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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%