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Development of a Site-Specific Standard for Selenium in Open Waters of Great Salt Lake, Utah. Central 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 - PowerPoint PPT Presentation
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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
What effects are of most concern?What effects are of most concern?
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
What effects are of most concern?What effects are of most concern?
• 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
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
Great Salt Lake StudiesGreat Salt Lake Studies
• 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
Key ObservationsKey Observations
– 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.
Key ObservationsKey Observations
• 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
Key ObservationsKey Observations
• 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.
RecommendationsRecommendations
3. For implementation, the water column concentration of selenium associated with the standard will be derived from the Bioaccumulation Model.
RecommendationsRecommendations
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
RecommendationsRecommendations
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
RecommendationsRecommendations
• 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?