DURHAM, N.C. – North Carolina environmental regulators acknowledged Sunday that they had erroneously reported results of early toxic tests in the Dan River after a huge coal ash spill, specifically, that arsenic was within safe levels.

The North Carolina Department of Environment and Natural Resources said it had incorrectly reported that results of water samples taken Feb. 3 were within state standards for arsenic, a toxic heavy metal. In fact, the agency said, two samples exceeded the standard of 10 micrograms per liter.

“We made an honest mistake while interpreting the results,’’ Tom Reeder, director of the agency’s Division of Water Resources, said in a statement Sunday afternoon.

The leak at a retired Duke Energy power plant dumped up to 82,000 tons of ash into the river in North Carolina and Virginia. It was reported Feb. 2.


Tests of samples collected since Feb. 3 have found arsenic levels within the state standard, and those levels have continued to drop, the statement said. The department has recommended that people “avoid prolonged direct contact’’ with the Dan River in the spill area until further notice.

“The bottom line remains that we are concerned for the long-term health of the Dan River,’’ Reeder said. “We will continue to test the water in the river as we assess the spill’s impact and determine the most appropriate ways to clean up the river. We are in this for the long haul.’’

The state had said Friday that it had earlier found levels of arsenic, copper, iron and aluminum above state standards for surface water quality. The state failed to note that it was correcting the arsenic levels inaccurately reported the previous Monday.

Environmental groups have criticized the state and Duke Energy, the giant utility responsible for the spill at the company’s retired coal-fired plant on the Dan River in Eden, N.C., near the Virginia border. One group, Waterkeeper Alliance, says its tests of water samples have found levels of arsenic, lead, chromium and other heavy metals that far exceed safety standards for humans or wildlife.


Environmentalists have criticized the Department of Environment and Natural Resources for working closely with Duke on spill response and water sampling. The agency sued the utility in August for improper discharge of coal ash from containment basins at 14 Duke-owned plants, including the Dan River facility.

Waterkeeper Alliance and the Southern Environmental Law Center say the coal ash basin at the Dan River plant, shut down in 2012, has been leaking ash into the river in small but steady amounts for years. The massive Feb. 2 spill was caused by a ruptured stormwater pipe beneath the 27-acre containment basin, according to Duke.

Municipal water officials downstream have said normal treatment and filtering procedures have rendered water from the Dan River safe to drink. But environmental groups say the spill poses an immediate and long-term threat to humans, wildlife and the environment.

In addition to coal ash, 27 million gallons of contaminated coal ash basin water was dumped into the river. Environmental groups say arsenic and other heavy metals have settled into sediment on the river bottom, threatening the river’s health for years.


Ash flow from the spill site has been reduced but has not yet been stopped, according to the Department of Environmental and Natural Resources statement.

david.zucchino@latimes.com