— Since late last year, state environmental regulators have been working with private laboratories to test the water quality of wells near the unlined dumps where Duke Energy stores coal ash, the byproduct of electricity generation.

As of July 8, officials at the Department of Environment and Natural Resources identified 446 wells for testing. Of the 285 wells with results back in to the state, about 93 percent show water that exceeds federal or state health standards for some trace elements. After evaluations by state health officials, more than 200 wells have received "do not drink" recommendations.

Many of the elements that have prompted the state to issue do-not-drink recommendations occur naturally in soil and geologic formations absent any intervention from humans.

Zoom to a coal ash pond Asheville Steam Plant Belews Creek Steam Station Buck Steam Station Cape Fear Steam Plant Cliffside Steam Station Dan River Steam Station Lee Steam Plant Marshall Steam Station Mayo Steam Plant GG Allen Steam Station Riverbend Steam Station Roxboro Steam Plant Sutton Steam Plant Weatherspoon Steam Plant Reset Safe Retest Don't drink SafeRetestDon't drink Explore the coal ash tests Find out more about the state's ongoing tests of private and public wells near North Carolina's 14 coal ash locations. Click on a well marker to see the recommendations state health officials have issued in response to the tests, or select a Duke Energy plant to get an overview.

State officials are also in the process of retesting dozens of wells for a carcinogenic element called hexavalent chromium because the original labs weren't able to detect it with enough precision. Hexavalent chromium is rarely found in the environment and is a common industrial waste. It's also found in coal ash.

Because the tests are ongoing and results are still rolling in, WRAL News' map of well test results will be updated when state officials supply new data.