The PFAS concentrations of more than 10,000 parts per trillion found in the recent tests are well above EPA health advisory standards, which have been set at 70 parts per trillion.

A new series of tests found record levels of a toxic and possibly cancer-causing chemical compound in groundwater in private wells just north of Tucson International Airport.

While the contamination appears to be moving toward city drinking wells on Tucson’s south side, the pollution doesn’t pose any immediate health risk to water users, Tucson Water officials say.

Per- and polyfluoroalkyl -contaminated water has previously been found in tainted drinking wells from Tucson’s south side to Marana, but never in these concentrations. The substances are often more commonly referred to as PFAS.

Tucson Water Director Tim Thomure said the contamination levels — which exceed 10,000 parts per trillion — are significantly higher than have been recorded locally.

He stressed on Thursday that the water sampled is not part of the water delivery system and does not present an immediate threat to the city’s drinking water supply.

The tests were performed at several privately owned wells, either active or inactive, in the area just north of the Arizona Air National Guard facilities at Tucson International Airport. The wells are not in Tucson Water’s system.

“It is part of the aquifer that does not have any production wells used by the city or by Tucson water. These concentrations are not in our drinking water or even adjacent to our drinking water,” Thomure said. “It is something that needs to be addressed so that it doesn’t become connected to our drinking water.”

On Tuesday, the Tucson City Council discussed in an executive session seeking to make changes to a decades-old consent agreement.

The consent decree — which dates to 1991 — is a series of agreements between the city of Tucson, the U.S. Air Force, and the Environmental Protection Agency on how to clean up trichloroethylene or TCE contamination at the Tucson Water Airport Remediation Project plant. The water is treated to strip out the TCE.

As part of the agreement, the city is required to take the treated water and send it back to its customers with the only exception being if the water fails to meet federal and state water safety standards.

However, the PFAS concentrations of more than 10,000 parts per trillion found in the recent tests are well above EPA health advisory standards, which have been set at 70 parts per trillion.

City Attorney Mike Rankin said the council authorized his office to attempt to modify the consent agreement so that the city is not forced in the future to deliver PFAS-contaminated water.

Tucson Water has an operational target of no more than 18 parts per trillion of PFAS in its drinking water.

In 2018, both Tucson and the town of Marana filed suit against five companies that manufactured, marketed and sold a firefighting foam that contained the chemical compounds commonly known as PFCs, PFAs and PFOAs found in some area water wells. The lawsuit asks for unspecified damages to help clean up the contamination.

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The Air National Guard’s Tucson base stopped using the aqueous film-forming foam in fire trucks in December 2016 and in a base hangar in July 2018, a Guard spokesman told the Star in July.

This week, City Councilman Steve Kozachik wouldn’t rule out the possibility of going after other groups in addition to the companies named in the lawsuit.

“It’s time to do the same with the Department of Defense and the state because of the Arizona National Guard’s contribution to the problem, and Tucson Airport Authority,” he said.

An Arizona Air National Guard spokeswoman and a Tucson Airport Authority spokesman had no immediate comment Thursday.

While the contaminated water currently sits in an aquifer that the city is not using, Kozachik said. “The extremely high levels of PFCs we’ve found out by the Air National Guard are directly upstream from our central well field in midtown.

“While it’s not going to migrate downstream in the short term … we know the plume exists, and where it’s headed,” he said.

Contact reporter Joe Ferguson at jferguson@tucson.com or 573-4197. On Twitter: @JoeFerguson.