DUKEVILLE, N.C. — The sweet tea served in the tidy kitchen of Joanne Thomas’ antebellum home comes with an ominous warning.

“It’s made with bottled water,” says Thomas, a spry 71-year-old. “But the ice comes from our well.”

For more than 80 years, the Thomas family has lived on a farm that abuts three open-air pits containing 6.1 million tons of ash from the coal-fired boilers of Duke Energy’s Buck Steam Station. Built in 1926, the hulking plant towers over the Yadkin River an hour’s drive from the Charlotte headquarters of the nation’s largest electricity company.

Since 2011, Duke and North Carolina environmental regulators have known that groundwater samples taken from monitoring wells near the Thomases’ home and others in Dukeville contained substances ”“ some that can be toxic ”“ exceeding state standards.

The state could have required Duke to implement a cleanup plan to prevent spreading contamination. That never happened, state regulators said, because they weren’t certain whether coal ash production was to blame or if the substances were naturally occurring.

Those living near the plant were never warned and continued using their well water for drinking, bathing and cooking. Now the Thomases and their neighbors wonder not only what’s in their water, but whether it’s harmed them or their children.

In the wake of a massive Feb. 2 coal ash spill at another Duke plant, state regulators, environmental activists and Duke officials have been testing the water supplies for some of the 150 homes in Dukeville.

Both the state and Duke said their own tests found no significant problems. But the findings conflict with those of the environmental group Waterkeeper Alliance, whose tests show levels of some potentially toxic substances above state standards.

“I feel like we’re due answers,” said resident Sherry Gobble. “I just need to know my children are safe.”

Coal ash is the byproduct left behind when coal is burned to generate energy. It contains a witch’s brew of toxic substances, including arsenic, selenium, chromium, beryllium, thallium, mercury, cadmium and lead.

Though there are no known studies linking coal ash pits to adverse health effects, residents here are worried nonetheless because of years of cancer diagnoses and other ailments, including several birth defects.

In the 1990s, the community made news after a radiologist reported finding nearly a dozen cases of brain cancer dating back years among those either working at Buck or living nearby. An ensuing study looked for links to electromagnetic radiation from power lines but found no connection. The lead researcher said other potential causes weren’t examined.

In the Thomas family, Joanne said she had a pituitary tumor removed from the base of her brain in 1996. Her husband, Ron, long retired from a job where he worked with industrial chemicals, survived prostate cancer and is undergoing treatment to remove mercury, cadmium and selenium from his blood. Records show one of Ron’s brothers died of a brain tumor at 51. Ron’s great nephew died of brain cancer at 37. Both also lived in Dukeville.

Richard Clapp, a nationally known epidemiologist who studies drinking water contaminates, said that while such illnesses are “unlikely” a coincidence, it’s impossible to point to a specific cause without further study.

The families in Dukeville want just that. They also want Duke to pay to extend municipal water lines out to where they live, as the company did in a neighborhood near Wilmington after local government officials raised alarm that coal ash contamination was approaching residential wells.

“I think that we assumed that everything was going along well and fine … because nobody is telling us otherwise,” said the Thomases’ daughter, Melissa Shue.

Duke officials said they have seen no evidence those living near its ash pits are at any risk, and insist the groundwater is flowing away from neighboring properties.

“If we had any indications that we see with concerns to your health, Duke Energy would be proactive,” Duke spokeswoman Erin Culbert told some 50 residents who gathered at a volunteer fire department in May to discuss the ash pits.

Culbert told The Associated Press that the company’s own tests of some Dukeville residential wells confirm the wells are safe and “show no indication the plant’s ash basins have influenced their water quality.”

The February spill at Duke’s power plant near Eden, 80 miles northeast, coated North Carolina’s Dan River in toxic sludge and ignited debate about the safety of Duke’s 33 coal ash dumps across the state. Nationally, there are more than 1,100 such dumps.

With federal officials still debating rules to govern the treatment, storage and disposal of coal ash, regulation has largely been left up to individual states. In North Carolina, political pressure is building for new legislation that could require Duke to dig out the ash from unlined pits and move it to lined landfills.

Duke has agreed to remove ash from the Dan River site and three others. But the company is studying what to do with the other 10, including the Buck Steam Station. The pits at Buck, the oldest dating to the 1950s, are ringed by 14 monitoring wells that are sampled by Duke three times a year and tested at the company’s lab for contamination.

Those test results, released by the N.C. Department of Environment and Natural Resources following a public records request, show that since 2011 the wells failed to meet state groundwater standards on 226 readings out of more than 2,500 ”“ most commonly for high amounts of manganese and iron but also for some boron.

One monitoring well, located about 20 feet from the Thomas property line and about 400 feet from the family’s well, exceeded groundwater standards for chromium on all three tests in 2011. One reading was nearly three times the state standard, while the others were just above it.

