"Environmental groups say they will sue Duke Energy for not telling the public what would happen if any of its dozens of coal ash dams fail.
Duke’s 31 North Carolina coal ash basins hold 111 million tons of ash in water-filled ponds. Ash holds metals that can contaminate rivers, lakes and groundwater.
The massive rupture of a Tennessee Valley Authority dike in 2008 first made coal ash an environmental issue. Duke spilled its own ash into the Dan River in 2014, although not from a dam collapse, and paid $102 million to settle federal criminal charges.
The Environmental Protection Agency adopted a rule in 2015 that requires utilities to file emergency action plans for ash spills. Utilities have to post information on their compliance with the rule on public websites."