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Minnesota's Impaired Waters and TMDLs

Impaired Waters

Section 303(d) of the Clean Water Act requires states to publish and update a list of waters that are not meeting one or more water-quality standards. The list, known as the 303(d) Total Maximum Daily Load (TMDL) list, is updated every two years (the next list will be approved in 2010). Following assessment of water quality data and an extensive public participation process, the draft TMDL list is submitted to the U.S. EPA for final approval.

As noted above, the 2010 draft TMDL List contains 1,774 impairments. This is the list for which TMDL pollution reduction studies are required. But this is not the complete list of all impaired waters. The Inventory of impaired waters includes those needing a TMDL plan as noted above and those for which plans has already been developed and approved by US EPA. The Inventory also includes waterbodies that are naturally impaired, such as the arsenic exceedances in the Red River of the North.

While the draft 2010 TMDL List has 1,774 impairments, the Inventory of all impaired waters contains 3,049 impairments. Waters in the Inventory of impaired waters will remain there until they meet water quality standards.

2010 Draft TMDL List

•  Draft List of Waters Needing TMDLs (303d List of Impaired Waters)
• Inventory of all Impaired Waters - a complete list of all 3,049 impairments
• Introductory Cover Page to List
• Guidance Manual for Assessing the Quality of Minnesota Surface Waters for Determination of Impairment: 305(b) Report and 303(d) List
• Revisions to Appendix of the Mercury TMDL

     Draft 2010 TMDL List (1,774 total)

Impaired Waters Maps

Statewide

• Bioaccumulative toxics
• Eutrophic Lakes and Impaired Wetlands
• Rivers, Conventional Parameter Impairments

Statewide

• Lakes: Aquatic recreation use
• Streams: Aquatic recreation use
• Streams: Aquatic life use

Basin

• Lake Superior Basin
• Lower Mississippi River and Cedar River Basins
• Metropolitan Area
• Minnesota River Basin
• Rainy River Basin
• Red River Basin
• St. Croix Basin
• Upper Mississippi River Basin

Meetings and Events

The MPCA held seven public information meetings. The following presentation was given at each meeting.

• The 2010 draft TMDL list of impaired waters

TMDL List Archives

•  2008
•  2006
•  2004
•  2002
•  1998