High levels of an element found in coal ash have been detected in fish in two lakes where Duke Energy coal-fired power plants are located, Duke University researchers reported Tuesday.
Fish in a third lake, Mountain Island near Charlotte, held selenium but at levels below a federal threshold set to protect aquatic life.
The element, selenium, occurs naturally but is concentrated in coal ash. Exposure to it can cause deformities, impaired growth and reproduction problems in fish, and can be toxic to birds that eat the fish.
The Duke researchers linked the selenium they found in the lakes to the reported discharges from coal ash ponds.
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“Across the board, we’re seeing elevated selenium levels in fish from lakes affected by coal combustion residual effluents,” said study leader Jessica Brandt, a graduate student in environmental health at Duke’s Nicholas School of the Environment.
Duke Energy said its biologists haven’t observed problems with fish in the lakes, and said it met the terms of its ash pond discharge permits.
The concentrations detected in the study aren’t likely to be health concerns for people who eat exposed fish, for whom it is an essential mineral.
The Duke University researchers measured selenium levels in surface water, bottom-sediment waters and fish from Sutton Lake near Wilmington, Mayo Lake near Roxboro, and Mountain Island Lake. For comparison, they also tested three lakes with no history of coal ash contamination.
Sutton Lake had the highest levels of selenium, with 85 percent of all fish muscle samples containing levels above a threshold set by the Environmental Protection Agency to protect aquatic life.
In Mayo Lake, 27 percent of muscle samples exceeded the EPA criteria. Levels were below the EPA criteria in Mountain Island Lake, which researchers noted has a faster flow to move contaminants downstream than the other two lakes.
Duke’s Sutton power plant and the Riverbend plant on Mountain Island Lake are retired and their ash ponds are being closed. The Mayo plant, which now holds ash in a landfill, will also close its old ash pond.
Duke Energy said it has not observed declining fish populations or health problems in fish at the Sutton and Mayo lakes. Both are popular with anglers.
“While we haven’t seen the study to be able to review their specific findings, fish populations are thriving in these reservoirs,” spokeswoman Erin Culbert said of the study.
The peer-reviewed study was published Monday in the journal Environmental Science & Technology. Primary funding came from the North Carolina Water Resources Research Institute, with additional support from the EPA, the National Institute of Environmental Health Science and the Foundation for the Carolinas.