The coalition, representing seven states, accuses the Environmental Protection Agency of failing to implement rules created after an ash pond collapse in Tennessee in 2008 sent a billion gallons of toxic sludge into a river.
The coalition, represented by the environmental law firm Earthjustice, said it would sue the EPA to force implementation of the rules that would label coal ash as hazardous or non-hazardous waste and establish safety requirements for ash ponds where waste from coal-fired power plants is held, USA Today reported Monday.
The coalition contains groups from Illinois, Kentucky, Maryland, Montana, Nevada, North Carolina and Tennessee.
An Earthjustice attorney alleged the delay was because of "intense pressure from the coal and power industries."
Opposition to the rules has come from businesses that recycle ash for use in a number of products.
A hazardous classification would increase the cost to transport the ash and could have an impact on jobs, said Scott Sutton, spokesman for Raleigh, N.C.-based Progress Energy, which operates ash ponds.
"In this economy, that is something that the EPA and White House have to take into account," he said.
The EPA did not comment on the planned lawsuit.