development of a site-specific standard for selenium in open waters of great salt lake, utah

Development of a Site-Specific Standard for

Selenium in Open Waters of Great Salt Lake, Utah

Development of a Site-Specific Standard for

Selenium in Open Waters of Great Salt Lake, Utah

Central QuestionCentral Question

What is the acceptable waterborne concentration of selenium (Se) that prevents impairment of the beneficial uses of the open waters of the Great Salt Lake?– Two parts to answering

the question• Understanding Se in Great Salt Lake • Philosophical decision about protectiveness

Steering Committee,

Water Quality Board

Research Program

OutlineOutline

• Research Program Overview– Preliminary steps– GSL Studies

• Observations

• Recommendations

Research Program OverviewResearch Program Overview

• Began with formation of the Science Panel in 2004

• Science Panel initially commissioned two studies– Development of analytical

techniques– Conceptual model of Se

cycling in GSL

What effects are of most concern?What effects are of most concern?

• Panel agreed that birds were likely the beneficial users of Great Salt Lake that are most sensitive to Se

• Exposure of birds to Se is through their diet

• Water quality standard will be developed to be protective of birds that feed primarily on open waters of Great Salt Lake

Study Area:Open waters of GSL


Best-documented and most readily monitored effect of Se on birds is reproductive success. More

information is required to understand effect of Se on body weight/condition of migrating or over-wintering birds.

Body Weight/Condition(Eared Grebes, Common

Goldeneyes)

Reproductive Success(California Gulls, American

Avocets, Black-Necked Stilts)

Critical Endpoints


• How is reproductive success defined?– Practically measured by egg

hatchability

– Hatchability (or hatching

success) is the percentage of eggs

that hatch from those that are incubated full term

– Hatchability is a more sensitive endpoint than teratogenesis endpoint (deformities)

How much Se in eggs is too much?How much Se in eggs is too much?

• Subject of debate for many years• Science Panel members submitted all

information they deemed pertinent to answering this question– 29+ publications– offered their own opinions

• Science Panel, by consensus, identified the analysis in Ohlendorf 2003 as the analysis to be used, and the range defined by its EC10 as protective of beneficial uses

How much Se in eggs is too much?How much Se in eggs is too much?

• The range of values that will prevent impairment of beneficial uses on GSL was determined to be:– 6.4 – 16 mg Se/kg– each value within this range has

its own estimated level of effect ranging from 2 – 21% reduction in hatchability

• Range is based upon mallard

studies to incorporate “safety factor”• Since November 2006, new analyses have been discussed.

Each discussion resulted in confirmation of the initial range of values.

S elenium- I nduced T erat ogenesis in N at ureLo g istic Re sp o nse C urve s

Egg S elenium Concent r at ion (mg/ kg, dr y wgt . )

Prob

abili

ty o

f T

erat

ogen

ic E

mbr

yo

0 20 40 60 80 100 120

0.0

0 .2

0 .4

0 .6

0 .8

1 .0

D U C KN =19 7

STILTN =93 1

AVOC ETN =86 8

Great Salt Lake StudiesGreat Salt Lake Studies


• Project 1– Mike Conover, John Cavitt– Looked at breeding,

migrating and over-wintering birds

• Project 2 & 5– Wayne Wurtsbaugh, Brad

Marden, Martin Grosell– Looked at uptake from

water/sediment to brine shrimp and brine flies


• Project 3– Dave Naftz, Bill Johnson– Looked at sources of Se

to Great Salt Lake

• Project 4– Bill Johnson, Dave Naftz– Looked at Se cycling

and Se loss mechanisms

Key ObservationsKey Observations

• Question No. 1 – Any effects from Se observed?– Reproductive effects

• No egg hatchability effects or deformities were observed in eggs or chicks of gulls, avocets, or stilts associated with the open waters of Great Salt Lake.

• Hatching rates consistent with non-contaminated sites• Egg Se in gulls = 2.89 mg/kg & shorebirds = 2.72 mg/kg;

below the 85 percentile of background levels.• 3 eggs out of 133 eggs in lower half of Panel guidelines;

all from near KUCC outfall


– Non-reproductive effects• A determination cannot be made at this time

due to confounding variables and insufficient data; however, elevated concentrations of selenium and mercury were found in bird blood and livers. This may indicate that some of these birds are using selenium to detoxify mercury.


