Duke Energy, the giant utility whose spill of toxic waste into a North Carolina river last month is under federal investigation, released wastewater last week from a second site near Raleigh that state regulators said could be illegal. http://www.nytimes.com/2014/03/16/us/north-carolina-investigating-another-duke-energy-site.html?ref=us

Aerial photographs of two Duke coal ash ponds at the head of the Cape Fear River show portable pumps and hoses that appear to be siphoning water into a canal leading to the river.

A spokesman for the state’s Department of Environment and Natural Resources said on Saturday that its inspectors noticed the pumping while on a site visit last week. “We are investigating the utility’s actions,” the spokesman, Drew Elliot, said in an email. “While routine maintenance is allowed under the permit, discharge of untreated wastewater could be a violation.”

A spokesman for Duke, based in Charlotte, 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.

After a huge coal ash leak into the Dan River coated 70 miles of river bottom last month, state regulators cited Duke for violating water pollution laws at its plant in Eden, N.C., and five other sites, where ash from burning coal to generate electricity is held in large containment ponds.

The Dan River spill, the third-largest disaster of its kind on record, brought intense scrutiny to how Duke stored coal ash at 14 power plants throughout North Carolina, as well as to what critics called an overly cozy relationship with state regulators. But the state environmental agency, as well as Gov. Pat McCrory, a Republican and former longtime Duke executive, has responded to public outrage by calling for tougher regulation of coal ash.

Duke said this month that it would move its coal ash at several sites to more secure pits farther from public waterways. It also said that at its retired coal plants, which include the Dan River and Cape Fear River sites, it would accelerate “the removal of water from the ash ponds” within 24 to 36 months after obtaining the necessary permits.

The two ponds at the Cape Fear River plant, near Moncure, N.C., have permits for vertical pipes that drain water from the top of the ponds when rain and runoff rise, similar to a bath sink’s overflow drain. The principle of a settling pond is that toxic material sinks to the bottom over time, leaving cleaner water on top. Pumping out deeper water risks removing impurities before they have settled.

Environmentalists said a possible motive for Duke to pump water from its ponds now, before it has obtained permits to drain them, is to reduce the volume of water requiring treatment, lowering its eventual costs.

“This is a way of disposing of that water without the state knowing, without the public knowing and without having any limits placed on that discharge,” said Lisa Evans, a senior counsel with Earthjustice, an advocacy group.

Peter Harrison, a staff attorney with the Waterkeeper Alliance, which took the aerial photos on Monday, said that if Duke were acting improperly, it was an audacious move at a time when company officials and state regulators have been subpoenaed to appear before a grand jury in Raleigh this week, which is investigating the Dan River spill.

But Duke’s spokesman, Jeff Brooks, said that the activists were wrong, that the discharge was permissible maintenance and that state regulators had been notified by the power company. “They’re lowering the water to conduct the maintenance they need to,” Mr. Brooks said. He could not say what type of maintenance was being performed or when state regulators had been notified.

His statement appeared to contradict the environmental agency. Its spokesman said that inspectors had come upon the pumping during a site visit.

Mr. Harrison of the Waterkeeper Alliance scoffed at Duke’s explanation. “To label the secret, unmitigated, intentional discharges of untold amounts of highly toxic wastewater as ‘routine maintenance’ is beyond ludicrous — and it is a federal crime,” he said.