Total Maximum Daily Load for Total Mercury in the Suwannee Watershed, GA February 28, 2002 TOTAL MAXIMUM DAILY LOAD (TMDL) DEVELOPMENT For Total Mercury In the Suwannee Watershed Including Listed Segments of the Suwannee River: Suwannee Canal - Okefenokee Swamp Suwannee River Mainstem: Suwannee Canal to State Line Total Maximum Daily Load for Total Mercury in the Suwannee Watershed, GA February 28, 2002 TOTAL MAXIMUM DAILY LOAD (TMDL) Total Mercury in Fish Tissue Residue In the In the Suwannee River Watershed Under the authority of Section 303(d) of the Clean Water Act, 33 U.S.C. 1251 et seq., as amended by the Water Quality Act of 1987, P.L. 100-4, the U.S. Environmental Protection Agency is hereby establishing a TMDL for total mercury for the protection of public health associated with the consumption of fish taken from the following segments of the Suwannee River in Georgia: Suwannee Canal - Okefenokee Swamp Suwannee River Mainstem: Suwannee Canal to State Line The calculated allowable load of mercury that may come into the identified segments of the Suwannee River without exceeding the applicable water quality standard is 2.6 kilograms per year. The applicable water quality standard is the State of Georgia’s numeric interpretation of their narrative water quality standard for protection of human health from toxic substances. This interpretation indicates that the consumption of fish by the general population is not to exceed 0.3 mg/kg mercury in fish tissue. Based on a current estimated loading of 6.1 kilograms per year, an estimated 58% reduction in mercury loading is needed for the identified sections of the Suwannee River to meet the applicable water quality standard of 2.8 nanograms per liter (ng/l). This TMDL shall become effective immediately, and is incorporated into the Continuing Planning Process for the State of Georgia under Sections 303(d)(2) and 303(e) of the Clean Water Act. Signed this _________ day of___________, 2002. _____________________________ Beverly H. Banister, Director Water Management Division ii Total Maximum Daily Load for Total Mercury in the Suwannee Watershed, GA February 28, 2002 Table of Contents 1. Introduction............................................................................................................................. 1 2. Phased Approach to the TMDL .............................................................................................. 1 2.1. Phased Approach to Atmospheric Sources ..................................................................... 2 2.2. Phased Approach to Water Point Sources ...................................................................... 2 3. Problem Definition.................................................................................................................. 4 4. Applicable Water Quality Standard ........................................................................................ 5 5. TMDL Target .......................................................................................................................... 6 6. Background ............................................................................................................................. 7 6.1. Source Assessment.......................................................................................................... 9 6.2. Watershed Background Load........................................................................................ 10 6.2.1. RELMAP Mercury Deposition Rates ..................................................................10 6.2.2. Mercury Deposition Network ..............................................................................12 6.3. Available Monitoring Data ........................................................................................... 13 6.3.1. EPA Region 4 Data..............................................................................................14 6.3.2. Water Column Data .............................................................................................14 6.3.3. Sediment/Soil Data ..............................................................................................15 6.3.4. Fish Tissue Data...................................................................................................15 7. Numeric Targets and Sources - Model Development ........................................................... 16 7.1. Watershed Hydrologic and Sediment Loading Model.................................................. 16 7.2. Water Quality Fate and Transport Model ..................................................................... 17 8. Total Maximum Daily Load (TMDL)................................................................................... 18 8.1. Critical Condition Determination ................................................................................. 18 8.2. Seasonal Variation ........................................................................................................ 18 8.3. Margin of Safety ........................................................................................................... 18 9. TMDL Development............................................................................................................. 19 9.1. Model Results ............................................................................................................... 19 iii Total Maximum Daily Load for Total Mercury in the Suwannee Watershed, GA February 28, 2002 9.1.1. Nonpoint Source ..................................................................................................19 9.1.2. Water Quality Model ...........................................................................................21 9.2. TMDL Determination ................................................................................................... 24 10. Allocation of Loads........................................................................................................... 25 10.1. Atmospheric Reductions............................................Error! Bookmark not defined. 10.2. Allocation to NPDES Point Sources..........................Error! Bookmark not defined. 10.3. Implementation ..........................................................Error! Bookmark not defined. 10.4. State and Federal Responsibility................................Error! Bookmark not defined. 11. References......................................................................................................................... 35 12. Appendix A. Analysis of Atmospheric Deposition of Mercury........................................ 37 iv Total Maximum Daily Load for Total Mercury in the Suwannee Watershed, GA February 28, 2002 Table of Figures Figure 1 Suwannee Watershed........................................................................................................ 7 Figure 2 Suwannee Watershed Delineation.................................................................................... 8 Figure 3 Suwannee Watershed Landuses........................................................................................ 9 Figure 4 Mercury Dry Deposition Rates as Reported in the Mercury Report to Congress........... 11 Figure 5 Mercury Wet Deposition Rates as Reported in the Mercury Report to Congress.......... 12 Figure 6 Mercury Deposition Network Sampling Locations ........................................................ 13 Figure 7 Suwannee Watershed Sample Locations........................................................................ 14 Figure 8 Mercury Load Distribution ............................................................................................. 21 v Total Maximum Daily Load for Total Mercury in the Suwannee Watershed, GA February 28, 2002 Table of Tables Table 1 Georgia Department of Natural Resources Fish Consumption Guideline......................... 4 Table 2 Permitted Facilities in Suwannee Watershed................................................................... 10 Table 3 Water Column Mercury Concentrations.......................................................................... 15 Table 4 Sediment/Soil Mercury Concentrations........................................................................... 15 Table 5 Fish Tissue Mercury Data................................................................................................ 16 Table 6 Annual Average Total Mercury Load from each Sub Basin............................................ 20 Table 7 Specified and Calculated Reaction Rates and Coefficients ............................................. 22 Table 8 Flows, Depths, Velocities and Volumes used in WASP Model...................................... 23 Table 9 Predicted and Observed Mercury Concentrations under Annual Average Load and Flow24 Table 10 NPDES Permitted Facilities........................................................................................... 28 vi Total Maximum Daily Load for Total Mercury in the Suwannee Watershed, GA February 28, 2002 1. Introduction The U.S. Environmental Protection Agency (EPA) Region 4 is proposing this Total Maximum Daily Load (TMDL) for total mercury for two listed segments of the Suwannee River Basin. The listed segments are as follows: · Suwannee Canal - Okefenokee Swamp · Suwannee River Mainstem: Suwannee Canal to State Line These segments are included on the State of Georgia’s 2000 Section 303(d) list of impaired waters because mercury in certain species of fish tissue exceeds the Georgia Department of Natural Resources