The Sierra Club, citing a study by Wake Forest biology research associate professor Dr Dennis Lemly, said the report indicated selenium pollution from coal ash waste pits at Duke Energy’s 575-megawatt Sutton power plant in Wilmington sparked mutations and death of several fish species.

The study analysed more than 1400 fish from Sutton Lake, uncovering several species of fish in the water body that had disturbing mutations of the head, mouth, spine or tail.

It said many of the fish had been dying before reaching maturity.

Additionally, the group said, catchable bass levels at Sutton Lake had been cut in half since 2008, which has impacted the popular bass fishing economy.

The Sierra Club said the value of the lake’s lost natural resources was in the millions and the cost to replace lost fish was more than $US4.5 million ($A5 million) annually.

“If North Carolina replaced all fish killed by selenium pollution over the last 25 years, taxpayers would face a bill of more than $112 million,” it said.

“For subsistence and sport fishermen, the value of the lost fish exceeds $1.1 million per year and more than $28 million for a 25-year period.”

Sierra Club Beyond Coal campaign official Kelly Martin called the findings “shocking”

“We know coal ash pollution harms people, wildlife and our treasured natural places,” she said.

“Duke Energy needs to stop stalling and take responsibility for its ongoing violations.”

The group noted that the North Carolina Department of Environment and Natural Resources and Duke Energy both had knowledge of the contamination for years but nothing had been done to stop the leaks.

The Southern Environmental Law Center sent the North Carolina Department of Natural Resources and Duke Energy notice of its intent to file suit to clean up Sutton’s pollution and DENR in response filed a state court enforcement action.

The state court has permitted the SELC to intervene in the action on behalf of fellow environmentalists Cape Fear Riverwatch, the Sierra Club and Waterkeeper Alliance.

The conservation groups have also filed suit in federal court to require clean-up of the coal ash pollution under the federal Clean Water Act.

Sierra Club noted that Duke Energy’s plan was to stop burning coal at Sutton next year.

However, it said, selenium contamination harm could continue for a long time to come.

Duke officials have not released a public comment on the group’s latest claims.