An advocacy group is challenging a permit for Manchester’s wastewater treatment system that state regulators approved in May, saying the system could be releasing levels of PFAS chemicals into the Merrimack River that go against state standards.

In an appeal filed by the Conservation Law Foundation, lawyers say New Hampshire’s Department of Environmental Services did not consider whether the wastewater facility’s permit complied with a state standard meant to protect fish, and the people who eat them, from toxic chemicals.

While the federal Environmental Protection Agency was considering the permit, the Foundation asked them to include stronger limitations on PFAS chemicals entering the plant from industrial sources and on the chemicals coming out of the plant.

In the permit issued by the EPA and approved by New Hampshire officials, the plant is required to test for PFAS and report the levels of those chemicals coming in and going out in the effluent they discharge into the Merrimack River. It also requires testing of the levels in sludge — the solids that are separated out from wastewater and, at the Manchester plant, burned in an incinerator.

“The purpose of this monitoring and reporting requirement is to better understand potential discharges of PFAS from this facility and to inform future permitting decisions, including the potential development of water quality-based effluent limits on a facility specific basis,” federal regulators said in a fact sheet about the permit.

There’s no current requirement to limit PFAS that comes out of the facility. Jillian Aicher, a fellow at the Conservation Law Foundation, said that’s a problem.

“People in Manchester and in surrounding communities deserve clean water,” she said. “Clean, fishable and swimmable water is what the Clean Water Act and New Hampshire state standards call for.”

In their appeal, the Conservation Law Foundation says when state officials approved that permit, they considered the state’s numerical PFAS standards but ignored a “narrative” standard that says surface waters, like the Merrimack River, must be free from toxic substances that injure animals, fish and humans or accumulate in edible aquatic life.

Aicher says she’d also like to see the City of Manchester regulate industrial sources that contribute to the accumulation of PFAS chemicals in the wastewater treatment system.

The Manchester wastewater treatment plant, like others across the state, collects the PFAS chemicals that are widely present in the environment. They don’t add PFAS to the wastewater, but they process it in a way that changes the chemicals that are already there. That means wastewater exiting the facility can test higher for PFAS than the wastewater entering the facility.

Manchester’s plant receives hundreds of thousands of gallons of wastewater per day from industries that have historically been connected with PFAS contamination, including manufacturers, cleaning companies, and hospitals. It also processes landfill leachate, which has in some cases been found to have high levels of PFAS.

New Hampshire Senior Assistant Attorney General Christopher Aslin said the New Hampshire Department of Justice was reviewing the appeal and would represent the state’s Department of Environmental Services in the case.

The City of Manchester did not respond to requests for comment.