In 1998, the Minnesota Pollution Control Agency (MPCA) listed the North Branch of the Sunrise River as an impaired water, under Section 303(d) of the Clean Water Act. The river, from its headwaters near Weber in Isanti County to its confluence with the main stem of the Sunrise River near Hay Creek in Chisago County, was listed as impaired for primary contact recreation and swimming. Over a period of 20 years, data have shown often excessive levels of fecal coliform bacteria loading in these waters, especially during times of increased flow due to rain or snow melt. This study assessed the current fecal coliform concentrations in the river and determined the TMDL of fecal coliform which the river could accept and still meet Minnesota water quality standards for fecal coliform. Loading capacities were allocated among point sources (wasteload allocation), nonpoint sources (load allocation) and a margin of safety. A loading capacity (i.e., TMDL) is the product of stream flow for the impaired reach and the water quality standard. Five flow zones, ranging from low flow to high flow, were utilized so that the entire range of conditions is accounted for in the TMDL. A watershed-wide reduction of approximately 52% in fecal coliform loadings would be needed to comply with Minnesota water quality standards. The strategy to bring about the necessary reductions is outlined in the implementation section of this report. The next step will be the development of an implementation plan to identify specific measures to be taken to remove the fecal coliform impairment. This plan will envision a timeline of approximately five to ten years to achieve all of the implementation practices as outlined. After this, the river will again be monitored to see if it meets the water quality standard. Once it does, the North Branch of the Sunrise River will be de-listed for fecal coliform and safe once again for swimming.
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Minnesota Pollution Control Agency (St. Paul, Minnesota)
Body of Water
Minnesota Pollution Control Agency