Biogeochemical Cycling of Selenium and Mercury in Bighorn Lake, Bighorn Canyon National Recreation Area, MT and WY

Funding provided by: US Geological Survey and National Park Service

D. Naftz and E. Barnhart, USGS, Helena, MT; D. Krabbenhoft and S. Janssen, USGS,Middleton, WI; C. Eagles-Smith, USGS, Corvallis, OR; C. Stricker, USGS, Lakewood, CO;T. Schmidt, USGS, Ft. Collins, CO; M. Ruggles, MT FWP, Billings, MT

♦ Elevated Hg levels in fish tissue relative to other National Parks

♦ Potential for geogenic sources of Hg (Yellowstone National Park)

♦ Sediment mitigation actions possible in future

♦ Selenium inputs to reservoir via WY landscapes

♦ Evolving information on Hg cycling in western reservoirs

♦ New EPA chronic selenium criteria approved in late 2016

PROBLEM

♦ Limnological and riverine controls on [Hg] and [Se]♦Hg and Hgisotopes in fish tissue♦Microbial community dynamics and Hg methylation♦Se and C / N isotopes in fish tissue♦Se sources to Bighorn Lake♦Comparison to other reservoirs♦Next steps

OUTLINE

BACKGROUNDHg methylation

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

BACKGROUNDBighorn Lake Hg advisories

USEPA – 0.3 mg/kg (ww)FDA – 1.0 mg/kg (ww) – “do not eat”

BACKGROUNDNew EPA 2016 Selenium Criteria

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

BACKGROUNDWY selenium issues

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

LIMNOLOGYSalinity gradients

♦ 2015 freshet replaced by higher salinity plume

♦ 2016 has higher salinity

♦ Freshwater lens below higher salinity layer

Early July Late August

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

LIMNOLOGYDissolved O2 gradients

♦ 2015 no inverted density gradient

♦ 2016 inverted density gradient associated with low DO areas

♦ Settling POMaccumulating on top of lower density freshwater lense

Early July Late August

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

LIMNOLOGYpH gradients

♦ Low pH values in 2015 likely degradation of POM on higher salinity layer (40 m)

♦ Low pH values during 2016 support areas of POMdegradation

Early July Late August

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

LIMNOLOGYDO gradients in side canyons

♦ Restricted circulationin side canyons

♦ Elevated levels ofMeHg in side canyonsediment

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

2015 2016

0.1

0.4

1.8

7.7

32.5

138.0

Turb., in NTU

0.1

0.4

1.8

7.7

32.5

138.0

Turb., in NTU

LIMNOLOGYTurbidity and THgsuspended

DISTANCE FROM YELLOWTAIL DAM, IN KM

Early July Late August

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

♦ Higher THgsuspendedduring July synoptic

♦ Turbidity and THgsuspendedgenerally agree during both synoptics

♦ Delivery of elevated THgsuspended to forebay

400 500 600 700 800 900

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

SPECIFIC CONDUCTANCE, IN µS/CM

DIS

SO

LVE

D S

ELE

NIU

M, I

N µ

G/L

AfterbaySide channelUpper reservoir

LIMNOLOGYSC and Se gradients

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

♦ Increasing Hg with increasing length (common)

♦ Numerous samples exceed FDA “do not eat” advisory

♦ Anomalous fish concentrations in upper reservoir sites?

♦ Tailwater fishery shows lowest mercury concentrations

MERCURY IN FISH TISSUE

Upper reservoir anomaly

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

♦ 199Hg = 199Hg(permil) / 198Hg(permil)

♦ Low 199Hg in tailwaterfishery reflects less photochemical processing of the Hg

♦ Water released from Yellowtail dam (> 50 m in depth) less opportunity for photochemical processing

