Turbidity TMDL Assessment for the Pomme de Terre River Final Report

The Minnesota Pollution Control Agency (MPCA) listed one stream reach on the Pomme de Terre River, from Muddy Creek to Marsh Lake (HUC: 07020002-501), as impaired for the designated use of supporting aquatic life under Section 303(d) of the Clean Water Act. The pollutant of concern contributing to the impairment is excessive turbidity. This Total Maximum Daily Load (TMDL) report describes the magnitude of the problem and provides direction for improving water quality for the listed reach. The turbidity impairment seems to be directly correlated with rainfall events during the months of June, July and August. While the highest flows in the river occur in April due to the snowmelt runoff, the highest turbidity and TSS readings occur in June, which is the month with the highest average precipitation. Using the duration curve approach, and noting the hydrologic conditions where most of the exceedances occur, it shows that the increased load may be the result of sediment delivery associated with rainfall and runoff from riparian areas and saturated soils in the upland areas under wetter conditions.