Inactive coal ash impoundments are leaking toxic chemicals into nearby groundwater and surface waters in five Southeastern states, according to a new study.

Duke University researchers reported that data show high levels of toxic heavy metals, including arsenic and selenium, in the surface water and groundwater near coal ash lagoons at 21 power plants, including two sites in Virginia. Contaminant levels in 29 percent of their surface water samples exceeded Environmental Protection Agency standards for drinking water and aquatic life, researchers said.

The study, published June 10 in the journal Environmental Science & Technology, was underwritten by the Southern Environmental Law Center. The environmental group has filed lawsuits to press for the cleanup of ash ponds in four states, including Virginia, and is calling for stricter safeguards.

Avner Vengosh, professor of geochemistry and water quality at Duke and a study author, said the university has been studying coal ash since the first catastrophic spill from a ruptured impoundment in Tennessee eight years ago.

In this study, Vengosh said, researchers found that all of them are leaking to some degree. The study does not mention whether the ponds are lined, often with clay, or unlined. Vengosh said that’s because the researchers don’t think the clay liners used in some of the newer ponds are adequate to prevent leaking.

The study looks at contaminants found in monitoring wells and doesn’t address the recent controversy over whether coal ash is tainting drinking water wells near the impoundments. Vengosh said he and colleagues plan next to examine that question.

Power plants have routinely stored their ash in onsite landfills or impoundments, where rainwater has collected on top of the water initially used to carry ash to the ponds. But, after two such impoundments in Tennessee and North Carolina failed, sending millions of tons of coal ash into local waterways, the EPA issued a rule that all inactive ponds must be drained and capped by 2018 or face stricter requirements, such as more advanced liners and long-term monitoring.

Dominion Virginia Power runs several plants with coal ash impoundments in the Bay watershed. The company already is in the process of draining lagoons at its Possum Point plant near the District of Columbia, and at its Bremo Bluff station outside of Charlottesville, VA, which was one of the sites included in the Duke study. The company plans to cap the ash deposited in the bottom of each impoundment with clean dirt and impermeable liners meant to prevent water from soaking through the waste.

“We’re reviewing this study,” Dominion spokesman Robert Richardson wrote in an emailed statement. “We’re happy to speak to residents who have concerns about their groundwater… our plan to close coal ash ponds is safe and protective of groundwater.”

Dominion is seeking permits from the Virginia Department of Environmental Quality to close its coal ash ponds and landfills at the Chesapeake Energy Center in Chesapeake and the Chesterfield Power Station in Chester. The Chesterfield lagoon is the other Virginia site where Duke researchers found contaminants in nearby surface water.

Dominion’s timeline for closing the impoundments was delayed this spring by changes in the federal rule that first triggered their closure. The court is expected to approve an agreement between the EPA and environmental groups to revise the coal ash rule, which would require companies like Dominion to monitor groundwater around any closed ponds for 30 years— and to clean up any coal ash contaminants that might be detected there.

Dominion has had monitoring wells in place for decades, but Richardson said the company plans to increase the number to comply with the EPA rule.

“We have identified localized impacts on station property, but no impacts have been identified offsite,” Richardson wrote in the statement. “Should results indicate groundwater impacts during that time, Dominion will be required to clean up the groundwater and provide additional protections.”

Dominion officials said they would have a more thorough response to the specifics of the Duke study after completing their own analysis of it.

Though SELC funded the study, Vengosh said the funders “have zero role in our science,” which he said was reviewed by five independent peers.

“One of the important objectives of this paper is to try to do it independently,” Vengosh said.

Last month, advocates and officials sparred over conflicting tests of well water drawn from homes near the Bremo and Possum Point stations — leaving homeowners confused about whether their water was safe to drink. Some tests done with the help of environmental groups found high levels of lead and low but detectable concentrations of hexavalent chromium, a known carcinogen.

Dominion responded by pointing out that a third-party review of well tests concluded the company’s ash ponds aren’t a potential source of the contamination found. The review, done by private contractor for Prince William County, suggested the lead detected in the one well could have come from aging household pipes.

Vengosh said his research team hopes to resolve the well-testing dispute next, applying the same technology to drinking-water samples that was used in this study linking groundwater contaminants to coal ash.

For the latest study, the researchers used isotope fingerprints to trace elements found in nearby groundwater and surface waters back to the coal ash ponds. They also looked for what they said are leading indicators of coal ash contamination, such as boron and strontium, which are more water-soluble and often the first to leak into the surrounding area.

“Boron could be an early indicator that other contaminants are coming,” Vengosh said. And it could be used as a “forensic tracer” to link a suite of contaminants found in groundwater or surface water back to coal ash, with the technology that the study used.

“The science to say, ‘This contamination in your water is from coal ash’ is what we are trying to build,” Vengosh said of the research, “to have a very clear yes or no.”