What is a TMDL (Total Maximum Daily Load) Study?
MPCA: The federal Clean Water Act of 1972 requires the appropriate state agency, in our case the MPCA, to report to the federal Environmental Protection Agency (EPA) a list of all water bodies and streams that have been assessed as impaired (that is, they do not meet standards for their designated use) during a formal listing process. This happens every two years. Then the state is required to conduct a TMDL study for each pollutant that causes a water body to fail to meet its designated use and the associated state water quality standards. The TMDL study is a written plan that analyzes the causes of the problem and determines how water quality standards will be attained. A TMDL study identifies both point and non-point sources of each pollutant that fails to meet water quality standards. Lakes, rivers and streams may have several TMDLs, one for each pollutant. A good example of an approved TMDL study, for Lake Independence in Wright County, can be found at: http://www.pca.state.mn.us/
