Duke scientist’s findings about natural origins of hexavalent chromium reveals new concerns about what may be in your well water.
By Catherine Clabby
New evidence that nature—not leaking coal ash—produces a cancer-causing metal in wells will not derail Duke Energy from providing new drinking water to people living very close to coal waste dumps.
At the same time, the discovery by a Duke University geochemist Avner Vengosh is the latest alarm that unwanted contaminants can lurk in the wells that provide drinking water to the nearly 3 million North Carolinians who depend on well water at home.Those wells often can go untested for decades.
Vengosh’s findings make a strong case that hexavalent chromium found in wells near coal ash impoundments originated not from coal ash but from natural chemical interactions involving water and volcanic rock common to North Carolina’s Piedmont region.
Vengosh and collaborators tested 376 wells close to and distant from North Carolina coal ash impoundments, using scientific forensics to pinpoint the origin of the metal in each place. They found chemical fingerprints in the wells, located in the Piedmont, did not match the chemical profiles of water polluted by coal ash. However, the samples did match water containing substances produced naturally.
Duke Energy senior vice president Harry Sideris this week said the results should provide peace of mind to hundreds of well owners who live near the utility’s coal ash impoundments who were “needlessly concerned that ash basins contributed hexavalent chromium or other substances to their wells.”
But Vengosh is emphatic the new research does not prove coal ash ponds do not contaminate drinking water wells somewhere, or in some way, in North Carolina.
Another study Vengosh and colleagues published in June, in fact, found that unlined coal ash ponds near 21 power plants in multiple states all leaked. And the scientists found elevated levels of arsenic and selenium in surface waters or groundwater near the impoundments, including near 14 properties in North Carolina.
“I’m glad Duke Energy is supportive of my recent work,” Vengosh said. “But they need to address contamination. This is the data. You cannot take only one thing you like from it.”
Hexavalent chromium is a metal once unknown to most North Carolinians. But this past year, the element has played a leading role in very public battles over how state environmental and health regulators have responded to environmental threats from coal ash.
State health experts have disagreed pointedly with leadership of the state Departments of Environmental Quality and Health and Human Services about what amounts of hexavalant chromium could pose a health risk, and how to communicate such risks to the public.
State and environmental officials in 2015 issued do-not-drink advisories when wells were found to contain the metal with concentrations of 0.07 parts per billion (ppb) but withdrew those warnings early this year, saying the risk was not high enough to pose a danger. That prompted anger and distrust among many well owners.
North Carolina’s state epidemiologist resigned in protest after she concluded that state health and environmental officials unfairly attacked the integrity of a state toxicologist who resisted pressure to downplay the health risks of hexavalent chromium. In depositions made public just last week, sworn testimony suggested Gov. Pat McCrory’s office was directly involved in crafting public messages that understated the threat.
That concern about chemical contamination from coal ash was one reason state legislators this summer required Duke Energy to provide new or filtered drinking water supplies to people living within a half mile of any coal ash impoundments on 14 utility properties. The company will abide by that commitment.
“We remain committed to honoring the state law that requires permanent water supplies for those in a half-mile of ash basins,” said Duke Energy spokeswoman Erin Culbert, a spokesman for the utility. “We think that’s the right thing to do for neighbors’ peace of mind.”
Under a revision to the state’s Coal Ash Management Act, people living beyond the half-mile distance could also be eligible to have their water sources replaced if coal ash contaminated their water. But Duke Energy officials repeatedly have said data collected by its contracted experts indicates well water contamination is not a risk.
Amy Brown, a resident of Belmont who lives very close to Duke’s Allen Steam Station in Salisbury, said she welcomes Vengosh’s findings, even though they suggest that Duke Energy is not responsible for the hexavalent chromium in her well. Tests revealed a level of 2.4 ppb in her well, above the .07 ppb that North Carolina toxicologists calculated posed a one-in-a-million cancer risk after many years of consumption.
If people who live far from a coal ash pond learn about unrecognized risks as a result, that is good for everyone, said Brown, a mother of 4- and 11-year-old sons.
“I welcome any new information. Anything we can do to protect people’s health and people’s environment is good,” she said. “If someone else’s water is unsafe, I would be just as concerned for them as well. I want safe water for anyone. No one should fear having a child exposed to cancer-causing water.”
At the same time, Brown remains committed to her position that Duke Energy should excavate all coal ash waste from its properties, rather than keeping some waste in place and capping the dumps, as Duke has favored.
Wider well worries
News that hexavalent chromium might be more widespread in private wells is only the latest warning of previously unrecognized contaminants in North Carolina wells. Just last month a North Carolina State University scientist published a study finding that, due to geochemical conditions, hundreds of thousands of Piedmont drinking water wells likely have elevated levels of manganese. The metal has been associated with, among other things, increased incidence of heart defects among newborns.
Vengosh, the Duke scientist, says he thinks North Carolina state government should invest money and effort into assessing how widespread hexavalent chromium contamination is in private drinking wells. But that would take more testing than is currently mandated.
People who run municipal drinking water supplies are required to test for a wide range of possible contaminants and keep their contamination limits below federal standards known as maximum contamination levels (MCLs). State environmental health officials have said they favor applying such standards to assess risks in public drinking water supplies and private wells.
But when it comes to private wells, there is limited government regulation over well water.
It’s only been since 2008 that North Carolina has required the testing of only new drinking water wells. A long list of potential troublemakers must be measured in the water, including coliform bacteria, arsenic, barium, lead, iron, manganese, mercury, nitrate and selenium. The standards require testing for totals of all chromium compounds, but do not require specific testing for hexavalent chromium.
“It is a basic test including common metals, nutrients and bacteria, but does not include the many other pesticides, industrial chemicals and other compounds that can be problems when wells are in proximity to a source of contamination,” said Katie Hicks, assistant director of Clean Water North Carolina.
North Carolina does recommend testing wells annually for fecal coliform bacteria, every two years for heavy metals and volatile organic compounds and every five years for pesticides. The state provides information on potentially dangerous contaminants too.
Owners carry that burden of monitoring the risks with testing guidance and assessment available from county health departments.
If a well has not been tested for five years, Wake County recommends what it calls a “first-timer’s package,” which includes testing for coliform bacteria, inorganics, volatile organic compounds, pesticides and herbicides. The cost is $275 with discounts available to residents with low incomes.
North Carolina rules on well testing match other states’ although some also require wells be tested each time a home is sold, said Hicks, who highly recommends that well owners get their water sources tested at least every three years.
Private well owners, she said, are ”particularly vulnerable when it comes to drinking water contamination.”
Consider testing well water more than once a year when:
- A family member is pregnant or nursing
- An unexplained illness emerges
- Neighbors find a dangerous contaminant in their water
- Changes emerge in water’s taste, odor, color or clarity
- Chemicals or fuels spill nearby
- You replace a part within or repair the well