Watershed September 2021 Otter Tail River Watershed Restoration and Protection Strategy Report Authors Moriya Rufer, MS, CLM, Houston Engineering, Inc. Scott Kronholm, PhD, Houston Engineering, Inc. 7550 Meridian Circle North, Maple Grove, MN 55369 Contributors/acknowledgements Darren Newville and Ben Underhill East Otter Tail Soil and Water Conservation District 801 Jenny Ave SW, Ste #2, Perham, MN 56573 Scott Schroeder and Danielle Kvasager Minnesota Pollution Control Agency 714 Lake Ave, Ste 220, Detroit Lakes, MN 56501 Timothy Erickson and Lori Han Houston Engineering 7550 Meridian Circle North, Maple Grove, MN 55369 Watershed Partners: Thank you to the contributing Watershed Partners in the Otter Tail River Watershed that contributed to this document: Becker County Becker Soil and Water Conservation District Board of Water and Soil Resources Buffalo Red River Watershed District Cormorant Lakes Watershed District East Otter Tail Soil and Water Conservation District Minnesota Department of Natural Resources Minnesota Pollution Control Agency Otter Tail County Pelican River Watershed District Tamarac National Wildlife Refuge West Otter Tail Soil and Water Conservation District Wilkin County Wilkin Soil and Water Conservation District Editing and graphic design Dan Olson Cover photo credit: Jinny Fricke Detroit Lake. Detroit Lakes, Minnesota. July 1, 2019 Courtesy of Moriya Rufer. The MPCA is reducing printing and mailing costs by using the Internet to distribute reports and information to a wider audience. Visit our website for more information. The MPCA reports are printed on 100% post-consumer recycled content paper manufactured without chlorine or chlorine derivatives. Document number: wq-ws4-82a Contents List of Tables ................................................................................................................................................. ii List of Figures............................................................................................................................................... iii Key terms ..................................................................................................................................................... iv Abbreviations ............................................................................................................................................... v Executive summary ............................................................................................................................ vii What is the WRAPS report? ........................................................................................................................ ix 1. Watershed background and description ....................................................................................... 1 2. Watershed conditions .................................................................................................................. 4 Condition status ................................................................................................................................. 7 Water quality trends ........................................................................................................................ 24 Stressors and sources ....................................................................................................................... 29 TMDL summary ................................................................................................................................ 42 Protection considerations ................................................................................................................ 45 3. Prioritizing and implementing restoration and protection .......................................................... 61 Targeting of geographic areas .......................................................................................................... 62 Climate change considerations ........................................................................................................ 75 Public participation .......................................................................................................................... 77 Restoration and protection strategies ............................................................................................. 80 4. Monitoring plan ....................................................................................................................... 125 5. References and further information ......................................................................................... 127 6. Appendices .............................................................................................................................. 129 Otter Tail River WRAPS Report Minnesota Pollution Control Agency i List of Tables ____________________________________________________________________________________________________________________________________________________________ Table 1. Assessment status of river reaches in the OTRW. .......................................................................... 9 Table 2. Impaired stream reaches in the OTRW. ........................................................................................ 13 Table 3. Assessment status of lakes in the OTRW. ..................................................................................... 15 Table 4. Impaired lakes in the OTRW1. ....................................................................................................... 23 Table 5. Water quality trends of the sampled streams within the OTRW1 ................................................ 25 Table 6. Water quality trends of the sampled lakes within the OTRW1 ..................................................... 25 Table 7. Total Phosphorus, Chlorophyll-a, and Secchi trends within the lakes of the OTRW. ................... 26 Table 8. Summary of common biotic stressors assessed as potential candidate causes for the biologically impaired reaches within the OTRW. ........................................................................................................... 30 Table 9. Primary stressors to aquatic life in biologically impaired stream reaches in the OTRW. ............. 31 Table 10. Summary of common biotic stressors assessed as potential candidate causes for the biologically impaired lakes within the OTRW. ............................................................................................ 32 Table 11. Primary stressors to aquatic life in biologically impaired lakes in the OTRW. ............................ 33 Table 12. Nonpoint sources in the OTRW.1 ................................................................................................ 36 Table 13. Point sources in the OTRW.1 ....................................................................................................... 40 Table 14. TMDL summary for all streams being addressed with TMDLs in the OTRW. ............................. 43 Table 15. TMDL summary for all lakes being addressed with TMDLs in the OTRW. .................................. 44 Table 16. Protection and Restoration Classifications in Streams in the OTRW. ......................................... 46 Table 17. Stream protection and prioritization. ......................................................................................... 48 Table 18. OTRW Lake Prioritization Summary for TP risk. .......................................................................... 50 Table 19. Lake phosphorus load management focus (HSPF)1 ..................................................................... 57 Table 20. Summary of the stressors associated with the biologically vulnerable lakes in the OTRW........ 61 Table 21. Fair share load reduction goals for the OTRW. ........................................................................... 64 Table 22. Additional tools available for restoration and protection of impaired and nonimpaired waters. .................................................................................................................................................................... 72 Table 23. BMPs implemented in the OTRW between 2004-2019 (MPCA 2020a and PRWD 2020). .......... 85 Table 24. Strategies and actions proposed for the OTRW. ......................................................................... 87 Table 25. Strategies that can be implemented to meet or help meet water quality goals in the OTRW. 105 Table 26. A variety of BMPs which can be used to target and improve various water quality parameters. .................................................................................................................................................................. 107 Otter Tail River WRAPS Report Minnesota Pollution Control Agency ii List of Figures ____________________________________________________________________________________________________________________________________________________________ Figure 1. Photo of Pelican Lake. ...................................................................................................................... Figure 2. Diagram of the watershed cycle in Minnesota. ............................................................................ ix Figure 3. Land use within the OTRW. .............................................................................................................. Figure 4. Detroit Lake. ..................................................................................................................................