Enclosure 1 Michigan Statewide Mercury Total Maximum Daily Load June 2018 Prepared for: Michigan Department of Environmental Quality and United States Environmental Protection Agency Region 5 By: LimnoTech Under Subcontract to: Battelle Duxbury, Massachusetts USEPA Contract No. EP-C-08-001 Task Order 006 TABLE OF CONTENTS EXECUTIVE SUMMARY ...........................................................................................................8 1 INTRODUCTION..................................................................................................................10 2 BACKGROUND ....................................................................................................................12 2.1 PROBLEM STATEMENT ................................................................................................12 2.1.1 TMDL DEVELOPMENT PROCESS ............................................................................15 2.1.2 RECENT MERCURY TRENDS ....................................................................................16 2.2 DATA COLLECTION AND ASSESSMENT OF WATER QUALITY ..........................19 2.2.1 DATA COLLECTION AND SUMMARY ANALYSIS .......................................................19 2.2.2 DISCUSSION OF SECTION 303(D) LISTINGS .............................................................23 2.3 SCOPE OF WATER BODIES CONSIDERED UNDER THIS TMDL ...........................26 3 APPLICABLE WQS AND NUMERIC TARGETS ...........................................................27 3.1 DESIGNATED USES AND WATER QUALITY CRITERIA ........................................27 3.2 NUMERIC TMDL TARGET ............................................................................................27 4 MODELING APPROACH ...................................................................................................29 4.1 RELATING ATMOSPHERIC LOADING TO FISH TISSUE CONCENTRATION .....29 4.2 ATMOSPHERIC DEPOSITION OF MERCURY ............................................................30 4.3 APPLYING THE NUMERIC TMDL TARGET ..............................................................38 4.3.1 SELECTION OF A TARGET FISH SPECIES ..................................................................39 4.3.2 SELECTION OF A STATISTICAL LEVEL FOR DEFINING TMDL REDUCTIONS ............40 4.4 REGIONALIZATION .......................................................................................................41 4.5 REQUIRED OVERALL REDUCTION PERCENTAGE.................................................42 5 SOURCE ASSESSMENT .....................................................................................................44 5.1 MERCURY SOURCE CATEGORIES .............................................................................44 5.1.1 NATURAL SOURCES ................................................................................................45 5.1.2 ANTHROPOGENIC SOURCES.....................................................................................45 5.2 COMPILATION OF SOURCE DATA .............................................................................48 5.2.1 DATA GAP ANALYSIS .............................................................................................49 5.2.2 NPS OF MERCURY ..................................................................................................50 5.2.3 POINT SOURCES OF MERCURY TO WATER ..............................................................51 5.2.4 MERCURY PERMITTING STRATEGY FOR POINT SOURCES ........................................52 6 TMDL DEVELOPMENT .....................................................................................................54 6.1 BASELINE MERCURY LOAD .......................................................................................54 6.1.1 BASELINE NPS LOAD .............................................................................................55 6.1.2 BASELINE POINT SOURCE LOAD .............................................................................55 6.1.3 BASELINE TSL ........................................................................................................56 6.2 TMDL CALCULATION ...................................................................................................56 6.3 WLA ................................................................................................................................56 6.4 LA ................................................................................................................................57 LimnoTech Page ii 6.5 MOS ................................................................................................................................60 6.6 CRITICAL CONDITIONS AND SEASONAL VARIATION .........................................60 7 REASONABLE ASSURANCE AND IMPLEMENTATION ............................................61 7.1 CLEANUP OF LEGACY SOURCES ...............................................................................61 7.2 VOLUNTARY ACTIVITIES ............................................................................................61 7.2.1 MICHIGAN MERCURY STRATEGY ............................................................................61 7.2.3 MERCURY MONITORING .........................................................................................63 7.3 REGULATORY ACTIVITIES .........................................................................................63 7.3.1 AIR - STATE ............................................................................................................63 7.3.2 AIR - FEDERAL ........................................................................................................64 7.3.3 MICHIGAN LEGISLATION TO REDUCE MERCURY WASTE ........................................65 7.3.4 NPDES PROGRAM CONTROL OF MERCURY TO SURFACE WATERS ........................66 8 POST-TMDL MONITORING .............................................................................................67 8.1 MDEQ MONITORING .....................................................................................................67 8.1.1 FCMP .....................................................................................................................67 8.1.2 WCMP ...................................................................................................................67 8.1.3 NPDES MONITORING PROGRAM ............................................................................68 8.2 ATMOSPHERIC EMISSION INVENTORY ...................................................................68 8.3 ATMOSPHERIC MERCURY MONITORING ................................................................69 8.4 BIOSOLIDS MONITORING ............................................................................................69 8.5 NEW MONITORING AND ASSESSMENT DATA .......................................................70 8.6 TMDL REVISION.............................................................................................................70 9 REFERENCES .......................................................................................................................71 LimnoTech Page iii LIST OF FIGURES Figure ES-1. Assessed and Mercury-Impaired Water Body Segments in Michigan………………………………………………………..… .................................. 2 Figure 1. Mercury Processes in the Environment. ......................................................................... 13 Figure 2. The Mercury Cycle. Source: MDEQ, 2008a. .................................................................. 14 Figure 3. The MDEQ’s 5-year Rotating Watershed Monitoring Cycle. ........................................... 16 Figure 4. Annual Mercury Wet Deposition (µg/m2/yr) from Event Precipitation Samples, 1995-2005. ............................................................................................................................... 17 Figure 5. Mercury-impaired Rivers and Streams (a) and Lakes (b), Based on Fish Tissue Data. .. 24 Figure 6. Mercury-impaired Rivers and Streams Based on Water Column Data. .......................... 25 Figure 7. Mercury Deposition Predicted for Michigan (2001) by the REMSAD Model. ................... 31 Figure 8. EDUs in Michigan. .......................................................................................................... 33 Figure 9. Modeled Mercury Deposition Rate by EDU for 2001 Conditions. .................................... 35 Figure 10. Weather Research and Forecasting Model Modeling Domains. ................................... 36 Figure 11. Comparison of Modeled and Measured Precipitation for Select Locations for Calendar Year 2005 Weather Research and Forecasting Model BASE CASE Simulation...... 37 Figure 12. Summed Annual (2005) CMAQ Model BASE CASE Simulation Mercury Wet and Dry Deposition (μg/m2) at a Select Series of Locations Across the State of Michigan. .. 38 Figure 13. Photo of a Northern Pike. ............................................................................................. 39 Figure 14. A Regression of Fish Length versus Fish Tissue Concentrations for Northern Pike from Torch Lake in Houghton County, Michigan.............................................................. 40 Figure 15. Cumulative Distribution of Length-Standardized Mercury Concentrations in Northern Pike......................................................................................................................... 41 Figure 16. Average Mercury Concentration in Edible Portions of Northern