Understanding Impairments and TMDLs

The 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.

Impaired waters are those waters that don't meet water quality standards for one or more pollutants.

Impaired Waters Research Symposium Feb 2008

Read about the TMDL efforts underway for:

• Miller Creek
• Knife River (exit)
• Poplar River
• Minnesota Impaired Waters and TMDLs (exit)

Maps showing the impaired streams in the Minnesota Lake Superior Basin:

• Conventional parameters (including excessive nutrients, fecal coliforms, turbidity, temperature, biotic indices, low dissolved oxygen, and chloride)
• Bioaccumulative toxins (including mercury, pesticides and PCBs)

National Info:

The Assessment Total Maximum Daily Load (TMDL) Tracking and Implementation System (ATTAINS) provides information reported by the states to the USEPA about the conditions in their surface waters.