199Hg IN FISH TISSUE

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

SRBs in Sediment SamplesDO gradients in side canyons

♦ Known Hg Methylators

♦ Elevated levels of MeHg in side canyon sediment

0

5000

10000

15000

20000

25000

1 2 5 8 10 13 15

15_r

eplic

ate 18 19

dsrB

cop

ies /

0.5

g s

edim

ent

Sulfate Reducing Bacteria

1000000

10000000

100000000

1E+09

11_

repl

icat

e 2 5 8 10 13 15 18 19

Bact

eria

l cop

ies /

0.5

g so

il

Total Bactera in Sediment

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

SRBs in Water SamplesDO gradients in side canyons

♦ Known Hg Methylators

♦ Elevated levels of MeHg in side canyon sediment

1

10

100

1000

10000

1 2M

2 11

3M 2 2M

5 20

M5

60M

5 2M

8 60

M8

2M10

50M

10 2

M13

12M

15A

2M18

32M

18 2

M19

51M

19 2

M

Bact

eria

l cop

ies /

mL

of w

ater

Total Bacteria in Water

0

5

10

15

20

25

30

35

1 2M

2 11

3M 2 2M

5 20

M5

60M

5 2M

8 60

M8

2M10

50M

10 2

M13

12M

15A

2M18

32M

18 2

M19

51M

19 2

M

dsrB

cop

ies /

mL

of w

ater

Sulfate Reducing Bacteria

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

• All sediment sites amplified

• Only 18B from the water samples amplified

-con 13 19 18 15 10 8 5 2 1

-con 13T 2B 8B 1B 5M 5B 15A 13 8T 5T 10B 5M

-con 18BR 18T 5M 15T 1T 19T 19B 18T 18B 10T 2T

Newly Identified Mercury Methylation GenesSediment Water Samples

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

FISH TISSUE SELENIUMTailwater fishery is anomalous

♦ Higher [Se] at depth in reservoir is reflected in tailwater fishery

♦ Some tissue samples in tailwater exceed/approach 2016 EPA chronic criteria of 11.3 mg/kg (dw)

♦ High Kds in dam release may influence Se uptake in lower trophic levels and smaller fish in tailwater?

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

FISH TISSUE C and N ISOTOPESYou are what you eat

♦ Tailwater brown trout are a full trophic level lower than reservoir population

♦ Is the tailwater food web influenced by organic detritus released from the reservoir chemocline?

♦ Is the high insect biomass in the tailwater influenced by selenium- and organic-rich detritus from the reservoir?

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

Se INPUTSBighorn vs. Shoshone Rivers

~ 3,420 kg Se/yr

~ 783 kg Se/yr

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

Oct Jan Apr Jul Oct Jan Apr Jul100

1,000

10,000

WY 2015 WY 2016

ME

AN

DA

ILY

DIS

CH

AR

GE

, IN

FT3 /S

EC

Lentic Se standard

Bighorn River at Kane, WY

Oct Jan Apr Jul Oct Jan Apr Jul0

0

0

WY 2015 WY 2016

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

DIS

SO

LVE

D S

ELE

NIU

M C

ON

CE

N-

TRA

TIO

N, I

N µ

G/L

Lentic Se standard

Shoshone River nr Lovell, WY

Bighorn River Shoshone River

Se INPUTSAreas susceptible to Se contamination

300 2

l., ate r

ileeSBighorn Lake

“Areas susceptible to irrigation-induced Se contamination of water and biota”

“Area where some bird eggs contain embryotoxicconcentrations of selenium”

“Area or site where surface water is selenium contaminated”

MTWY

0 50 km

Bighorn Rivergage

Shoshone River gage

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

Lake Koocanusa(Elk River only)

Bighorn Lake(Bighorn River only)