In an August court filing, state regulators cited some of those findings as evidence the company was in violation of state environmental standards. However, the company still has not been ordered to take corrective action.

With the chromium in particular, North Carolina Division of Water Resources spokeswoman Susan Massengale said officials have been trying to determine whether the levels were due to chromium occurring naturally in the environment or industrial processes.

Both Massengale and Culbert, the Duke spokeswoman, noted that the company’s monitoring well near the Thomas farm has not detected any chromium at all since the 2011 readings.

Chromium is a metallic element that occurs naturally in the environment but can also be produced by industrial activity. Its most toxic form ”“ hexavalent chromium or chromium-6 ”“ is known to cause lung cancer when inhaled, and the U.S. Environmental Protection Agency says it is likely to be carcinogenic when ingested.

The federal Agency for Toxic Substances and Disease Registry notes that chromium can change from one form to another in water and soil, depending on conditions. Both types have been detected in the Waterkeeper Alliance tests.

In March, April and May, the group took samples from 15 wells used by families in Dukeville and from seepage on the Thomas family’s land. The results were analyzed by accredited independent labs, and according to lab reports provided to the AP:

”¢ Water from the Thomases’ kitchen faucet contained chromium at nearly four times the state limit for groundwater and exceeded the state limit for arsenic. Massengale said household plumbing lines and fixtures may have affected the results.

Ӣ Samples taken from the wellhead at the Thomas farm and 14 wells used by nearby homes contained some hexavalent chromium, though at amounts considered acceptable by state regulators. Wells at some of the homes exceeded state groundwater standards for total chromium, lead, iron and manganese.

”¢ A sample taken from water seeping up in the Thomases’ cow pasture contained chromium at nearly 10 times the state groundwater standard, lead at more than six times the standard, manganese at 562 times the standard, iron at 1,086 times the standard and boron at 1.5 times the state standard.

Avner Vengosh, a professor of geochemistry and water quality at Duke University, said the readings from the cow pasture leave little doubt that coal ash pollution had spread.

“The preliminary data and high boron content in the seep sample collected from the farm show evidence for migration of effluents originated from the coal ash pond,” Vengosh said.

Duke responded by touting its own results collected in May from eight homes in Dukeville. With the exception of the Thomases, the homes the state and Duke tested were not the same ones the Waterkeepers tested earlier.

The company reported an exceedance of state groundwater standards for zinc at one home. Duke’s testing also found trace amounts of chromium-6 in five of the eight wells, but Culbert said those findings were “extremely low.”

The state reported very similar results to Duke’s, though it did not test for hexavalent chromium.

Duke declined to release the specific locations it tested, citing the need to protect the privacy of homeowners. Joanne Thomas said Duke shared their test results with them, but the company’s readings did little to allay her worries.

North Carolina’s limit for total chromium in groundwater is 10 parts per billion, and it regulates chromium-6 under that standard.

Clapp, the epidemiologist, argues there is no safe level of chromium-6 because it’s a known carcinogen. He advised residents to avoid consuming water from their wells even after looking at Duke’s results.

“Citizens are right to be concerned about these measured levels of hexavalent chromium in water from residential wells,” Clapp said.

For many Dukeville residents, the test results have triggered new worries about staying in the tight-knit community their families have called home for generations.

Bryant Gobble, Sherry’s husband, grew up a few doors down from the Thomases and used to fish and swim in the ash pits as a boy.

“We just thought that coal was a natural deposit. It comes from the earth, so we thought it was OK,” he said.

The Gobbles say their family has long suffered medical issues their doctors can’t explain. Their 9-year-old son was born with a cyst at the base of his brain. Their two children also suffer chronic nosebleeds; a red towel is kept on hand in the laundry room.

“I’ve even said to Bryant before, ”˜This is not normal.’ And, he’s like, ”˜Yes it is. I had nosebleeds all the time when I was little,’” Sherry Gobble said.

Duke retired the last of its coal-burning furnaces at Buck last year, replacing them with boilers fired by natural gas.

Among the options Duke has proposed for Buck would be to drain its remaining ponds and leave the ash in place, covered with plastic sheeting and a layer of soil. If it is forced to move the ash from all its sites in the state, the company has warned that customers, not shareholders, would likely foot the $10 billion bill.

For now, some families in Dukeville say they are relying on bottled water and taking very short showers. Others are considering abandoning their homes. That’s especially difficult for 79-year-old Ron Thomas, who was born on the farm and has lived there nearly all his life.

He and Joanne had always seen the land as their legacy to their daughters and grandchildren, who have talked about building their own homes among the ancient oaks and green rolling hills.

Now, he said, “I think all that is out of the question.”

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