The designation “impaired water bodies” refers to lakes, rivers, and streams whose water quality is compromised (impaired). The Michigan Department of Natural Resources and Environment is required, under Section 303(d) of the 1972 federal Clean Water Act, to determine the health of Michigan’s waters. Waters that do not meet specific water quality standards are placed on the MDNRE’s Impaired Water Bodies List.
The Impaired Water Bodies List is an inventory of Michigan waters that require a plan for their Total Maximum Daily Load, or TMDL, of a pollutant. The TMDL is the maximum amount of a pollutant that a water body can accept without violating established water quality standards. In this context, TMDLs are important tools for achieving water quality safeguards, and for assessing the progress and impact of improvements. The methodology for developing TMDL plans varies with the type of pollutant found to be causing impairment.
The Michigan Department of Natural Resource and Environment updates the Impaired Water Bodies List every two years. You can find the most recent list here.
Impairments in Michigan
All lakes, rivers, ponds and wetlands are designated and protected for all of the following uses: agriculture; navigation; industrial water supply; warmwater fishery; other indigenous aquatic life and wildlife; partial body contact recreation (i.e. fishing, water sports); and fish consumption. In addition, they are designated and protected for total body contact recreation (i.e. swimming) from May 1 to October 1. The Great Lakes, specific Great Lakes connecting water, as well as specific rivers and inland lakes are designated and protected for coldwater fisheries. [Note: only a few segments of the Huron River are classified as coldwater.] Further, several specific segments or areas of inland waters, Great Lakes, Great Lakes bays, and connecting channels are designated and protected as public water supply sources.