The N.C. Department of Environment and Natural Resources issued Duke Energy a notice of violation Thursday.
ABC11 first obtained photos of the alleged pumping from the environmental group Waterkeeper Alliance last week that appeared to show pumping equipment and hoses leading to a nearby canal and drain pipe.
"I don't know what's going on, but it worries me that things seem to be, seem to be pumping a lot of the liquid in these ponds out," said Kemp Burdette, Cape Fear Riverkeeper.
In a statement to ABC11, Duke Energy said the pumping was intended to lower the water level in the ponds, which contain a slurry of coal ash with toxic heavy metals, as part of a "routine maintenance" program and was allowed under the site's antipollution permit.
State officials said Thursday they have notified municipalities downstream of the pumping at the Cape Fear plant and none have reported problems meeting EPA drinking water standards. However, DENR said it is collecting water samples in the Cape Fear River downstream of the plant to determine if surface water meets state water quality standards.
"We're concerned with the volume of water that was pumped and the manner it was pumped. It did not go through the treatment facility as it should have," said Drew Elliot, Communications Director of the N.C. Department of Environment and Natural Resources.
DENR said Duke is permitted to discharge treated wastewater from the ash ponds into the canal through vertical spillway pipes, known as risers. The structures allow heavier residue in the water to settle out. But DENR said the pumping bypassed the risers.
"We were notified by phone in August that Duke Energy intended to conduct routine maintenance work at these ash ponds," said Tom Reeder, Director of the N.C. Division of Water Resources. "The state's investigation revealed that the pumping activities on-going at this plant far exceeded what would reasonably be considered routine maintenance."
Its notice of violation says Duke could be fined $25,000 per violation per day. However, DENR is also giving Duke 20 days more than the law requires to respond to the notice, raising concerns among some environmentalists.
"I don't understand why DENR is taking such a soft approach here," said Pete Harrison, with Waterkeeper Alliance. "There's no written record or approval for that kind of dumping."
"There remain contradictions in the stories we're getting from DENR and Duke and there are still questions to be answered," Harrison added.
Meanwhile, Gov. Pat McCrory weighed in Thursday evening in his roughest rebuke of Duke Energy yet.
"The violations that we reported today are extremely serious," said McCrory. "We need an explanation from Duke ASAP not only to us, but to the public at large. They've waited far too long to come out of the shadows and explain what they plan to do, and explain to the public some of the issues that they're encountering at this point in time."
Duke Energy still hasn't commented about its violation notice.