EDITOR'S NOTE:The baseline ecological risk assessment (BERA) of residual coal-fly ash in Watts Bar Reservoir was conducted following a 2008 spill from the Tennessee Valley Authority Kingston Fossil Plant (Roane County, TN). Results of the BERA were used to focus the long-term management strategy for the impacted river system. This article is among 7 peer-reviewed articles in the special series, "Ecological Risk Assessment for Residual Coal Fly Ash at Watts Bar Reservoir, Tennessee." The series includes articles presenting the following: problem formulation for the river system; sediment toxicity test procedures; benthic community analysis techniques; methods used to evaluate risks to benthic organisms, fish, and riparian and aquatic wildlife; an extensive analysis characterizing risk to insectivorous birds; and finally, how the BERA results influenced management decisions. ABSTRACTA baseline ecological risk assessment (BERA) was performed for residual ash in the Watts Bar Reservoir following a release of fly ash from the Tennessee Valley Authority (TVA) Kingston Fossil Plant. The site consists of parts of 3 rivers in eastern Tennessee comprising over 32 river kilometers. The purpose of the assessment was to determine if residual ash negatively impacts maintenance and reproduction of balanced communities or populations of potentially exposed ecological receptor groups in these rivers. This introductory article summarizes the site and environmental setting, assessment and measurement endpoints, risk characterization methods, and the study approach. Subsequent articles describe ecological risks to fish, benthic invertebrates, aquatic-and riparian-feeding wildlife, and aerial-feeding insectivores; and the role ecological risk characterization played in determining the most effective management of the residual ash, setting project remediation objectives and targets, and designing long-term monitoring to measure the effectiveness of the selected removal action. Integr Environ Assess Manag 2015;11:32-42. © 2014 SETAC

EDITOR'S NOTE:The Baseline Ecological Risk Assessment (BERA) of residual coal-fly ash in Watts Bar Reservoir was conducted following a 2008 spill from the Tennessee Valley Authority Kingston Fossil Plant (Roane County, Tennessee, USA). Results of the BERA were used to focus the long-term management strategy for the impacted river system. This paper is among 7 peer-reviewed papers in the special series, "Ecological Risk Assessment for Residual Coal Fly Ash at Watts Bar Reservoir, Tennessee." The series includes papers presenting the following: problem formulation for the river system; sediment toxicity test procedures; benthic community analysis techniques; methods used to evaluate risk to fish, and riparian and aquatic wildlife; an extensive analysis characterizing risk to the insectivorous tree swallow; and finally, how the BERA results influenced management decisions. ABSTRACTCurrent scientific advances in metal and metalloid risk assessment were applied to evaluate risk to aquatic and riparian wildlife species potentially impacted by residual coal fly ash after cleanup of an unprecedented large ash release into an aquatic environment-the first assessment of its kind. Risk was evaluated using multiple lines of evidence (LOE), including 1) tissue-based risk assessment of inorganic concentrations in piscivorous and insectivorous bird eggs and raccoon organs, 2) deterministic and probabilistic diet-based risk estimates for 10 receptors species, 3) raccoon health metrics, and 4) tree swallow nest productivity measures. Innovative approaches included use of tissue-based toxicity reference values (TRVs), adjustment of bioavailability in the dietary uptake models (using sequential metal extractions in sediment), partitioning chemical species into uptake compartments (e.g., prey gut, nongut, sediment), incorporating uncertainty in both modeled dose and dietary TRVs, matching TRVs to chemical forms of constituents, and pairing these LOEs with reproductive success or health status of sensitive receptor species. The weight of evidence revealed that risk to wildlife from residual ash was low and that risk, though low, was most pronounced for insectivorous birds from exposure to Se and As. This information contributes to the debate surrounding coal combustion residue regulations prompted by this ash release. Because of the responsible party's proactive approach of applying state-of-the-art methods to assess risk using several LOEs that produced consistent results, and because of their inclusion of the regulating agencies in decisions at every step of the process, the risk assessment results were accepted, and an effective approach toward cleanup protective of the environment was quickly implemented. This study highlights the value of using multiple LOEs and the latest scientific advances to assist in timely decision making to obtain an effective remedy for an emergency spill. Integr Environ Assess Manag 2015;11:67-79. © 2014 SETAC

Coal‐fly ash was released in unprecedented amounts (4.1 × 106 m3) into the Emory River from the Tennessee Valley Authority Kingston Fossil Plant on Watts Bar Reservoir in Tennessee. Tree swallows were exposed to ash‐related constituents at the ash release via their diet of emergent aquatic insects, whose larval forms can accumulate constituents from submerged river sediments. Reproduction of tree swallow colonies was assessed over a 2‐year period by evaluating whether 1) ash constituent concentrations were elevated in egg, eggshell, and nestling tissues at colonies near ash‐impacted river reaches compared to reference colonies, 2) production of fledglings per nesting female was significantly lower in ash‐impacted colonies versus reference colonies, and 3) ash constituent concentrations or diet concentrations were correlated with nest productivity measures (clutch size, hatching success, and nestling survival, and fledglings produced per nest). Of the 26 ash constituents evaluated, 4 (Se, Sr, Cu, and Hg) were significantly elevated in tissues potentially from the ash, and 3 (Se, Sr, and Cu) in tissues or in swallow diet items were weakly correlated to at least one nest‐productivity measure or egg weight. Tree swallow hatching success was significantly reduced by 12%, but fledgling production per nest was unaffected due to larger clutch sizes in the impacted than reference colonies. Bioconcentration from the ash to insects in the diet to tree swallow eggs appears to be low. Overall, adverse impacts of the ash on tree swallow reproduction were not observed, but monitoring is continuing to further ensure Se from the residual ash does not adversely affect tree swallow reproduction over time. Integr Environ Assess Manag 2015;11:56–66. © 2014 SETAC

The Tennessee Valley Authority conducted a Baseline Ecological Risk Assessment (BERA) for the Kingston Fossil Plant ash release site to evaluate potential effects of residual coal ash on biota in Watts Bar Reservoir, Tennessee. The BERA was in response to a release of 4.1 million m3 of coal ash on December 22, 2008. It used multiple lines of evidence to assess risks for 17 different ecological receptors to approximately 400 000 m3 of residual ash in the Emory and Clinch rivers. Here, we provide a brief overview of the BERA results and then focus on how the results were used to help shape risk management decisions. Those decisions included selecting monitored natural recovery for remediation of the residual ash in the Emory and Clinch rivers and designing a long‐term monitoring plan that includes adaptive management principles for timely adjustment to changing conditions. This study demonstrates the importance of site‐specific ecological data (e.g., tissue concentrations for food items, reproductive data, and population data) in complex ecological risk assessments. It also illustrates the value of the US Environmental Protection Agency's (USEPA) data quality objectives process in building consensus and identifying multiple uses of results. The relatively limited adverse effects of this likely worst‐case scenario for ash‐related exposures in a lotic environment provide important context for the USEPA's new coal combustion residue disposal rules. Integr Environ Assess Manag 2015;11:80–87. © 2014 SETAC

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