Soil across North Carolina may contain the same chemicals polluting water wells near Buck Steam Station in Dukeville, according to testing data released Monday.

In a blog post on its website, the Department of Environment and Natural Resources released data showing 20 of 24 wells near Allen, Buck and Marshall steam stations fail to pass at least one state standard for drinking water. Tests were intended to evaluate the “distribution of metals and other parameters that may be naturally occurring in the groundwater, and that may also be associated with coal burning activities,” according to the blog post.

Wells tested were a greater distance from coal ash ponds than ones declared unsafe in Dukeville. However, exact locations of the wells were not given in the blog post. The post said exact locations would be given after DENR confirms well owners are aware of test results.

Results show 12 wells received “do not drink” letters from the state for exceeding standards for hexavalent chromium and vanadium. The two chemicals were also the most common contaminant in Dukeville wells declared unsafe.

A total of seven wells received “do not drink” recommendations for vanadium and resample recommendations for hexavalent chromium. One well exceeded state standards for iron and manganese.

Four private wells received incomplete results, with recommendations for resampling.

Tests were conducted with the same methods that declared 72 private wells in in the Dukeville community near Buck Steam Station unsafe to drink or cook with, according to the state’s data.

Zero wells exceeded federal drinking water standards, which are less stringent in some cases than the state’s testing levels.

The state’s standards have been the topic of some criticism, as some are more strict than what’s allowed in municipal water systems. Municipal systems across the state would, in some cases, exceed the state standards, according to 2014 water quality reports.

DENR’s blog post said the testing would be helpful in determining the amount of naturally occurring contaminants, but didn’t explicitly express an opinion on what the tests mean for background levels of chemicals. The post said comprehensive groundwater assessments will ultimately determine whether contaminants in wells are naturally occurring or from coal ash ponds. For months, Duke Energy has claimed the chemicals are naturally occurring. The groundwater assessment for Buck Steam Station is due on Aug. 21.

The source of contamination means little, according to the blog post.

“The source of contamination in a well, whether determined to be naturally occurring or not, does not influence its potential impact on health,” DENR’s blog post stated. “Wells that exhibit constituent concentrations higher than the applicable health screening level, determined by the (Department of Health and Human Services), may represent an increased health risk.”

According to the post, a number of limitations need to be considered as a part of the test results. One consideration cited was that concentrations of metals can vary significantly over short distances.

Wells were selected for the background testing based on four factors, according to the blog post. Factors influencing water well selection included: being located in areas not connected to groundwater beneath Duke’s coal-fired power plant facilities; being positioned across surface water and groundwater divides from the facilities; being situated in the same, geologic units as the coal ash impoundments and already tested wells; and being newer water supplies to minimize the influence of old or poorly constructed wells.

Contact reporter Josh Bergeron at 704-797-4246.