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Reservoir Management Strategies to Reduce Fish Mercury Levels
California Statewide Mercury Control Program for Reservoirs
NALMS Symposium Nov. 1, 2013
Multi-Region Team Carrie Austin , Stephen Louie,
Michelle Wood, & many others •1
California Statewide Mercury Control Program for Reservoirs
Goal: Quickly, measurably reduce fish MeHg
•2
Website with fact sheets & updates www.waterboards.ca.gov/water_issues/programs/mercury
•See Fact Sheet:
Outline
•3
Outline
•4
Methylmercury Production
Outline
•5
Multiple factors
Food Web Transfer
Methylmercury Production
Limited benefits from source control
•6
Limited benefits from source control
•7
low sedHg, high fish MeHg
Manage redox conditions
Redox sequence:
O2 aerobic heterotrophs NO3
- denitrifiers MnO2(s) fermenters Fe(OH3)(s) fermenters SO4
2- sulfate reducers H+ methane producers
• Avoid
•Desirable
•8
Methylmercury Production
Oxygenation: Session F2 Mercury Management 1
Hypolimnetic Oxygenation to Reduce Bioavailable Mercury in Santa Clara Valley Water Supply Reservoirs
The Effect of Oxygen, Nitrate and Aluminum Hydroxide on Methylmercury Efflux from Contaminated Profundal Lake Sediments
Efficacy of Hypolimnetic Oxygenation on Managing the Accumulation of Mercury in Lakes
Monitoring Effects of Hypolimnetic Oxygenation on Methyl Mercury in Fish in Water Supply Reservoirs
•9
Oxygenation Pilot Tests
Santa Clara Valley Water District • Solar-powered circulators • HOS line diffuser
•10
Solar-powered circulator MeHg
•Annual coincidence: MeHg & seasonal anoxia
•11
•Citation: Santa Clara Valley Water District
Citation: Dave Drury SCVWD
Santa Clara Valley Water District
•12
•HOS: •Hypolimnetic Oxygenation System
Full-scale oxygenation
Calaveras Reservoir
•13
Camanche Reservoir
Speece cone 2 mile DO plume
Bonus Methylmercury
Production
Effect of HOS on fish mercury
Manage redox conditions
Redox sequence:
O2 aerobic heterotrophs NO3
- denitrifiers MnO2(s) fermenters Fe(OH3)(s) fermenters SO4
2- sulfate reducers H+ methane producers
• Avoid
•Desirable
•14
Methylmercury Production
15
Source Removal and Nitrate Addition Onondaga Lake, New York
Citation: Charles T. Driscoll Syracuse University
•16
•16
16
Citation: Charles T. Driscoll Syracuse University
17
Citation: Charles T. Driscoll Syracuse University
0 1 2 3
Dep
th (m
)
10
12
14
16
18
20072008200920102011
MeHg (ng L-1)
0 1 2 3 0 1 2 3 4
August September October
18
Citation: Charles T. Driscoll Syracuse University
0 1 2 3
Dep
th (m
)
10
12
14
16
18
20072008200920102011
MeHg (ng L-1)
0 1 2 3 0 1 2 3 4
August September October
19
Citation: Charles T. Driscoll Syracuse University
Manage fishery
•20
Food lower in MeHg
Cull fish
Select species
Food Web Transfer
Food lower in MeHg
•21
Fertilize ↑ Algae = MeHg
No more than 2x Chl-a and Chl-a ≤5 ug/L
1
•Algal Bloom Dilution
Food lower in MeHg
•22
Fertilize ↑ Algae = MeHg
1
Stock prey with low MeHg e.g., Rainbow trout
2
•Citation: Jesse Lepak
Cull or “intensive fishing”
•23
Select species
•24
Stock – hatchery diets low in MeHg
0
0.1
0.2
0.3
Stocked Resident
Rainbow trout
Citation: Mike Horvath, SFPUC
Select species
•25
0
0.5
1
1.5
200 600 1,000
Hg (m
g/kg
)
Length (mm) Land-Locked Anadromous
Chinook
Stock – hatchery diets low in MeHg
0
0.1
0.2
0.3
Stocked Resident
Rainbow trout
Restore native anadromous fish
Citation: Mike Horvath, SFPUC
California Statewide Mercury Control Program for Reservoirs
•26
Source control manage expectations Pilot tests
Website with fact sheets & updates www.waterboards.ca.gov/water_issues/programs/mercury
Multiple factors
•27
Upland and in-lake remediation areas
Isolation cap 172 ha
Thin layer cap 11ha
Groundwater barrier wall
Extensive remediation at former factory sites
Citation: Charles T. Driscoll Syracuse University
28
↓ Hg → reservoir (source control)
•29
Atmospheric Deposition
Mines mercury and gold
•30
Mercury from atmospheric deposition and mines
Reservoirs with no record of upstream gold or mercury mines;
60 have fish MeHg > target
At least 1 recorded upstream gold or mercury mine
Can have high fish MeHg but low atm dep and no mines
Can have low fish MeHg but very high atm Hg dep
Very highest fish MeHg associated with extensive Hg mining
Multiple Factors
California: 350 reservoirs and lakes
•Average of highest trophic level
Multiple factors: fish species
0
10
20
30
40
50
60
70
80
90
100
0.001 0.01 0.1 1 10
% Rank
Average Fish MeHg Concentration (mg/kg)
Region 2Other Regions
Target 0.2 mg/kg
SF Bay Region: hotspot for
high fish mercury levels
•32
•Large dots: High prevalence of R2 reservoirs at
extreme of distribution