Mercury Control Program for the SacramentoSan Joaquin River Delta Estuary

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

• San Francisco Bay RMP Annual MeetingOctober 7,
  2008
• Michelle Wood

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Outline

• Description of the Delta Mercury Impairment
• Overview of Proposed Delta Program
• Comparison to RMP Mercury Strategys High
  Priority Questions
• Questions Discussion

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The Delta
1100 mi waterways Drains 1/3 of CA
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Who eats Delta fish?
Wildlife Least tern, kingfisher, western grebes,
bald eagle, osprey, river otter
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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

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Goal of the ProposedDelta Mercury Program

• Protect fish-eating wildlife enable humans to
  safelyconsume more Delta fish.

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Proposed Fish TissueHg Objective for Delta Fish
0.24 mg/kg mercury in large bass catfish
1 meal (8 oz)per week
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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
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Mercury Strategy for the Bay-Delta Ecosystem
(CalFed, 2003)
The problem with mercury in the Deltas aquatic
ecosystems can be defined as biotic exposure to
methylmercury.
MeHg most toxic, bioavailable form of Hg 90
of Hg in fish MeHg
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MeHg
Surface
Sediments
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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

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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)
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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)
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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

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Average AnnualAmbient MeHg Levelsin Water(ng/l)
0.11
0.27
0.27
0.17
0.08
0.06
0.22
0.16
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MeHgSource Reductions Needed to Achieve
Proposed0.06 ng/l goal
78
78
25
0
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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)

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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.
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Outline

• Description of the Delta Mercury Impairment
• Overview of the Proposed Delta Program
• Comparison to RMP Mercury Strategys High
  Priority Questions
• Questions Discussion

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RMP Priority Questions

• Where and when does mercury enter the food web?
• We have a general idea of the where in the main
  channels

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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)
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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

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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 programs focus on
  identifying the MeHg sources to the Delta the
  inorganic Hg sources that supply the MeHg sources

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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

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Seven ControlProgramsin One
Yolo Bypass

• because different areas of the Deltaare
  dominated by different MeHg TotHgsources

Southern Delta
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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

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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
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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

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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

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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

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(1) Floodplain Inundation on theSan Joaquin
River Before After
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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

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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 dont 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

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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?
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Questions Comments

• Updates, reports comments
• http//www.waterboards.ca.gov/centralvalley/
• water_issues/tmdl/central_valley_projects/delta_hg
  /

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