In May 2014, drinking water wells that supply the Pease International Tradeport were sampled. The Haven Well, one of three wells that serves the Tradeport and the New Hampshire Air National Guard Base at Pease, showed elevated levels of the unregulated contaminant perfluorooctane sulfonic acid (PFOS). How long PFOS may have been present in this well is not clear. Because the level of PFOS exceeded the “provisional health advisory” set by the U.S. Environmental Protection Agency (EPA), the well was shut down by the City of Portsmouth on May 12, 2014, and since that time has been physically disconnected from the system.  Based on information ATSDR has reviewed, drinking water on the Tradeport currently meets all federal and state guidelines for PFAS in drinking water. ATSDR recommends that community members become familiar with water quality reports that can be found on the City of Portsmouth’s website.