Phase II Addendum Project Report to the MPCA: Clearwater River, Grass Lake to the Mississippi River DO TMDL

Section 303(d) of the Federal Clean Water Act (CWA) requires the Minnesota Pollution Control Agency (MPCA) to identify water bodies that do not meet water quality standards and to develop total maximum daily pollutant loads for those water bodies. A total maximum daily load (TMDL) is the amount of a pollutant that a water body can assimilate without exceeding the established water quality standard for that pollutant. Through a TMDL, pollutant loads can be distributed or allocated to point and non-point sources within the watershed that discharge to the water body. This report prepared by Wenck Associates, Inc. (Wenck) on behalf of the Clearwater River Watershed District (CRWD), presents Phase I and II of the TMDL process for the listed segment of the Clearwater River between Grass Lake and the Mississippi River (Segment 07010203-511). The listed segment is in the CRWD located in central Minnesota on the border of Stearns and Wright Counties. The segment is listed because monitoring data have revealed that dissolved oxygen (DO) concentrations at times fall below the 5-milligram per liter (mg/L) water quality standard, which could impact fisheries and aquatic life.