The search for a source of PFAS contamination spreading in the Huron River across five Southeast Michigan counties points to Wixom, where city officials told the state in June that its wastewater treatment plant has been sending contaminated water into a tributary.

Test results from June 14 show that one version of the "forever chemicals" was found in effluent at 24 times the allowed amount in Michigan's surface waters.

The discovery comes as the state seeks tests from 95 municipal wastewater treatment plants with significant industrial processing. The goal: to determine whether plants are receiving PFAS pollution in influent, and discharging it into lakes and rivers where, in turn, the chemicals are getting into Michigan's drinking water systems.

Cities like Ann Arbor, Grayling, New Baltimore and East Tawas have reported the contaminant in their finished water at levels below the federal health advisory. Parchment, near Kalamazoo, learned this summer its levels were far above that number, prompting an emergency shut-down of the system.

It also comes as the state investigates PFAS contamination across the five-county Huron River Watershed that escalated Friday into a widespread "do not eat" fish advisory and signaled heightened concern about the chemical levels in southeast Michigan.

PFAS represents a group of water-repellent chemicals known as per- and poly-flourinated compounds, which have links to cancer, liver damage, birth defects and autoimmune diseases.

According to a letter sent Aug. 6 from the Michigan Department of Environmental Quality to the operator in charge of the Wixom wastewater treatment plant, PFOS at 290 parts per trillion (ppt) was measured in water discharged into Norton Creek in southwest Oakland County. The state allows up to 12 ppt.

The cause, according to documents obtained under the Michigan Freedom of Information Act by MLive.com, is an industrial plating facility. Test results sent to the city show that one of two Adept Plastic Finishing Inc. factories in Wixom sent high levels of the contaminant into the wastewater treatment plant. Documents of water testing at Adept's Plant 4 show a PFOS reading of 28,000 during a mid-May test. Adept received the results on June 19.

Meanwhile, the city had its effluent tested on June 14, with results reported to Wixom officials on June 25. In addition to the PFOS at 290 ppt, testing also showed the water was above recommended limits of 2 ppt for seven other PFAS chemicals. Among them were PFOA (9.7 ppt), PFHbA (380 ppt) and PFBA (180 ppt).

The city notified the MDEQ of those results on June 27, according to documents. It also is investigating the possible roles of other businesses in those totals and the totals for PFAS precursor chemicals.

Wixom City Manager Steven Brown did not respond to requests for comment on the test results.

"(W)e likely receive wastewater containing these substances from one or more customers," Brown said in an email that neither addressed specifics of the city's PFAS findings nor the city's actions since learning about the contamination flowing through its facility.

"(W)e have been sampling our wastewater treatment plant discharge, or effluent, to determine the level of these substances," he wrote. "We plan to continue to cooperate with MDEQ on this matter and be in compliance as regulations on these substances are modified and/or issued. "

Unclear is how long the contamination has been taking place, how high it may have reached and when the flow of PFOS into the wastewater treatment plant - followed by discharge into Norton Creek - will cease.

Adept representatives did not reply to requests for comment.

Adept manufactures chrome-plated plastics, including vehicle badges for the auto industry, and it operates two plants in Wixom. According to information submitted to the city by the company, Adept stopped using a PFOS-containing surfactant in 2015.

"To our knowledge there are no PFAS or PFOS chemistry in our building at this time," Adept told the city as Wixom staff sought to fulfill state requirements for identifying potential PFAS coming into its system.

So far, the MDEQ met with the city and what it called "their confirmed source" after issuing the letter about compliance. It's also working with the U.S. Environmental Protection Agency on the test results.

Those tests, said MDEQ spokesperson Scott Dean, will aid the state as it examines "some of the larger questions, such as whether the PFOS we are finding is residual from previous use (years ago) or if current chemical(s) ... either contain PFOS or precursors to PFOS that may break down during industrial processes."

The city must test its effluent monthly, according to the letter from the DEQ.

It continued: "Please know that although the DEQ ... expects to see ongoing progress, we understand that reduction of PFOS may take time, given the complexity of the issues and the emerging nature of this pollutant."

Meanwhile, the letter from the DEQ to Wixom was sent two days after the state issued a "Do not eat" advisory for fish downstream of Norton Creek, starting at Kent Lake in Kensington Metropark and extending along portions of the Huron River through Livingston County and northern Washtenaw County.

That warning was expanded twice, with the most recent advisory on Aug. 31 calling for people to avoid eating all fish from the Huron River, from Oakland County to Lake Erie. The full watershed covers 910 square miles.

Dean said the state has not yet identified the boundaries for the contamination.

So far, the state can't say the contamination originating in Wixom is responsible for the PFAS found in the fish, which had been taken from the water in 2017 and tested this summer at three to four times the maximum health limit.

"This is a question we're actively trying to answer," Dean said.

Identifying one source of the pollution offers hope for cleaning PFAS from the river, said Laura Rubin, executive director of the Huron River Watershed Council.

But it also makes the ongoing situation in the watershed frustrating, she said.

“This seems the result of us having weak enforcement protocol,” Rubin said. “And, along with that, weak rules on how we ... allow toxic chemicals and pollution to come into our manufacturing processes.”