Se INPUTSComparison to Lake Koocanusa

♦ Lake Koocanusa volume = 7 km3

♦ Bighorn Lake volume = 1.7 km3

♦ Elk River = High Se and minor flow contributor

♦ Bighorn River = High Se and major flow contributor

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

N = 87 N = 50

0

2,000

4,000

6,000

8,000

10,000

12,000

ME

AN

AN

NU

AL

DIS

CH

AR

GE

, IN

CFS

0

2,000

4,000

6,000

8,000

10,000

12,000

ME

AN

AN

NU

AL

DIS

CH

AR

GE

, IN

CFS

N = 22 N = 21

0.37 INFLOW RATIOSLake Koocanusa and Bighorn Lake

Elk:Kootenay Bighorn: Shoshone2.42

Elk / Kootenay Bighorn / Shoshone

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

0.0

0.5

1.0

1.5

Bighorn Lake2015-16

Lake Koocanusa2015-16

N = 33

N = 56

2.0

G/L

µ N I,e

SD

EVL

OS

SID

INDIVIDUAL SAMPLES

Se IN WATERComparison to Lake Koocanusa

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

0

5

10

15

20

25

Se IN FISH TISSUEComparison to Lake Koocanusa

Lake Koocanusa (MT FWP) Bighorn Lake and tailwater (USGS / MT FWP)

Saug

er--

Rese

rvoi

r

rain

bow

trou

t --R

eser

voir

brow

n tr

out -

-Res

ervo

ir

Wal

leye

--Re

serv

oir

)YLE

ON

LCS

UM(

DWPP

M

, I

NeS

HISF

SPECIES

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

brow

n tr

out -

-Tai

lwat

er

rain

bow

trou

t --T

ailw

ater

LAKE POWELL COMPARISONSimilar reservoir morphology

Bighorn Lake, MT/WY

Lake Powell, AZ/UT

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

DISTANCE FROM YELLOWTAIL DAM, IN KM DISTANCE FROM GLEN CANYON DAM, IN KM

SIDE CANYON ANOXIABighorn Lake DO/Hg Lake Powell DO Lake Powell MeHg

LAKE KOOCANUSA BIGHORN LAKE♦ Se sourced from British

Columbia

♦ Two major river inflows (high Se + low flow)

♦ Modeled Se loads up to 13,000 kg/yr

♦ [Se] in reservoir ranges from 0.7 to 1.2 µg/L

♦ Listed under Section 303 (d) as threatened by Se

♦ Se sourced from Wyoming

♦ Two major river inflows (hiselenium + high flow)

Estimated Se loads ~ 4,20kg/yr

[Se] in reservoir ranges fro0.25 to 1.9 µg/L

No 303 (d) listing for Se

Tailwater impacts?

gh

♦ 0

♦ m

♦♦

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

LAKE POWELL BIGHORN LAKE♦ Long, narrow reservoir with

numerous side canyons

♦ Low levels of Hgwater in main channel

♦ Seasonal anoxia in narrow side canyons

♦ Elevated levels of MeHgwater in side canyons

♦ Hg fish advisory for lower reservoir

♦ Long, narrow reservoir with some side canyons

♦ Low levels of Hgwater in main channel

♦ Seasonal anoxia in side canyons

♦ Higher proportion of MeHgsediment and SRBsediment in side canyons

♦ Hg fish advisory for entire reservoir

Limnology [Hg]fish [Se]fish Se sources Other reservoirs

Se CONCEPTUAL MODEL

0.1

0.4

1.8

7.7

32.5

138.0

Turbidity

Kdand TTFs

Watershed inputs Reservoir transformations Afterbay TailwaterBighorn R.

Greybull R.

Shoshone R.Kdand TTFs

Kdand TTFsSe

sources and load reduction potential

BIGHORN LAKE FUTURE NEEDSSPARROW model (Preston et al., 2009) for Bighorn, Greybull, and Shoshone watersheds

Ecosystem-scale model (Presser and Luoma, 2010) for Bighorn Lake

Bighorn Lake Study Team

MANAGEMENT OPTIONSThermocline manipulation in side canyons

♦ Oxygenate bottom water and near-surface sediments

♦ Photodegrade MeHg?Solar pump operating at Newcastle Reservoir, Utah

SUMMARY♦ Low DO in side canyons and microbial populations

support Hg methylation

♦High Hg levels in larger reservoir fish

♦Elevated Se levels in reservoir water and tailwater fish tissue

♦Se loads to BICA from Bighorn River watershed

♦Similar Hg processes in Bighorn Lake and Lake Powell

♦Se model for BICA would be useful as an adaptive management tool