3864).
- For more information about TMDL planning or questions in general about the TMDL program, please contact This e-mail address is being protected from spambots. You need JavaScript enabled to view it. at the MPCA (telephone: 651-757-2670 or 800-657-3864).