Top:  Illustration of a short-chain PFAS compound with 6 or fewer carbon molecules, represented above by the grey circles.

On September 1, 2025, the Minnesota Pollution Control Agency (MPCA) began requiring all wastewater treatment facilities (WWTF) intending to apply biosolids to agricultural land or used for reclamation projects to collect at least one representative sample of their biosolids and test it for per- and polyfluoroalkyl substances (PFAS) each year using draft EPA Method 1633A. The results from this sample must be received prior to biosolids being applied to land. “We expect that most biosolids will have low amounts of PFAS,” stated MPCA in a Biosolids PFAS Strategy Fact Sheet. “However, in other states where biosolids have been tested for PFAS a small number of samples showed elevated levels. The high levels were due to discharges from an industry that used PFAS in its process. In these cases, reducing the source of PFAS from the industry lowered the amount of PFAS in the biosolids.” MPCA created four tiers of action steps based on the analyses of the samples. For example, Tier 1 is for samples that contain ≤20 µg/kg PFOA or PFOS measured in the biosolids. The action step is to notify the landowner and farmer that PFAS results are available on request.