Thief River Watershed Total Maximum Daily Load A description of the restoration measures necessary to bring the Thief River and its tributaries into compliance with Minnesota water quality standards for total suspended solids and E. coli. March 2019 wq-iw5-11e Authors and contributors: Corey Hanson, Red Lake Watershed District Water Quality Coordinator Denise Oakes, Minnesota Pollution Control Agency Stephanie Klamm, Minnesota Department of Natural Resources Matthew Fisher, Minnesota Board of Soil and Water Resources Peter Nelson, Pennington County Soil and Water Conservation District Jason Vinje, Minnesota Department of Natural Resources Lori Clark, Minnesota Department of Natural Resources Reed Larson, Minnesota Pollution Control Agency Jim Courneya, Minnesota Pollution Control Agency Molly MacGregor, Minnesota Pollution Control Agency Thief River Watershed TMDL Minnesota Pollution Control Agency Contents Contents ............................................................................................................................................3 List of Tables ......................................................................................................................................6 List of Figures .....................................................................................................................................7 Acronyms ........................................................................................................................................ 10 Executive Summary .......................................................................................................................... 12 1. Project Overview ...................................................................................................................... 13 1.1 Purpose .............................................................................................................................................. 13 1.2 Identification of Waterbodies ............................................................................................................ 13 1.3 Priority Ranking .................................................................................................................................. 16 2. Applicable Water Quality Standards and Numeric Water Quality Targets ................................... 17 2.1 Dissolved Oxygen ............................................................................................................................... 17 2.2 Turbidity ............................................................................................................................................. 18 2.3 Total Suspended Solids ...................................................................................................................... 19 2.4 Escherichia coli (E. coli) ...................................................................................................................... 21 3. Watershed and Waterbody Characterization ............................................................................. 22 3.1 Streams .............................................................................................................................................. 24 3.2 Impoundments and Reservoirs .......................................................................................................... 27 3.3 Subwatersheds ................................................................................................................................... 31 3.4 Land Use ............................................................................................................................................. 36 3.5 Current/Historic Water Quality .......................................................................................................... 41 3.5.1 Turbidity and Total Suspended Solids in the Thief River .................................................... 43 3.5.2 Dissolved Oxygen in the Mud River .................................................................................... 46 3.5.3 E. coli in the Mud River ....................................................................................................... 49 3.5.4 Dissolved Oxygen in the Moose River ................................................................................. 51 3.6 Pollutant Source Summary ................................................................................................................. 54 3.6.1 Turbidity/Total Suspended Solids in the Lower Thief River ................................................ 54 3.6.1.1 Regulated Sources ........................................................................................................... 54 3.6.1.2 Non-permitted Sources ................................................................................................... 55 3.6.2 E. coli Bacteria in the Mud River ......................................................................................... 70 3.6.2.1 Permitted Sources ........................................................................................................... 70 3.6.2.2 Non-permitted Sources ................................................................................................... 72 3.6.3 Low Dissolved Oxygen (DO) in the Mud River .................................................................... 76 3.6.3.1 Permitted Sources ........................................................................................................... 80 3.6.3.2 Non-permitted Sources ................................................................................................... 80 Thief River Watershed TMDL Minnesota Pollution Control Agency 3 3.6.4 Low Dissolved Oxygen (DO) due to Lack of Flow in the Moose River................................. 81 3.6.4.1 Permitted Sources ........................................................................................................... 84 3.6.4.2 Non-permitted Sources ................................................................................................... 84 4. TMDL Development .................................................................................................................. 89 4.1 Total Suspended Solids in the Thief River (AUID 09020304-501) ...................................................... 89 4.1.1 Loading Capacity Methodology .......................................................................................... 89 4.1.2 Load Allocation Methodology ............................................................................................. 90 4.1.3 Wasteload Allocation Methodology ................................................................................... 91 4.1.4 Margin of Safety .................................................................................................................. 92 4.1.5 Seasonal Variation .............................................................................................................. 92 4.1.6 Reserve Capacity ................................................................................................................. 94 4.1.7 TMDL Summary ................................................................................................................... 94 4.2 E. coli bacteria in the Mud River (AUID 09020304-507) .................................................................... 95 4.2.1 Loading Capacity Methodology .......................................................................................... 95 4.2.2 Load Allocation Methodology ............................................................................................. 96 4.2.3 Wasteload Allocation Methodology ................................................................................... 97 4.2.4 Margin of Safety .................................................................................................................. 97 4.2.5 Seasonal Variation .............................................................................................................. 97 4.2.6 Reserve Capacity ................................................................................................................. 98 4.2.7 TMDL Summary ................................................................................................................... 98 5. Future Growth Considerations ................................................................................................ 100 5.1 New or Expanding Permitted MS4 WLA Transfer Process ............................................................... 100 5.2 New or Expanding Wastewater........................................................................................................ 100 6. Reasonable Assurance ............................................................................................................ 101 7. Monitoring Plan ...................................................................................................................... 104 8. Implementation Strategy ........................................................................................................ 108 8.1 Permitted Sources ............................................................................................................................ 108 8.1.1 MS4 ................................................................................................................................... 108 8.1.2 Wastewater ......................................................................................................................