Pollution from coal ash at a Duke Energy power plant in Wilmington kills hundreds of thousands of young fish a year and deforms many more, says a study commissioned by environmental groups that are suing Duke.
Duke called the findings “highly suspect,” saying its own studies over more than 30 years have found no health effects on fish.
Dennis Lemly, a research biologist at Wake Forest University who authored the environmental study, calculates that selenium from Duke’s ash kills 900,000 fish a year in Sutton Lake. The popular fishing lake cools water from Duke’s Sutton coal-fired power plant.
Duke retired the plant’s coal-burning units in November, but environmental advocates want Duke to remove the ash in two ponds at Sutton.
Selenium is a naturally occurring element that is found in coal ash, which is stored in ponds at Sutton that drain to the lake. Eating too much selenium in food can cause health problems in people, such as brittle hair and deformed nails, but it can also cause deformities in young fish.
Selenium in a lake at another Duke power plant, Belews Creek in Stokes County, wiped out 19 of the lake’s 20 fish species in the 1970s. Fish have largely recovered since then.
State wildlife officials have expressed concern over selenium in Sutton Lake in recent years, according to emails and presentations.
Lemly reported that 29 percent of the 529 small bluegill and similar fish he studied were deformed. Because fish with disfigured mouths, fins or tails presumably die young, he estimated that selenium kills 20 to 30 percent of the lake’s bluegills each year.
Recent swings in numbers of largemouth bass, a popular sport fish, have also been reported at Lake Sutton. Lemly’s study found few small bass to analyze.
“It’s reasonable to assume the largemouth bass are experiencing approximately the same level of mortality as the bluegills,” he said. The species share similar sensitivities to selenium, he said.
State data show toxic levels of selenium in bluegill and bass since 1987, he said.
Duke acknowledged elevated levels of selenium in Sutton Lake, compared with nearby rivers but said they reflect the lake’s function as a cooling pond and wastewater treatment system.
Duke said its sampling of hundreds of thousands of fish at Sutton over 36 years has shown no ill effects. Catch rates, reproduction and weights show a “thriving fish population” in the lake, Duke said in a statement.
“Catch rates per hour in the lake are very positive for largemouth bass and other species, and a widespread mortality as alleged in the report would not support that reality,” the company said.
Duke questioned Lemly’s conclusion that deformed fish die while young, saying if that were so it would not have been possible for him to find specimens to analyze.
Lemly’s study was commissioned by the Southern Environmental Law Center, which represents the Waterkeeper Alliance, the Sierra Club and Cape Fear River Watch. The groups have joined a state lawsuit against Duke over coal ash and have filed a separate federal suit over ash pollution.
State catch tests of largemouth bass in Sutton Lake indicated that numbers fell by about half between 2008 and 2010 but have since rebounded somewhat, said Christian Waters, fisheries program manager for the N.C. Wildlife Resources Commission.
The lake’s bass numbers have cycled up and down for years, he said. Selenium is among the factors that could account for that, he said, as well as other factors such as the presence of aquatic plants, which provide cover for bass, and flathead catfish that eat bass.
“Through (scientific) literature we know selenium can have impacts on reproduction,” Waters said. “We know it’s present in the lake, we know it’s present in fish at different levels, and we know it could make a difference.”
Waters said he’s not aware of reports of deformed fish in the lake.
Concentrations of selenium in Sutton Lake itself are within the federal standard, Lemly said, suggesting the standard is too high. The Environmental Protection Agency last reviewed the standard about a decade ago, he said, but has not changed it.
Lemly estimated it will take 46 years for selenium levels in Sutton Lake to reach harmless levels once Duke’s ash-pond discharges stop.
Henderson: 704-358-5051; Twitter: @bhender
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