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 the question Understanding Se in Great Salt Lake Philosophical decision about protectiveness Steering Committee, Water Quality Board Research Program

Outline Research Program Overview –Preliminary steps –GSL Studies Observations Recommendations

Research 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? 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? 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? 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? 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 EC 10 as protective of beneficial uses

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.

Great 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 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 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 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 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

Projects 2 & 5 Project 1 Mallard Toxicity Curve Bioaccumulation Model

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

Recommendations 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.

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

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

Recommendations 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

Recommendations Six Science Panel members recommended mg/kg, the mean EC 10 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

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