PFCs in Drinking Water

Keeping your water safe from PFCs
What are PFCs and how are they regulated? 

PFCs are perfluorinated chemicals, a term scientists use for a group of chemicals that include PFOS (Perfluoro-octanesulfonic acid) and PFOA (Perfluorooctanoic acid). These compounds are not currently regulated by the U.S. Environmental Protection Agency (EPA) and are not found naturally in the environment. The EPA uses the Unregulated Contaminant Monitoring Rule (UCMR) to collect data for substances that may be present in drinking water but do not yet have health-based standards set under the Safe Drinking Water Act (SDWA).

Here’s what we know. 

In May of 2016, minute amounts of PFOS were detected in three of our wells in the Lower Issaquah Valley Aquifer (LIVA). At that time, the level of PFOS detected was 19 parts per trillion (ppt), which was far below EPA’s health advisory level of 70 ppt. This appearance of PFCs in the aquifer has since been attributed to the use of firefighting foam after analysis of soil samples. At this time, only the Plateau Zone is affected, not the Cascade View Zone.

What we've done to protect your water. 

With the help of expert consultants, the District conducted extensive research and developed a three-dimensional groundwater model to assess how PFCs travel through the water underground. Based on what we learned from the groundwater model, we changed our point of withdrawal to a well that is furthest from the potential plume migration. Latest test results have confirmed that this shift in water production, coupled with the blending of groundwater from our wells with water from the Seattle Public Utilities’ south regional water connection has brought PFCs in drinking water down to non-detect levels that are less than 2.5 ppt…even further below EPA health advisory levels. These results have confirmed and validated the District’s groundwater model forecasts.

The Board of Commissioners also adopted an interim Monitoring and Response Plan for Perfluorinated Compounds that contains recommended actions to reduce the likelihood of any future increases in PFC concentrations, as well as options to protect water quality provided to customers if PFC concentrations do increase.

Here's what we're continuing to do. 

Clean water is our highest priority. We are continuing to maintain a vigorous water quality testing and analysis protocol that exceeds EPA and Department of Health (DOH) requirements. Commissioners and District leadership are working closely with DOH, the City of Issaquah, Eastside Fire and Rescue, and the Washington Department of Ecology (DOE) to better understand the source of PFCs and create plans for mitigation. As part of this intergovernmental working group, the DOE is conducting a study to identify and further evaluate possible sources of PFCs in the aquifer. Once the study is completed, the DOE will be providing an action plan regarding the PFCs.

Separately, the DOH is finishing a statewide survey of sites where there may have been a high likelihood of the use of products containing PFCs such as military installations, manufacturing plants, and fire training sites. Based on the results of this survey, the DOH will be setting regulatory guidelines over the next year or two, which may include adjusting the current EPA health advisory level.