The latest testing on Rhinelander’s Municipal Well 7 showed no detection of the two best-known per- and polyfluoroalkyl substances (PFAS) chemicals.
In June, the city shut off Well 7 after the combined PFOA and PFOS levels exceeded both federal and state recommendations for the compounds, which have been linked to health problems.
Since then, the city has been drawing drinking water for residents from its other active wells.
Because of the latest low PFAS levels in Well 7, Rhinelander City Administrator Daniel Guild raised the possibility of inaccurate original results.
“This has raised several questions about the both the accuracy and veracity of the original sample which the detect was previously discovered. Remember these detections were incredibly small, in the range of trillioneths [sic], making sample contamination a theoritical [sic] possibility,” Guild wrote in a Tuesday-night message to city residents.
In the same message, Guild highlighted the city’s actions on PFAS since this summer, including communicating with water experts, continued testing, and the creation of an online portal for PFAS information. He also mentioned future steps the city is exploring, including a citizen’s water academy.
In late June, the city shut down Well 7, which is located at the Rhinelander-Oneida County Airport, after the combined levels of PFOA and PFOS tested at 104.8 parts per trillion (ppt).
There are no enforceable federal or state regulations for combined PFOA and PFOS levels in drinking water. But the federal Environmental Protection Agency recommends levels not exceed 70 ppt. Wisconsin’s Department of Health Services has set an even more restrictive recommendation at 20 ppt. The state is working on making those recommendations into enforceable regulations. Other states already have PFAS laws on the books.
A second test of Well 7 on June 27 showed the combined PFOA and PFOS level had fallen to 86.9 ppt.
A WXPR open records request showed PFOA and PFOS levels continued to drop in Well 7 during subsequent testing:
- May 30, 2019 sample: 104.8 combined PFOA and PFOS
- June 27, 2019 sample: 86.9 combined PFOA and PFOS
- July 24, 2019 sample: 26.1 combined PFOA and PFOS
- August 27, 2019 sample: 5.82 combined PFOA and PFOS
- October 2, 2019 sample: no detection of PFOA or PFOS
Despite the improving test levels, Well 7 has not been active at any time since late June, when it was initially turned off. In an email, Guild wrote it would not be activated without prior notification of water customers.