Contaminants in Dayton water above what some states consider safe

City officials insist water ‘is excellent’ and they’re taking steps to protect it.

Test results for toxic, human-made contaminants in Dayton’s drinking water remain well below current federal advisory guidelines but repeatedly tested at or above limits established or proposed by other U.S. states, the Dayton Daily News found in an examination of city data.

City officials test water from Dayton’s two treatment plants each month for per- and polyfluoroalkyl substances, or PFAS. Studies have linked at least two types of PFAS — known by the acronyms PFOA and PFOS — to several health problems, including low birth-weights and various cancers.

The substance was used in firefighting foams at Wright-Patterson Air Force Base and the Dayton Fire Training Center on McFadden Avenue. Both are near the city’s Mad River well field.

The Dayton Daily News Path Forward project digs into solutions for the most pressing issues facing the community, including protecting the region's drinking water that serves more than 400,000 people in Montgomery County. This story examines new data from the city about PFAS contamination levels.

The newspaper met with city officials to better understand the test results. The Dayton Daily News also asked an expert at Wright State University’s Department of Earth and Environmental Sciences to review the data.

Montgomery County officials called on the city earlier this month to release more information about water quality and their plans to address the contamination. City leaders have repeatedly said the water is safe to drink, despite the newly released higher test results.

“The EPA themselves — they are a pretty strict regulatory entity — are saying and reinforcing that our water is excellent water quality,” said Michele Simmons, environmental manager for the city of Dayton.

Higher results

The U.S. Environmental Protection Agency and the state of Ohio currently do not regulate PFAS. But the federal agency advises PFAS levels should not exceed 70 parts per trillion, and city officials say they follow that guidance.

The city’s Miami Water Treatment Plant is clearly below that level, said Abinash Agrawal, the Wright State professor who reviewed the test results.

“For the Ottawa plant … it’s definitely below 70 parts per trillion, but tests slightly elevated than the Miami plant,” Agrawal said. “Some of the water leaving the Ottawa treatment plant has levels above what other states are following.”

Previously the highest level of PFAS publicly known to be measured leaving the Ottawa Water Treatment Plant was about 12 parts per trillion in March 2018. But Dayton tested water leaving the Ottawa plant in September 2018 and found PFOA and PFOS combined at nearly 19 parts per trillion, according to the new data obtained by the Dayton Daily News.

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Dayton officials say this amount of PFAS is so minuscule that it’s essentially the same as other measurements that were as low as 7.59 parts per trillion in April 2018. One part per trillion is roughly equivalent to a grain of sand in an Olympic-sized swimming pool, Dayton officials said. Therefore, they wouldn’t consider the difference between April and September as a “spike.”

“We are still looking at this to find the way that our levels stay the same or are further reduced,” said Tammi Clements, Dayton deputy city manager. “We want to see it at zero and we’re being very proactive.”

The Dayton Daily News had asked for more updated numbers earlier this year, but the city declined to release them until now, citing a lawsuit it filed against PFAS manufacturers, including the 3M Company.

“What we’ve tried to be very transparent about is what’s going into the plant and what’s coming out of the plant,” Clements said.

She encouraged residents to visit the U.S. EPA’s website to learn more about PFAS.

Lower levels proposed

Other parts of the federal government have proposed lower levels than the U.S. EPA.

A 2018 report from the Centers for Disease Control and Prevention proposed health thresholds for PFOA and PFOS about 10 times lower than the U.S. EPA’s health threshold. That CDC proposal called for PFAS levels lower than what was found leaving the Ottawa plant last summer.

Some states are setting their own lower limits on PFAS but Ohio has not. The Michigan Science Advisory Board said, “if one accepts the probable links between PFOA exposure and adverse health effects … then 70 (parts per trillion) in drinking water might not be sufficiently protective.”

Michigan officials set a screening level of 9 parts per trillion for PFOA and 8 parts per trillion for PFOS, according to a collection of state data from the Natural Resources Defense Council, an environmental advocacy group that lobbies for lower PFAS thresholds and is critical of the U.S. EPA.

Other states have proposed lower-than-federal limits, according to the NRDC. New York, for example, has proposed enforceable standards for drinking water at 10 parts per trillion for both PFOA and PFAS.

“Federal lawmakers are now asking the EPA to come up with another parameter that we call maximum contaminant level, which is a very clear guidance,” said Agrawal, the WSU professor.

Proactively shut down wells

Dayton says its water protection program is a national model and used by the EPA as an example for other communities. That includes wells to monitor for contaminants both inside and outside of the area where the city pumps drinking water.

The city has proactively shut down drinking water wells when PFAS has been detected, city officials said, starting in 2016.

The detection system worked exactly as it was supposed to, Clements said, and the city began working aggressively once it was detected.

They still are working to determine the contamination origin in some parts of the Mad River well field. A May 2017 sampling of groundwater monitoring wells at Tait’s Hill found at least one sample registered 1,200 parts per trillion, city officials previously said.

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But earlier this month Montgomery County officials gave the Dayton Daily News a map that says a monitoring well — which is used only to sample the water quality and isn’t used for drinking — in the same area picked up a PFOS reading of 1,500 parts per trillion in March 2018.

“It’s a significant amount,” Agrawal said.

Dayton city officials confirmed that reading, but said production wells around that monitoring well were shut off at the first sign of contamination and remain off today. The newspaper has requested more recent testing data.

“We are taking the utmost precaution to prevent any, not just PFAS, but any of these contaminants from getting in our water,” Simmons said.

About the Path Forward

Our team of investigative reporters digs into what you identified as pressing issues facing our community. The Path Forward project seeks solutions to these problems by investigating the safety and sustainability of our drinking water. Follow our work at or join one of our Facebook Groups.

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