After getting PFAS levels as low as 2 ppt in April, levels have increased in Ann Arbor, Mich., leaving city officials searching for potential sources of contamination.
Levels of toxic per- and polyfluoroalkyl substances(PFAS) chemicals found in Ann Arbor, Mich., drinking water have increased.
After managing to get PFAS levels as low as 2 ppt in April, PFAS detections in the river water were around 40 ppt in October, reported MLive. Treated water delivered to customers ranged from 25 to 29 ppt, city test results show.
There were five types of PFAS detected. Two of the five meet state standards and there are no limits in place for the other three. The two types found in Ann Arbor’s drinking water last month that are on the proposed regulation list are PFBS and PFHxA, which have proposed limits of 420 ppt and 400,000 ppt, respectively.
Most of Ann Arbor’s drinking water comes from Barton Pond on the Huron River, which is contaminated with PFAS from upstream pollution.
“The amount of PFAS our filters remove is dependent on the concentration coming in, the type of PFAS, and the age of the carbon in the filters,” said Brian Steglitz, water plant manager. “We replaced approximately 60% of the carbon in filters in March and April, so it is expected that PFAS removal was high in the first few months after replacement.”
October tests showed seven types of PFAS in the raw river water.
Tribar Manufacturing was identified as a major source of contamination last year, but the search for other potential contributors to the contamination is ongoing, reported MLive. Tribar has put filters in place to reduce discharges, but there may be residual contamination coming from sewer pipes between Tribar and the Wixom wastewater plant.
“Ann Arbor is so far a best-case scenario for how you get on top of a problem, manage a problem and reduce contaminants, but there are systemic things that need to change,” said Daniel Brown, a watershed planner with the nonprofit Huron River Watershed Council.