Mercury Control Program for the Sacramento-San Joaquin River Delta Estuary

1. Mercury Control Program for the Sacramento-San Joaquin River Delta Estuary San Francisco Bay RMP Annual MeetingOctober 7, 2008 Michelle Wood

2. Outline • Description of the Delta Mercury Impairment • Overview of Proposed Delta Program • Comparison to RMP Mercury Strategy’s High Priority Questions • Questions & Discussion

3. Sacramento Region 5 Region 2 San Francisco BayHg Control Program: ReduceCentral Valley Mercury Outflows by 110 Kg/year Antioch Stockton Brentwood Tracy The Delta >1100 mi waterways Drains ~1/3 of CA

4. Who eats Delta fish? Wildlife: Least tern, kingfisher, western grebes, bald eagle, osprey, & river otter

5. Who eats Delta fish? ~300,000 licensedsport & subsistenceanglers per year Unknown # of unlicensed anglers Multiple ethnicities, communities,& income levels 5% of fish consumers in northern Delta: mercury intake rate 10x the safe dose

6. Goal of the ProposedDelta Mercury Program: Protect fish-eating wildlife& enable humans to safelyconsume more Delta fish.

7. Proposed Fish TissueHg Objective for Delta Fish 0.24 mg/kg mercury in large bass & catfish 1 meal (8 oz)per week

8. Average Hg Levelsin Large Bass & Catfish(mg/kg) 0.56 na 0.92 0.32 0.26 na 0.50 Proposed Objective: 0.24 mg/kg

9. Mercury Strategy for the Bay-Delta Ecosystem (CalFed, 2003): “The problem with mercury in the Delta’s aquatic ecosystems can be defined as biotic exposure to methylmercury.” MeHg = most toxic, bioavailable form of Hg >90% of Hg in fish = MeHg

10. MeHg TributaryMeHg Agricultural Lands / Delta Islands Urban & WWTPs Wetlands Pore WaterExchange & Diffusion OpenChannel Hg MeHg bacterial methylation Surface Sediments

11. How do we reducefish MeHg levels? • Local & nationwide studies: Most important, single factor in determining how much MeHg is in fishis water MeHg concentration • Most direct way to reduce fish MeHg is to reduce the concentration of MeHg in water

12. 1.6374 y = 20.365x MeHg Linkage: Largemouth Bass & Average Water MeHg 1.0 R2 = 0.91 0.5 Bass Hg (mg/kg) 0.0 0.0 0.1 0.2 Water MeHg (ng/l)

13. 1.6374 y = 20.365x 0.24 mg/kg 0.066 ng/l MeHg Linkage: Largemouth Bass & Average Water MeHg 1.0 R2 = 0.91 0.5 Bass Hg (mg/kg) 0.0 0.0 0.1 0.2 Water MeHg (ng/l)

14. Proposed MeHg Goal • 0.06 ng/l in unfiltered ambient water, annual average • Establishes the assimilative capacity • Used to determine how much reduction from MeHg sources is needed to achieve fish tissue objective

15. Average AnnualAmbient MeHg Levelsin Water(ng/l) 0.11 0.27 0.27 0.17 0.08 0.06 0.22 0.16

16. 45% 65% 25% 0% 73% 63% MeHgSource Reductions Needed to Achieve Proposed0.06 ng/l goal 78% 78% 25% 0%

17. Proposed Control Strategy • Reduce Hg in sediment(reduces MeHg produced by Delta wetlands& open-water areas) • Control activities that enhanceproduction of (and degrade) MeHg in wetlands & open-water areas • Reduce MeHg dischargesfrom external sources(e.g., WWTPs, urban runoff & irrigated agriculture)

18. Delta TMDL Adaptive Approach TMDL Review Phase 1 Phase 2 ~2009 ~2017 • Studies • Implement Hg pollution prevention measures • Improve CC Settling Basin • Identify other high-priority legacy Hg projects • Develop upstream TMDLs • Conduct pilot offset projects • Implement MeHg controls in the Delta & upstream watersheds • Continue to implement legacy Hg projects • Long-term offset projects Re-assess MeHg allocations & schedules.

