1

Methylmercury TMDL & Implementation Plan for the

Sacramento-San Joaquin RiverDelta Estuary

2006 National Monitoring Conference

Michelle Wood

2

Outline

TMDL Primer Why a MeHg TMDL? The Delta MeHg TMDL

3

Federal Clean Water Act

Section 303(d)Requires Total Maximum Daily Loads for waterways that don’t meet WQ standards even after

controlling point sources

4

Definition of TMDL:

The amount of a pollutant that a water body can receive and still

meet water quality standards (assimilative capacity)

5

TMDL Elements

Problem statement Numeric target Source analysis Linkage analysis Allocations

6

A TMDLWithout Implementation:

Ghost Regulation State Porter-Cologne Water

Quality Control Act Requires Regional Boards to

implement TMDLs TMDL implementation plans are

amended into State water quality plans (“Basin Plans”)

7

Central Valley

Mercury TMDLs

Delta

Clear Lake

Cache Creek Bear Creek

Harley GulchPutah Creek

American R.

Feather R.

SacramentoRiver

San Joaquin R.

8

The Delta

R

S

F

>1100 mi waterwaysDrains ~1/3 of CA

Reg

ion

5

ReduceCentral Valley

Mercury Outflows by 110 Kg/yr110 Kg/yr

Sacramento

Tracy

StocktonAntioch

Brentwood

Reg

ion

2

San Francisco Bay

9

MethylmercuryMost toxic form of mercury (a potent

neurotoxicant)

Sulfate-reducing bacteria convert mercury to MeHg

>90% mercury in top trophic level fish is MeHg

Exposure to MeHg is through consumption of fish & shellfish

10

MeHg Bioaccumulates…

Delta Water : Largemouth Bass

1: 6,500,000

0.1 ng/l

1 mg/kg

11

Atmospheric dep.

Urban & WWTP

Geothermal springs & Naturally enriched soils

Urban & WWTP

Wetlands

Agricultural Lands /Delta Islands

12

Concerns about Focusing Control Program on Only Inorganic Hg

Millions of kilograms released to waterways by historic mining

Much remains in channels & may be untreatable

Necessitate reliance on natural erosion as a reduction strategy

May take centuries to wash the mercury from the waterways

13

Interrupt the Methylation Cycle

Identify sources of MeHg Reduce methylation, and/or Reduce mercury sources that supply the

methylation sources

Shorten time to see fish tissue improvements from centuries to decades

14

Outline

TMDL Primer Why a MeHg TMDL?

The Delta MeHg TMDL

15

MeHg TMDL Elements Numeric target (a.k.a. WQO) Source analysis Linkage analysis Implementation plan with

Allocations Monitoring and evaluation

16

Numeric Target

Protect humans and wildlife

Main factor: fish consumption rates

There are many options…

17

Alternative Targets for Human ProtectionObjective

(catfish & bass, mg/kg)

Safe Consumption Amounts for Humans& Implications

0.58

• One 8 oz. meal every 2 weeks of a mixture of fish (USEPA default criterion of 0.3ppm)

• Does not protect fish-eating wildlife• Delta anglers eat mostly catfish & bass

0.24• One 8 oz. meal of a mixture of fish every week• Protects fish-eating wildlife & sport anglers

0.16 • One 8 oz. meal of bass/catfish per week

0.05

• FourFour 8 oz. meals every week of bass/catfish• Protects anglers who catch local fish as primary

source of protein

18

Wildlife Targets

Food Group / Species

TLFG Target

Large TL4 Goal

TL4 Fish (150-500 mm)Bald eagle 0.31 0.31

TL3 Fish (150-500 mm)Bald eagle 0.11 0.35

TL4 Fish (150-350 mm)Osprey 0.26 0.33

River otter 0.36 0.45TL3 Fish (150-350 mm)

Western grebe 0.08 0.29Common merganser 0.09 0.34

Osprey 0.09 0.34TL3 Fish (50-150 mm)

Kingfisher 0.05 0.63Mink 0.08 0.91

River otter 0.04 0.50Double-crested cormorant 0.09 0.98

TL3 (<50 mm)California least tern 0.03 0.36

Western snowy plover 0.10 1.20

LargeTL4 Fish

0.29

19

Large TL4 Fish: 0.24 ppm Humans: 1 meal/week of mixed bag Protects piscivorous wildlife species

Small TL3 Fish: 0.03 ppm Protects wildlife consuming small fish

where there are no big fish to monitor

Recommended Targets

Key Policy Question

20

MeHg Linkage

Links targets to sources using the Delta-specific mathematical relationship between water and fish MeHg concentrations

Determines a MeHg goal for ambient water

21

MeHg Sampling Locations

Used in Linkage

TL4 Fish – LMB –

Water –

22

Weighted Average

MeHg Levels in TL4 Fish

(mg/kg)

23

Large-mouthBass

Lengthvs.

