Northeast Regional Mercury Total Maximum Daily Load Connecticut Department of Environmental Protection Maine Department of Environmental Protection Massachusetts Department of Environmental Protection New Hampshire Department of Environmental Services New York State Department of Environmental Conservation Rhode Island Department of Environmental Management Vermont Department of Environmental Conservation New England Interstate Water Pollution Control Commission October 24, 2007 Contents Contents .......................................................................................................................................................ii Tables ..........................................................................................................................................................iv Figures.........................................................................................................................................................iv Acknowledgements .....................................................................................................................................v Executive Summary ...................................................................................................................................vi Abbreviations ...........................................................................................................................................xiii Definition of Terms..................................................................................................................................xvi 1 Introduction..............................................................................................................................................1 1.1 Water Quality and Health Concerns...............................................................................................1 1.2 TMDL Requirements and Process ..................................................................................................1 2 Background Information.........................................................................................................................2 2.1 Fish Consumption Advisories ..........................................................................................................2 2.2 Section 319 Nonpoint Source Assessments and Categorization of Atmospheric Deposition as a Nonpoint Source......................................................................................................................................3 2.3 Massachusetts’ TMDL Alternative and EPA Justification for Disapproval ...............................4 2.4 Section 303(d) Listing for Mercury Impaired Waters – Category 5m.........................................5 2.5 Northeast Regional Commitment to Reducing Regional Sources of Mercury............................6 2.6 Control of In-State Sources not Sufficient to Meet Water Quality Standards............................7 3 Applicable Water Quality Standards and Fish Tissue Criteria...........................................................8 3.1 Assessment of Fish Contaminants ...................................................................................................8 4 Fish Tissue Mercury Concentrations .....................................................................................................9 4.1 Fish Tissue Monitoring Dataset.......................................................................................................9 4.2 Areas of Elevated Concentration...................................................................................................11 5 Northeast Regional Approach...............................................................................................................11 5.1 Impaired Waters .............................................................................................................................11 5.2 Priority Ranking of Impaired Waterbodies .................................................................................12 5.3 Selection of Existing Fish Mercury Concentration Based on Standard Size Fish.....................13 5.4 Target Fish Mercury Concentration.............................................................................................15 5.5 Proportionality of Mercury Reductions........................................................................................16 6 Source Assessment .................................................................................................................................18 6.1 Northeast States Emissions Inventory...........................................................................................18 6.2 Atmospheric Deposition Modeling ................................................................................................22 6.3 Point Sources to Water...................................................................................................................25 7 Development of a Regional Total Maximum Daily Load...................................................................26 7.1 TMDL Formulation ........................................................................................................................26 7.2 Calculation of Existing Total Source Load (TSL)........................................................................27 7.3 Reduction Factor (RF)....................................................................................................................28 7.4 TMDL Calculation..........................................................................................................................29 7.5 Wasteload Allocation (WLA).........................................................................................................29 7.6 Load Allocations..............................................................................................................................30 7.6.1 Load Allocation Calculations..................................................................................................30 7.6.2 Necessary Reductions to Meet LA..........................................................................................31 7.7 Margin of Safety..............................................................................................................................33 7.8 Seasonal Variation and Critical Conditions .................................................................................34 7.9 Daily Load........................................................................................................................................34 8 Final TMDL............................................................................................................................................34 9 Implementation ......................................................................................................................................35 Northeast Regional Mercury TMDL – October 2007 ii 9.1 State and Regional Implementation ..............................................................................................35 9.1.1 Implementation of Wasteload Allocation ..............................................................................35 9.1.2 Adaptive Implementation of Load Allocation .......................................................................36 9.2 Adaptive National Implementation ...............................................................................................38 10 Reasonable Assurances........................................................................................................................39 10.1 State Level Assurances .................................................................................................................39 10.2 National and International Assurances.......................................................................................44 11 Public Participation .............................................................................................................................45 12 References.............................................................................................................................................47 Appendix A: Northeast Waters Impaired Primarily by Atmospheric Deposition of Mercury .........50 Appendix B: Necessary Reductions to meet Water Quality Standards in Maine and Connecticut..57 Appendix C: Mean Mercury Concentrations at NPDES-Permitted Facilities Used in Calculating the Baseline Point Source Load......................................................................................................................66 Appendix D: State Mercury Reduction Plans ........................................................................................72 Appendix E: Response to Comments ......................................................................................................73 Northeast Regional Mercury TMDL – October 2007 iii Tables Table ES-1 Summary of Northeast Regional Mercury TMDL………………………………………......viii Table 2-1 Summary of Statewide Fish Consumption Advisories for Freshwaters………………………...3 Table 3-1 Water Quality Criteria and Fish Consumption Advisory Values for Mercury…………..……...8 Table 4-1 Number of Fillet Mercury Samples Included and Mean Length-Standardized Mercury Concentration for Fish Species Analyzed in the NERC Dataset…...…………………………………..…10 Table 4-2 Standard Lengths and Mercury Concentrations of Selected Freshwater Fish Species in the Northeast…………………………………………………………………………………………………..10