Final Lake of the Woods Watershed Total Maximum Daily Load Study

The greater Lake of the Woods Watershed (LOWW) falls on the U.S. and Canadian border. This study will focus on the Minnesota portion of the LOWW (Hydrologic Unit Code [HUC] 09030009) draining 734,783 acres in the northernmost Minnesota counties of Lake of the Woods and Roseau. The LOWW’s namesake, the Lake of the Woods, takes up approximately 42% of the total LOWW area in Minnesota, with approximately 70% of the remaining watershed area in wetlands and another 20% of land use in
agriculture, found mainly along the southern lake shore of the Lake of the Woods (MPCA 2016a). The 2018 federal Impaired Waters 303(d) list identifies seven LOWW streams as having impaired water quality (i.e., not meeting water quality standards) and requiring TMDL studies. These streams contain a total of 15 impairment listings: 3 for impaired aquatic life caused by low dissolved oxygen (DO) levels, 1 for impaired aquatic recreation caused by high Escherichia coli (E. coli) levels, 4 for impaired aquatic life determined by fish bioassessments (F-IBI), 5 for impaired aquatic life determined by macroinvertebrate bioassessments (M-IBI), and 2 for impaired aquatic life due to high total suspended solids (TSS) levels. The 3 TMDLs completed in this study address 6 of the 15 impairments, the 2 TSS impairments and 4 of the bioassessment-related impairments where TSS was identified as a contributing stressor. Due to insufficient data, the E. coli and DO impairments are expected to be addressed in a future TMDL study. he findings in this TMDL study were used to guide the development of implementation strategies as part of the Lake of the Woods Watershed Restoration and Protection Strategies (WRAPS) process. The purpose of the WRAPS report is to support local working groups in jointly developing scientifically supported restoration and protection strategies. These implementation strategies are intended to meet the TMDL goals outlined in this document.