• Question Nos. 2 & 3 – How is Se taken up into the food chain?– Summarized in individual final reports– Data and observations integrated into a GSL-

specific Bioaccumulation Model

Pro

ject

s 2

& 5

Pro

ject

1

Mallard Toxicity Curve

Bioaccumulation Model


• Questions 4 & 5 – Where does Se come from and go?

27%

27%

25%

11%

8% 2%

Goggin Drain KUCC Outfall Bear River Farmington Bay Lee Creek Weber River

– Most Se went to atmosphere, followed by to the North Arm and sediment– Identified more Se loss from than loads to GSL–Observed Se in GSL increase slightly–Mass balance requires more research

Selenium Loads

RecommendationsRecommendations

1. The water quality standard should be a tissue-based standard, based upon the selenium concentration found in bird eggs.

2. A selenium water quality standard that prevents impairment for aquatic dependent wildlife of Great Salt Lake lies within the range of 6.4 to 16 mg Se/kg for bird eggs.


3. For implementation, the water column concentration of selenium associated with the standard will be derived from the Bioaccumulation Model.


4. The State should adopt a tiered approach for monitoring, assessment, and management options to ensure the selenium water quality standard is not exceeded.

Objective for Each LevelLevel 1Level 2

Level 3

Level 4

Sampling Programs:

Management Options

DefinitionsW1: Trigger 1 for water concentrationD1: Trigger 1 for diet concentrationE1: Trigger 1 for egg concentration

Trigger 3 represents the site-specific numeric water quality standard; this may be a water or tissue-based concentration.

Scenarios for ConsiderationScenario

No.

1

2

3

4

Note:

Develop and Implement a Se Monitoring Program for

Great Salt Lake

Continue Increased Sampling Locations & Frequency for Water &

Invertebrates

Implement Management Options

W1 < W < W2 or D1 < D < D2

W2 < W < W3, and/or D2 < D < D3 (but E < E2)

Continue Hatchability Studies to Verify Effect on Eggs

E2 < E < E3 and (W2 < W < W3, or D2 < D < D3)

E2 < E < E3 and W2 < W < W3, and D2 < D < D3

Great Salt Lake is listed on 303(d) list as impaired.

Initiate TMDL Studies

W > W3 and/or D > D3 but E < E3

E > E3

Evaluate Bioaccumulation Model and Triggers, Reduce Monitoring

Frequency if no Exceedence for 3 years

E1 < E < E2 and/or W1 < W < W2, and/or D1 < D < D2

Continue Sampling of Eggs

W1 < W < W2 and D1 < D < D2 (but E < E1)

Objectives: 1. Verify Increase Above Trigger 12. Investigate if Increase in Water & Diet is Reflected in Eggs

LEVEL 1

Tier 1

Tier 2

Continue Increased Locations & Frequency of Water/Invertebrates/Eggs

Sampling

Tier 1

Tier 2

W > W1 and/or D > D1

W < W1 and D < D1

Objective:1. Verify Increase Above Trigger 3

Objectives: 1. Verify Increase Above Trigger 22. Verify Increase in Egg Concentrations via Hatchability Study

Objective: 1. Determine the Concentration of Se in Water and Brine Shrimp

LEVEL 2

LEVEL 3

LEVEL 4

W > W2 and/or D > D2 and/or E > E2

W > W3 and/or D > D3 and/or E > E3

W > W1 and D > D1

E > E2 and W > W2

and/or D > D2


5. The State should conduct further research on a number of topics to validate and assess the current model and standard

6. Levels of protectiveness will be recommended by Steering Committee and determined by Water Quality Board

7. Individual position statements were prepared by each Science Panel member


• Six Science Panel members recommended 12-13 mg/kg, the mean EC10 for mallard eggs

• One member recommended 5.0 mg/kg

• One member abstained (USGS policy did not allow for recommendation)

• All recommended that assessment framework be included as part of standard

Questions/Comments?Questions/Comments?

development of a site-specific standard for selenium in open waters of great salt lake, utah

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