MeHgConc.

Central Delta (Mildred Island)

y = 1E-05x1.68

R2 = 0.6405

0.0

0.5

1.0

1.5

0 100 200 300 400 500 600Length (mm)

Mer

cury

Con

cent

ratio

n (m

g/kg

)

0.19

Mokelumne River (Interstate 5)

y = 7E-07x2.4267

R2 = 0.8704

0.0

0.5

1.0

1.5

0 100 200 300 400 500 600Length (mm)

Mer

cury

Con

cent

ratio

n (m

g/kg

) 1.04

Sacramento River (RM44/Isleton)

y = 1E-08x3.0891

R2 = 0.7791

0.0

0.5

1.0

1.5

0 100 200 300 400 500 600Length (mm)

Mer

cury

Con

cent

ratio

n (m

g/kg

)

0.72

San Joaquin River (Vernalis)

y = 5E-06x2.0184

R2 = 0.6935

0.0

0.5

1.0

1.5

0 100 200 300 400 500 600Length (mm)

Mer

cury

Con

cent

ratio

n (m

g/kg

)

0.68

West Delta (Sherman Lake)

y = 0.0318e0.0065x

R2 = 0.6249

0.0

0.5

1.0

1.5

0 100 200 300 400 500 600Length (mm)

Mer

cury

Con

cent

ratio

n (m

g/kg

)

0.31

350 mm

0.191.04

0.72 0.68

0.31

Good methodfor evaluating

long-term changes!

24

Human Target [150-500 mm TL4 Fish]

y = 1.1725x

R2 = 0.9322

0.0

0.4

0.8

1.2

0.0 0.4 0.8 1.2TL Food Group MeHg Conc (mg/kg)

35

0-m

m L

MB

Me

Hg

Co

nc

(mg

/kg

)

0.24

0.28

TL4 Fish WQO & 350 mm LMB Hg Goal

Target forTL4 Fish

ImplementationGoal for LMB

25

y = 20.365x1.6374

R2 = 0.91

0.0

0.5

1.0

1.5

0.00 0.05 0.10 0.15 0.20

Unfiltered Aqueous MeHg (ng/l)

35

0-m

m L

MB

Me

Hg

(m

g/k

g)

0.28

0.073

350 mm LMB MeHg Goal & Average Annual Water MeHg Goal

ImplementationGoal for

Ambient Water:0.06 ng/l

as an annual average

26

RecommendedControl Program

1. Control MeHg sources

2. Control TotHg sources

3. Reduce MeHg exposure to the fish eating public

27

5-Year Study Period:

Conduct studies to characterize & control existing MeHg & Hg concentrations and loads

GOALS: Address uncertainty in load estimates

Develop technically & economically feasible controls

28

0

1

2

3

4

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65

Facilities

Me

Hg

Co

nc

. (n

g/l)

Preliminary Municipal WWTP MeHg Monitoring Results

26 < 0.05 ng/l

33 > 0.1 ng/l

29

Mercury Offset ProgramEnable beneficial projects

to proceed even ifon-site mercury controls

are not feasible

30

Timeline

Within 30 years: If implement MeHg controls, achieve measurable reductionsin fish tissue mercury

100+ years: Fully achieve WQO

31

Adaptive ImplementationAdaptive Implementation

ActionEvaluate

Monitor

Lower Fish MeHg

32

Next StepsReport for scientific peer review

Release draft BPA staff report

Board Hearing in Fall/Winter 2006

33

Acknowledgments

Data, Methods & Ideas

SFEI, UCDavis, SRWP, CMPSF Water Board staff, DHS, OEHHA, DFG,

Moss Landing Marine Laboratories, USGS, USFWS

***CALFED Mercury Program***

34

Questions & Discussion

35

36

Weighted Average

MeHg Levels in TL4 Fish

(mg/kg)0.26

0.57

0.920.56

37

Average Annual

Ambient MeHg Levels

in Water(ng/l)

0.05

0.3

0.15

38

Delta MeHg SourcesAverage Annual Loads

DeltaIslands

2%Urban0.42%

Open Water15%Tributary

Inputs63%

Within-Delta

Sources38%

WetlandHabitats

16%

Wastewater4%

Atmospheric Deposition

0.17%

39

San Joaquin Subregion Methylmercury Sources

Total Loading: ~478 g/yr

Tributaries77%

OtherInputs23%

Wastewater9%

Agri-culturalLands

5%

Wetlands4%

OpenWater

4% Urban1%

40

Yolo Bypass Subregion Methylmercury Sources

Total Loading: ~1,000 g/yr

AgriculturalLands

2%

OpenWater

8%

Other Inputs49%

Wetlands39%Tributaries

51%