North Carolina officials are advising dozens of residents near Duke Energy coal ash dumps not to drink or cook with water from their wells after tests showed contamination with toxic heavy metals.

The state Department of Environment and Natural Resources said Tuesday that tests of 87 private wells near eight Duke plants showed results that failed to meet state groundwater standards.

A law passed after last year's spill into the Dan River required the North Carolina Department of Environment and Natural Resources to sample wells within 1,000 feet of Duke's 32 coal ash dumps.

Rowan County Environmental Health Manager Tad Helmstetler confirmed 20 families living near Buck Steam Station in Salisbury are getting letters advising them not to consume their water. Several of the letters cite high levels of vanadium, a naturally occurring element found in coal classified as hazardous by federal health officials.