19. Outline • Description of the Delta Mercury Impairment • Overview of the Proposed Delta Program • Comparison to RMP Mercury Strategy’s High Priority Questions • Questions & Discussion

20. RMP Priority Questions • Where and when does mercury enter the food web? • We have a general idea of the “where” in the main channels

21. Lower fish Hgin Central Deltaduring relativelylow-flow years Elevatedfish Hgin Deltaperiphery Lower fish Hgin Central Delta during relativelylow-flow years CalFed Mercury ProgramFish Sampling Inland silverside Hg & MeHg Concentrations, Fall 1999(Slotton et al., 2002) Average Hg Concentrations in largemouth bass, 2000(Davis et al., 2003)

22. RMP Priority Questions • Where and when does mercury enter the food web? • We have a general idea of the “where” in the main channels • Does MeHg uptake into biota occur preferentially during some seasons? • Recent CalFed study results from Darrell Slotton and others indicate increases in biosentinel fish and water MeHg have been associated with floodplain inundation that occurred in different times of the year

23. RMP Priority Questions • Which processes, sources & pathways contribute disproportionately to food-web accumulation? • RMP isotopic composition study of mercury to determine which mercury inputs are contributing most to bioaccumulation • Useful for both Bay & Delta programs! • Compliments the proposed Delta program’s focus on identifying the MeHg sources to the Delta & the inorganic Hg sources that supply the MeHg sources

24. RMP Priority Questions • Which processes, sources, & pathways contribute disproportionately to food-web accumulation? • We have a general idea of which sources contribute MeHg & TotHg to the different areas of the Delta • Sources that cause the impairment in different Delta areas come from different places • We need seven different area-specific control strategies

25. Seven ControlProgramsin One… Yolo Bypass …because different areas of the Deltaare dominated by different MeHg & TotHgsources Southern Delta

26. RMP Priority Questions • Which processes, sources, & pathways contribute disproportionately to food-web accumulation? • Need to refine load estimates for wetlands in the Delta & upstream watersheds

27. RMP Priority Questions • What are the best opportunities for management intervention for the most important pollutant sources, pathways & processes? • What are the effects of management actions? Proposed Delta TMDL implementation plan includes studies to address these questions. Yolo Bypass wetland management practice study is already underway

28. RMP Priority Questions Questions 3 & 4 Key observations for the Delta: • Tributary watersheds account for most of the MeHg inputs to the Delta • No one point or nonpoint source - individual or by category - in the Delta or its upstream watersheds causes the impairment

29. RMP Priority Questions Questions 3 & 4 Key observations for the Delta: • All wetlands are not alike: some act as big sources, some as small sources, and some as sinks • All WWTPs are not alike: some have low effluent MeHg, others high

30. RMP Priority Questions Questions 3 & 4 Key observations for the Delta: • Two recent studies support the hypothesis that MeHg in ambient water is a primary factor in determining how much MeHg is in fish

31. (1) Floodplain Inundation on theSan Joaquin River: Before & After

32. RMP Priority Questions Questions 3 & 4 Key observations for the Delta: • Two recent studies support the hypothesis that MeHg in ambient water is a primary factor in determining how much MeHg is in fish • Local bioaccumulation study: WWTP effluent contributes about the same amount of mercury to Sacramento River bioaccumulation as expected from its effluent methylmercury loads

33. RMP Priority Questions Questions 3 & 4 Proposed Delta control program does not attempt to indicate which MeHg sources are more important because: • No one source type or individual source causes the impairment • We need additional characterization studies, especially for wetlands • We don’t know yet which inorganic Hg & MeHg sources will be the most feasible to reduce [in terms of efficacy, economics & environmental impacts associated with particular controls and management practices]

34. RMP Priority Questions • Will total mercury reductions result in reduced food web accumulation? Another good question! Further, if “yes”, can we reduce total Hg sources enough to accomplish desired fish MeHg reductions?

35. Questions & Comments Updates, reports & comments: http://www.waterboards.ca.gov/centralvalley/ water_issues/tmdl/central_valley_projects/delta_hg/