(Adds details form company statement, share price)
Sept 21 (Reuters) - Duke Energy Corp said on Friday breaches in the cooling lake dam of its 625-megawatt natural gas L.V. Sutton plant in North Carolina due to flooding conditions in the Cape Fear river forced the utility to shut down the unit.
Water is now exiting the cooling lake through breaches, one large and several smaller, on the southern end of the impoundment, the company said.
Site personnel are supplementing on-site supplies with large stones and other materials, and engineering experts are moving to the site.
The company's shares were down 1.4 percent at $79.55 in afternoon trading.
The Associated Press had earlier reported on the dam breach.
Floodwaters had overtopped a steel retaining wall containing one of three large coal ash dumps lining the lakeshore, the company told the AP, adding that it cannot rule out that ash might be escaping and flowing into the Cape Fear river.
Duke reported two coal ash leaks from a retired plant in Wilmington, North Carolina, following storm Florence. One came from its shuttered Sutton Power Plant on Saturday and a second on Sunday, according to federal officials.
Coal ash can contaminate water and harm fish and wildlife. Ash pits and other embankments have ruptured under heavy rain in the past, and Duke Energy had agreed to secure the sites in North Carolina's lowland areas - but that work is ongoing.
In 2015, the company was fined more than $100 million after a 2014 spill that at the time was the third-worst coal ash spill in U.S. history. (Reporting by Ankur Banerjee in Bengaluru; Editing by Anil D'Silva and Shounak Dasgupta)