Water districts remain vigilant amid new rules

Marin County's main water districts have not detected hazardous chemicals in the water supply, but will continue testing following new federal regulations.

The Biden administration this month set strict limits on specific “forever chemicals” — such as toxic PFAS, or perfluoroalkyl and polyfluoroalkyl substances that make items resistant to stains, heat and water — in drinking water.

The new rules were expected, said representatives with Marin Municipal Water District and the North Marin Water District. Both utilities said they will continue to testing and remain unconcerned about future contamination.

The new regulation requires utilities that supply drinking water to reduce two common PFAS to no more than 4 parts per trillion. The rules, set by the Environmental Protection Agency, state that utilities will have three years to test for the chemicals, and two additional years to filter them out, if found.

Tony Williams, general manager for the North Marin Water District, said the district has been following the issue for years. He said Stafford Lake reservoir was tested in November 2023 in advance of the new regulations. The results were negative for 29 PFAS compounds — including for the five included in the new standards.

“So that is good news for us,” Williams said. “New testing will be performed, essentially repeating what was done in November 2023, starting this year, but we don't expect the test results to be different.”

Adriane Mertens, a spokesperson for Marin Municipal Water District, has been watching the EPA's efforts throughout the rule-making process in anticipation of the new requirements.

Previously, MMWD completed a round of testing in December 2020 in which samples were taken at each of its treatment plants: Bon Tempe, San Geronimo and Ignacio Water Quality Station, as well as a number of locations throughout the distribution system. None of the chemicals were detected.

“To date, Marin Water has not found concentrations in the water delivered to our community above the maximum contaminant levels set by the EPA on April 10, 2024,” Mertens said.

The federal regulations require yearly testing. Mertens said she does not expect different results due to careful watershed protections. She said PFAS are commonly found in water sources downstream of potential industrial contamination, groundwater, or areas where there were historically major fires.

“We are fortunate in Marin that the source of our reservoir water is not susceptible to PFAS contamination,” she said.