The Tennessee Valley Authority discovered a leak Wednesday in a gypsum pond at its Kingston Fossil Plant, but TVA spokesman Barbara Martocci said the leak is mainly rainwater and does not pose any public safety risk.

"It's not supposed to be leaking, but at this point we don't know how big the leak is," Martocci said Wednesday night. "No gypsum has leaked out; it's simply a small water leak."

The Tennessee Department of Environment and Conservation, which regulates ash and gypsum ponds at coal plants, was notified around 6 p.m. Wednesday about the Kingston leak.

"We are investigating the leak, and obviously any unauthorized release is of concern to us and we will deal with it appropriately," TDEC spokeswoman Tisha Calabrese-Benton said.

TVA crews are trying to fix the leak. Emergency response agencies and local police were not immediately notified of the leak at Kingston, where a much larger coal ash leak nearly two years ago resulted in the worst environmental disaster in TVA history.

Three days before Christmas 2008, a coal ash pond at Kingston collapsed and spilled more than 5.4 million cubic yards of ash into the Emory River and related property. That spill damaged area homes and land. The cleanup is expected to cost TVA up to $1.2 billion.

Martocci said the latest leak was discovered at a pond built to contain gypsum residue from coal scrubbers that went online in June to help control smog emissions.

"The pond is relatively big, but the amount of gypsum in the pond is relatively small because we haven't been running the scrubbers very long," Martocci said.

TVA had a larger gypsum pond leak in January 2009 at its Widows Creek Fossil Plant, which resulted in a $25,000 civil penalty from the Alabama Department of Environmental Management for violating state and federal discharge rules.

In response to such problems in its ash and gypsum ponds, TVA plans to phase out wet storage of all coal ash and residues in the next decade.

Contact staff writer Dave Flessner at dflessner@times freepress.com or at 757-6340.