Slide 1

Mercury Control Program for the Sacramento-San Joaquin

River Delta Estuary

San Francisco Bay RMP Annual Meeting

October 7, 2008

Michelle Wood

Slide 2

OutlineDescription of the Delta Mercury

ImpairmentOverview of Proposed

Delta Program

Comparison to RMP Mercury Strategy’s High Priority Questions

Questions & Discussion

Slide 3

The Delta

R

S

F

>1100 mi waterwaysDrains ~1/3 of CA

Reg

ion

5

Sacramento

Tracy

StocktonAntioch

Brentwood

Reg

ion

2

San Francisco BayHg Control Program:

ReduceCentral Valley

Mercury Outflows by 110 Kg/year110 Kg/year

Slide 4

Who eats Delta fish?

Wildlife:

Least tern, kingfisher, western grebes, bald eagle, osprey,

& river otter

Slide 5

Who eats Delta fish?

~300,000 licensedsport & subsistence

anglers 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

Slide 6

Goal of the ProposedDelta Mercury Program:

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

Slide 7

Proposed Fish TissueHg Objective for Delta Fish

0.24 mg/kg mercuryin large bass & catfish

1 meal (8 oz)

per week

Slide 8

Average Hg Levelsin Large Bass & Catfish(mg/kg)

0.26na

0.50

0.56

0.92

na

0.32

Proposed Objective:

0.24 mg/kg

Slide 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

Slide 10

TributaryMeHg

Surface

Sediments

Pore WaterExchange &

Diffusion

bacterial methylation

Hg MeHg

MeHg

OpenChannel

Wetlands

Urban & WWTPs

Agricultural Lands /Delta Islands

Slide 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

Slide 12

MeHg Linkage: Largemouth Bass & Average Water MeHg

R2 = 0.91

0.0

0.5

1.0

0.0 0.1 0.2

Water MeHg (ng/l)

Bas

s H

g (m

g/kg

)

y = 20.365x 1.6374

Slide 13

MeHg Linkage: Largemouth Bass & Average Water MeHg

R2 = 0.91

0.0

0.5

1.0

0.0 0.1 0.2

Water MeHg (ng/l)

Bas

s H

g (m

g/kg

)

0.24 mg/kg

0.066 ng/l

y = 20.365x 1.6374

Slide 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

Slide 15

0.16

0.11

0.17

0.08

0.22

Average Annual

Ambient MeHg Levels

in Water(ng/l)

0.06

0.270.27

Slide 16

MeHgSource

Reductions Needed to Achieve

Proposed0.06 ng/l goal

78%

0%

63%

45%

65%

73%

25%0%

25%

78%

Slide 17

Proposed Control StrategyReduce 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)

Slide 18

Delta TMDL Adaptive Approach

~2009 Phase 1 Phase 2

Studies

Implement Hg pollution prevention measures

Improve CC Settling Basin

Identify other high-priority legacy Hg projects

Develop upstream TMDLs

Conduct pilot offset projects

Re-

asse

ss M

eHg

Re-

asse

ss M

eHg

allo

catio

ns &

sch

edul

es.

allo

catio

ns &

sch

edul

es.

Implement MeHg controls in the Delta & upstream watersheds

Continue to implement legacy Hg projects

Long-term offset projects

~2017

TMDLReview

Slide 19

OutlineDescription of the Delta Mercury ImpairmentOverview of the Proposed

Delta Program

Comparison to RMP Mercury Strategy’s Comparison to RMP Mercury Strategy’s High Priority QuestionsHigh Priority Questions

Questions & Discussion

Slide 20

RMP Priority Questions

1. Where and when does mercury enter the food web?

We have a general idea of the “where” in the main channels

Slide 21

CalFed Mercury ProgramFish Sampling

Average Hg Concentrations in largemouth bass, 2000

(Davis et al., 2003)

Inland silverside Hg & MeHg Concentrations, Fall 1999

(Slotton et al., 2002)

Lower fish Hgin Central Deltaduring relativelylow-flow years

Lower fish Hgin Central Deltaduring relativelylow-flow years

Elevatedfish Hgin Delta

periphery

Slide 22

RMP Priority Questions1. 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

Slide 23

RMP Priority Questions2. 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

Slide 24

RMP Priority Questions2. 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

Slide 25

Seven Control

Programsin One…

…because different areas of the Deltaare dominated by

different MeHg & TotHg

sources

Yol

o B

ypas

s

Southern

Delta

Slide 26

RMP Priority Questions2. Which processes, sources, & pathways

contribute disproportionately to food-web accumulation?

Need to refine load estimates for wetlands in the Delta & upstream watersheds

Slide 27

RMP Priority Questions3. What are the best opportunities for

management intervention for the most important pollutant sources, pathways & processes?

4. 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

Slide 28

RMP Priority QuestionsQuestions 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

Slide 29

RMP Priority QuestionsQuestions 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

Slide 30

RMP Priority QuestionsQuestions 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

Slide 31

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

San Joaquin River @ Vernalis

0

50

100

150

200

250

300

Sil

vers

ide M

eH

g (

mg

/kg

)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Wate

r M

eH

g (

ng

/l)

Silverside fish

water

Slide 32

RMP Priority QuestionsQuestions 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

2) Local bioaccumulation study: WWTP effluent contributes about the same amount of mercury to Sacramento River bioaccumulation as expected from its effluent methylmercury loads

Slide 33

RMP Priority QuestionsQuestions 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]

Slide 34

RMP Priority Questions5. 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?

Slide 35

Questions & Comments

Updates, reports & comments:

http://www.waterboards.ca.gov/centralvalley/

water_issues/tmdl/central_valley_projects/delta_hg/

Slide 36

Slide 37