Suspected contamination source: Firefighting foam used at San Luis Obispo (SLO) Regional Airport (McGuinness, 2016)
A well owner reported his water had “chemical” smell. PFOS and PFOA were found during the EPAs Third Unregulated Contaminant Monitoring Rule (UMCR3), which took place from 2013-2015. EPA stated 99% of samples from SLO were below EPA’s public health advisory level (PHA) level*. One Atascadero well was equal to EPA PHA for PFOA. Levels are unknown for private wells.
In September 2016, California’s Office of Environmental Health Hazard Assessment (OEHHA) filed public notice of intent to list perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) as known to the state to cause reproductive toxicity under the Safe Drinking Water and Toxic Enforcement Act of 1986. The public comment period closed in December 2016 and final listing as a reproductive toxicant is expected at a later date.
*The PHA is the old one. EPA PHA was lowered from a standard of 200 ppt for PFOS along with the previously noted level of 400 ppt for PFOA. The PHA levels were lowered to a combined PFOA/PFOS level of 70 ppt 2016. It is unknown how many wells are effected under these new guideline).