In this Wednesday, Feb. 5, 2014 photo, signs of coal ash swirl in the water in the Dan River in Danville, Va. Duke Energy estimates that up to 82,000 tons of coal ash has been released from a break in a 48-inch storm water pipe at the Dan River Power Plant in Eden N.C.Over the last year, environmental groups have tried three times to use the federal Clean Water Act to force Duke Energy to clear out leaky coal ash dumps. Each time, the N.C. Department of Environment and Natural Resources has effectively halted the lawsuit by intervening at the last minute to assert its own authority to take enforcement action. In two cases, the state has proposed modest fines but no requirement that the nation's largest electricity provider actually clean up the coal ash ponds. The third case is pending. (AP Photo/Gerry Broome) MORE LESS