RALEIGH, N.C. (AP) — The nation's largest electricity provider, state regulators and an environmental group issued differing data Thursday about the levels of toxins detected in a North Carolina river following a massive spill of coal ash.

Test results released by the N.C. Department of Environment and Natural Resources and Duke Energy showed arsenic and other potentially harmful contaminates were detected in the Dan River, but at levels considered safe for both people and fish.

The state and Duke cooperated to collect samples from the same sites, the closest about two miles downstream from the power plant where about 82,000 tons of toxic coal ash mixed with 27 million gallons of contaminated water has spilled into the river since Sunday. The spill produced a plume of contamination that coated the river bottom in sludge and turned the water slate gray for miles.

Water samples tested by a lab hired by the Waterkeeper Alliance contained levels of arsenic nearly nine times higher than the state's results, along with readings for other hazardous chemicals at levels far above state standards. Those samples were collected Tuesday just feet from where the toxic waste spewed into the river, the environmental group said.

Testing of tap water in Danville, Va., the closest city downstream at about 20 miles from the spill site, showed the contaminates were successfully being filtered from the municipal water supply.

Tom Reeder, director of the N.C. Division of Water Resources, said the state's test results did not yet give the Dan a clean bill of health. However, he said the findings that water quality in the river met state standards were very encouraging.

Asked why his agency didn't collect samples closer to the source of the spill, where the toxic chemicals would be less diluted and more likely to exceed state standards, Reeder responded that the goal of the testing was not to find out whether Duke had violated environmental laws or trigger hefty fines. He said there would be time later to sort that out.

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"Obviously, if we took it directly underneath where the discharge is entering the water, particularly in a case like this, you might find some exceedances," Reeder said. "But what we're really interested in is finding out what the actual impact is in the environment, and in order to do that you have to allow for some mixing so you get an accurate picture."

Hundreds of workers continued Thursday to try to permanently seal a large drainage pipe that runs under a 27-acre pond where Duke had dumped ash from the coal-fired furnaces at its Dan River Steam Station for decades. The leak triggered when that pipe collapsed. It has slowed to a trickle, as most of the liquids had either leaked or been pumped away. Duke said it could not provide an estimate for when the spill would be completely contained.

North Carolina Gov. Pat McCrory traveled to the plant Thursday and made his first public statements on the disaster. The trip was not listed on McCrory's public schedule.

"This is a serious spill and we need to get it under control as quickly as possible," McCrory said. "Our top priorities are ensuring the health and safety of the public as well as the wildlife in the Dan River vicinity and the river itself, and the best way to do that is to get this controlled and cleaned up."

McCrory said Duke officials had agreed to "spare no expense" to stop the leak. He said he had also been in contact with Virginia Gov. Terry McAuliffe and that officials in the two states were cooperating on the spill response.

McCrory worked for Duke for 28 years before retiring to launch his first campaign for governor in 2008. Watchdog groups have questioned whether the Republican governor's close ties to Duke executives have influenced how aggressively his administration regulates the company.

The test results released by the state and Duke showed water samples contained arsenic at up to 40 parts per billion. The state limit in rivers and lakes is 50 parts per billion. Readings for lead were recorded at 23 parts per billion, just below the state limit.

The state did note readings for copper were above state levels, but because it is a naturally occurring element in North Carolina waters, the state said further testing would be needed to see if the ash spill was to blame.

The U.S. Environmental Protection Agency has also conducted extensive testing. So far, those results have not been made public.

The numbers released by Duke and state regulators were in sharp contrast to findings by the Waterkeeper Alliance, an environmental group founded by Robert F. Kennedy Jr.

The Alliance said its samples showed arsenic at nearly 350 parts per billion, seven times the level the state says is safe for aquatic life. The group also reported readings of lead at 129 parts per billion, more than five times the state limit.

"If a terrorist group committed in North Carolina — for ideological reasons — a crime that Duke Energy has committed for profit, our nation would consider it an act of war against our country," Kennedy said.

At Duke's headquarters in Charlotte, about 30 protesters marched and carried signs urging Duke to "Clean Up Coal Ash Now." They said the company was negligent in the spill.

"Duke has assured us that these coal ash dumps are safe," said Bill Gupton, chairman of the Central Piedmont Group of the Sierra Club. "But they're not."

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Associated Press writer Mitch Weiss reported from Charlotte.

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