Total Maximum Daily Load for Nitrate and E.Coli, Raccoon River Iowa, 2008

(2008) Total Maximum Daily Load for Nitrate and E.Coli, Raccoon River Iowa, 2008. Natural Resources, Department of

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Abstract

The Federal Clean Water Act requires the Iowa Department of Natural Resources (IDNR) to develop a Watershed Improvement Plan, also known as a Total Maximum Daily Load (TMDL), for waters that have been identified on the state’s 303(d) list as impaired by a pollutant. Three segments of the Raccoon River have been identified as impaired by nitrate-nitrogen (nitrate) and five segments have been identified as impaired by the pathogen indicator Escherichia coli (E.coli) bacteria. TMDLs have been determined for the eight segments. The purpose of these TMDLs is to calculate the maximum allowable nitrate and pathogen loads for the impaired segments of the Raccoon River that will allow the river to meet water quality standards. TMDLs for pathogen indicator E.coli have also been determined for all other Class A1 streams in the Raccoon River watershed not previously identified as impaired. Although these segments have not been listed on the state’s 303(d) list, TMDLs have been determined for these segments in the event that monitoring data is collected in the future that could be used for listing purposes.