A coalition of environmentalists has been sounding the alarm about a plan the Tennessee Valley Authority is considering for storing coal ash involving ten cites.

The TVA has announced its closing down ash storage at ten power plants.

The Southern Environmental Law Center and ten other groups have been warning there’s a danger that toxic chemicals at sites near rivers in Tennessee, Kentucky, and Alabama will leach into groundwater if TVA decides to leave the ash in place, drain it and cover it. The groups said it would be safer if TVA moved the ash into lined storage facilities

A TVA spokesman said the agency has not made a decision yet on what to do. He said federal environmental officials say either method of storage is safe if done properly.