As usual, sedimentary deposits tell the tale:
"Our results clearly indicate the presence of coal ash at the bottom of Sutton Lake and suggest there have been multiple coal ash spills into the lake from adjacent coal ash storage facilities after, and even before, floodwaters from Hurricane Florence caused major flooding in 2018," said Avner Vengosh, professor of geochemistry and water quality at Duke University’s Nicholas School of the Environment, who led the research.
According to Vengosh and his colleagues from Duke and Appalachian State University, the amount of contaminants was more than what was found in streams following major coal ash spills in Kingston, Tennessee in 2008 and the Dan River in North Carolina in 2014.
Of course Duke Energy is spouting denials and rationalizations left and right, but Avner knows his stuff. This isn't an environmental advocacy org speaking, it's pure science:
To do the study, they conducted four independent sets of laboratory tests on bottom sediments collected in October 2018 from seven sites in Sutton Lake and three sites in the adjacent Cape Fear River. They also analyzed three sediment samples collected from Sutton Lake in 2015 and three more collected that same year from nearby Lake Waccamaw, which has never served as a coal ash impoundment.
The researchers analyzed each sample using four different methods for detecting and measuring the possible presence of coal ash solids -- magnetic susceptibility, visual observation of microscopic coal ash particles, trace element distributions, and strontium isotope ratios.
The tests revealed high levels of coal ash solids mixed with natural sediments in the samples collected from Sutton Lake in both 2018 and 2015.
Among the contaminants detected were many metals -- including arsenic, selenium and thalium, once used as rat poison -- that have toxic impacts at elevated levels. The metals are naturally found in coal and are enriched in coal-ash residuals when the coal is burned.
Past studies by Vengosh’s lab have shown that some of these metals, such as arsenic, can be released from coal ash solids into water trapped between grains of sediment at the lake’s bottom, where they build up and, over time, bioaccumulate up the local food web. A 2017 study by Duke University Ph.D. student Jessica Brandt revealed that 85% of all fish tissue samples collected from Sutton Lake still contained selenium at levels that exceeded Environmental Protection Agency standards four years after the coal-fired power plant there was retired. Another study showed that strontium isotope ratios in the inner ears of fish from Sutton Lake now mirror the ratios found in coal ash.
SELC tried to get a health advisory issued 5 years ago over Selenium detected by University of Florida researchers, but Duke Energy quashed that as soon as they got wind of it. As a result, people are still eating the fish not caught during the Wintertime.