Completing the SF Bay Mercury TMDL Carrie Austin SF Bay Water Board

1. Completing the SF Bay Mercury TMDLCarrie AustinSF Bay Water Board

2. Overview of Water Board Response • More Stringent Requirements for Wastewater • New Water Quality Objectives • Actions to clarify and improve implementation

3. Mercury Loads and Allocations

4. Wastewater [Hg]T “Trigger” • Standard NPDES permit calculation • Performance based: Mean + 3 SDs • About 99th percentile • Triggers for “advanced” & “secondary”

5. Wastewater Individual WLAs • Calculated differently • Performance-based • 99% UCL on the Mean • Sum of Individual WLAs = “group trigger”

6. Revised Wastewater Allocations Current allocations(kg/year) Revisedallocations 17 11? 99% UCL on the mean = 20 kg/yr annual average

7. New Water Quality Objectives • Vacate water column objective0.025 ug/L4-day average • Establish two new fish tissue objectives:0.2 ppm larger fish0.03 ppm smaller prey fish Second fish tissue objectives in California – Clear Lake was first.

8. Timeline and Next Steps • Release documents for public review mid-March • Public review period through April • Water Board action in June

9. Guadalupe River Watershed Mercury TMDL Carrie Austin SF Bay Water Board

10. Debut: GRW Hg TMDL Public Comment period closes 06/30/06 Documents available from: http://www.waterboards.ca.gov/sanfranciscobay/guadaluperivermercurytmdl.htm • TMDL Project Report Jan06 • Final Conceptual Model Report May05 • Derivation Numeric Wildlife Targets Apr05

11. TMDL Overview • Problem • Sources • Targets • Allocations • Implementation

12. Problem: Bioaccumulation Summary of 2004 Fish Sampling Results Citation: Figure 3-25 Final Conceptual Model Report(Tetra Tech 2005c)

13. Sources • Mining Waste • Urban Runoff • Atmospheric Deposition • Natural Hg in soil Citation: figure by Tetra Tech

14. Mining Waste Erodes into: Predominantly Alamitos Creek & Lake Almaden Canal from Almaden  Calero Reservoir Jacques Gulch into Almaden Reservoir Small area into Guadalupe Reservoir Remainder into Guadalupe Creek

15. TARGETS

16. Numeric Targets = “Fishable”

17. Achievable Targets • Ore – underground • Cinnabar outcrops on Mine Hill • Cinnabar nuggets in Deep Gulch • No deep lakes Hypothesis: low mercury bioaccumulation pre-mining

18. ALLOCATIONS

19. “Impoundments” Impoundments are engineered structures that pond water. • dams (i.e., reservoirs and artificial lakes), • flood control structures, • other engineered features (such as drop structures), and • non-native invasive vegetation that ponds water

20. Fish in Reference Reservoir Fishable: • 40-cm Largemouth bass: 0.6 ppm < 0.66 ppm TL4 human health target • Age-1 Largemouth bass: 0.09 ppm @ 89 mm length, equals 0.045 in TL3 < 0.05 ppm wildlife target

21. Allocation: Hypolimnion MeHg

22. Downstream Implications Figure 6.7 Dissolved Methylmercury Below Reservoirs, July 2003 Citation: Figure 5-10 Final Conceptual Model Report (Tetra Tech 2005)

23. Lower [Hg]sed Lower [Hg]fish

24. Allocations based on Reference Reservoir

25. IMPLEMENTATION

26. Start in Headwaters: New Almaden 0.1 ppm mercury in erodable soil finestransportedin runoff BMPs for erosion control w/in 10 yrs

27. Impoundment MeHg Production Thermal stratification (natural, good) Low DO in hypolimnion SRB produce HS-which dissolves mining waste SRB produce MeHg

28. Is Oxygen the Solution to MeHg? Thermal stratification (natural, good) oxygenated hypolimnion

29. Dissolved Hg Hypotheses • Wet season:HgDiss transported in storm water from mining waste quickly attaches to particulates; erosion control sufficient. • Dry season:main concern with HgDiss is dry season dissolution of mining waste under anoxic conditions

30. Summary Figure S-1 Solving the Mercury Problem Citation: figure prepared by Tetra Tech

31. Comments on Guad Hg TMDL Public Comment period ends June 30send to:Carrie AustinSF Bay Water Board1515 Clay Street, #1400Oakland, CA 94612 caustin@waterboards.ca.gov