Snake-Middle Rivers Watershed Total Maximum Daily Load Report

This Total Maximum Daily Load (TMDL) report was completed for impaired waterbodies of the Snake Middle Rivers Watershed (Hydrologic Unit Code [HUC] 09020309), which enters the Red River of the
North west of Argyle, Minnesota, and is part of the Lake Winnipeg Basin (HUC-09). There are a total of 32 aquatic life use, aquatic recreation use, and aquatic consumption use impairments (3 caused by Escherichia coli [E. coli], 5 caused by turbidity, 7 caused by low dissolved oxygen [DO], 16 caused by poor biological communities, and 1 caused by mercury in the water column) included on Minnesota’s U.S. Environmental Protection Agency (EPA)-approved 2018 303(d) list of impaired waters for the Snake-Middle Rivers Watershed. TMDLs were completed for this report to address 8 of the 31 aforementioned impairments. The TMDLs include three river/stream-reach aquatic recreation use impairments caused by E. coli and five river/stream-reach aquatic life use impairments caused by turbidity. The goal of these TMDLs is to quantify the pollutant reductions needed to meet the state water quality standards for E. coli and total suspended solids (TSS) for impaired streams. TMDLs were not completed for 24 of the 32 impairments. No impairments caused by poor fish or macroinvertebrate communities (n= 9 and 7, respectively) were addressed, because while all of them are linked to stressors with numeric criteria to some extent, the impairments are primarily linked to stressors without numeric criteria (e.g., flow regime instability and poor habitat) that cannot have TMDLs calculated. The seven DO impairments were not addressed for various reasons ranging from lack of information to lack of reasonable assurance that the reductions required to meet a TMDL could be met. This report does not cover toxic pollutants so the aquatic consumption use impairment caused by mercury in the water column is not addressed. Mercury concentrations are above the threshold values for this impairment to be addressed by the Minnesota Statewide Mercury TMDL, so it is scheduled to have a TMDL study completed at a later date. No other TMDLs have previously been developed for waters in the Snake-Middle Rivers Watershed