Sweetwater Authority reports stable PFAS results but intake-tower lab data delayed; staff to issue RFQ for treatment planning

The Sweetwater Authority Board of Directors heard an update on per- and polyfluoroalkyl substances (PFAS) in drinking water on April 23, with staff reporting April sampling similar to March and a running annual average for PFOA below state response levels.

The update came as the authority continues quarterly monitoring under the Unregulated Contaminant Monitoring Rule (UCMR5) and the state's new national primary drinking water standard implementation. Justin, a Sweetwater staff member presenting the item, said the authority is using UCMR5 laboratory results both to meet federal monitoring and to calculate compliance under the state framework. "A couple of weeks ago, we did present some updates on PFAS data," Justin told the board, adding that April results were "very similar to what we sampled a few weeks prior in March." He noted that laboratory reprocessing can change reported values and that some results shown as "not detected" on first reporting can appear as small positive values after reprocessing.

Why it matters: PFAS are a class of persistent chemicals that have drawn health limits from federal and state regulators. The authority is required to monitor and report under UCMR5 and to track compliance with California response levels and the new national standard.

Key details

- PFOA: Staff said a January 14 sample had been above California's response level for PFOA (10 parts per trillion) on a single sample; when averaged in the required running annual average the board was shown a value of 6.7 parts per trillion so far, below the response level. Justin explained how the quarterly running annual average is computed and said a July quarter-4 sample will complete the first annual calculation window.

- PFOS and other analytes: Justin said the March-to-April comparison shows generally similar measurements, indicating the transferred water likely mixed into the reservoir. He cautioned that some March results originally reported as "not detected" moved to low positive numbers after laboratory reprocessing for reporting purposes.

- Intake-tower samples delayed: During public comment, Karen Henry asked about data from the intake tower collected under the statewide PFAS monitoring order issued Jan. 16, 2025. Justin said the intake-tower samples had been run by the contract laboratory but that the lab returned them with quality-control problems. "We have not received an acceptable report back from the contract laboratory," he said, explaining lab staff and Sweetwater staff are meeting the following week with the laboratory's organics expert to resolve humic/fulvic interference and get valid results.

- Next steps: Staff said they are preparing a request-for-qualifications (RFQ) to retain an engineering consultant to scope treatment options, timelines and costs. Director Cox asked for a timeline for the RFQ and staff responded they will bring a more detailed schedule at the next opportunity.

Public questions and board reaction

During the public-comment period Marina asked about rebates or bill credits for home filtration systems; staff said the board could not respond during public comment but that staff would speak with her after the meeting. Karen Henry pressed for intake-tower results; Justin confirmed the samples exist but the laboratory's report currently has QC issues and the authority is working with the lab to obtain valid data.

The board asked about near-term sampling and compliance. Justin confirmed the authority will supply the quarter-4 sample data when available and that the monitoring results are being used for both UCMR5 reporting and state compliance calculations.

Outlook

Staff said the April data do not materially change the authority's public position: they will continue the mandated monitoring, re-run laboratory reporting as needed, finish the first-year compliance calculation after quarter 4 sampling, and move forward with procurement of engineering support for potential treatment planning. Justin said, "we are in the process of developing the RFQ at this time," and that staff will return with a detailed schedule at the next meeting.

Ending note: This was an information item; the board took no formal action. The authority will report any validated intake-tower data and updates from the RFQ process at future meetings.