California Seeks Action to Better Understand PFAS Discharge in Publicly Owned Treatment Works

Posted on Behalf of  Andrey Massarsky

The California State Water Resources Control Board (State Water Board) recently released an investigative order (WQ 2020-00150-DWQ) requiring the sampling and analysis of per- and polyfluoroalkyl substances (PFAS) at publicly owned treatment works (POTWs) in California that have a design capacity at or exceeding one million gallons of wastewater per day. The State Water Board determined that 259 POTWs throughout California were subject to this order. These specific POTWs are required to submit a variety of information to the State Water Board regarding their PFAS sampling event findings. Numerous scientific studies from the last 10 years have shown that exposure to PFAS can lead to adverse ecological impacts.

There are known to be nearly 5,000 individual PFAS (FDA, 2020). Current laboratory analytical methods are unable to reliably detect many of these compounds in environmental samples. As a result, this order noted 31 specific PFAS that must be measured (Table 1) and outlined the specific testing and reporting requirements for a mandatory 1-year sampling period at each POTW. This order requires samples to be collected from multiple water media (influent, effluent, reverse osmosis concentrate/retentate, and groundwater) as well as biosolids. The first quarterly sampling event required under this order must be completed by December 31, 2020 (unless a written, site-specific extension was granted by the State Water Board). Analytical results from each mandatory sampling event must be uploaded to the Water Board’s GeoTracker system ( within 30 days of receiving the laboratory analytical report. This order is part of a statewide effort to evaluate the effect of PFAS-containing wastewater on groundwater and surface water PFAS concentrations. Specifically, the collected data will be used for a preliminary investigation of the mass loading of PFAS into POTWs and discharged from POTWs in different media, including treated wastewater, brine, and biosolids. Importantly, failure to comply with the order may subject a POTW to civil liability of up to $10,000 per day for each day in which the violation occurs (State Water Board, 2020).

According to the order, the discharge of PFAS-containing effluent can affect water quality if the effluent is discharged directly to surface waters or allowed to percolate to groundwater. Application of PFAS-containing biosolids can also affect water quality, since certain PFAS may percolate to groundwater or be carried to surface water via irrigation or stormwater (State Water Board, 2020). Certain PFAS on the list also have the potential to bioaccumulate in aquatic food webs. While the State Water Board order does not outline a detailed scientific rationale, the order is supported by the scientific literature, which indicates that certain PFAS have been 1) detected in wastewater effluent (e.g., Houtz et al., 2016), 2) continuously discharged into the environment from point sources (e.g., sewage treatment plant) (Ahrens and Bundschuh, 2014), and 3) shown to accumulate in oceans (e.g., Casal et al., 2017; Gonzalez-Gaya et al., 2019), freshwater bodies (e.g., Murray and Salim, 2019), and aquatic species (e.g., Casal et al., 2017; Fair et al., 2019).

Table 1. List of 31 PFAS Requiring Sampling and Analysis at California POTWs

Cardno scientists have extensive professional experience conducting ecotoxicological and human risk assessments for various chemicals, including PFAS, as well as expertise in environmental health and the management and remediation of contaminated sites. For more information on Cardno's capabilities, please contact Paul Scott ( or Scott Duzan (