The Environmental Protection Agency issued a memo this week saying contamination in groundwater that feeds into rivers, streams, and lakes doesnt need to be regulated under the Clean Water Act.

Indiana Department of Environmental Management sent letters to utilities in December noting that it can't give approval until utilities show how the plans will control contamination.

The Hoosier Environmental Council and five other groups are suing the U.S. Environmental Protection Agency over recent rollbacks to coal ash regulations.

The Main Ash Pond, owned by Tanners Creek Development LLC, is a "legacy pond" - which means it's located at a closed down power plant.

The proposed revisions include allowing individual states to set their own standards for coal ash disposal.

Duke Energy says the move is an attempt to use "fear and the courts to upend public policy."

State environmental officials must approve Duke's disposal plans, which include testing the site's groundwater monitoring wells at least twice a year.

The company plans to cap storage basins in Cayuga, New Albany, Owensville and Terre Haute, Indiana.

As Indiana environmental regulators grapple with how to deal with the storage of coal ash at power generating stations, environmental groups push for tough standards.

A group of environmental and health advocates are especially concerned about Indiana's coal ash ponds and protecting federal legislation to clean them up.