Yokosuka mayor calls for investigation into water contamination at U.S. base

Yomiuri Shimbun file photo
Yokosuka Mayor Katsuaki Kamiji speaks at the Yokosuka city office in January 2021.

YOKOSUKA, Kanagawa — Yokosuka Mayor Katsuaki Kamiji has asked the commander of U.S. Naval Forces Japan to conduct an immediate investigation following the detection of a harmful substance at a level exceeding the limit imposed by the Japanese government in wastewater from a treatment plant at the U.S. Navy’s Yokosuka base in Kanagawa Prefecture.

Perfluorooctane sulfonic acid (PFOS), a toxic substance that is harmful to humans, was detected at the wastewater plant.

Less than 50 nanograms of PFOS per liter of wastewater is permitted under Japanese standards. Levels exceeding 100 times that amount were detected at the base’s wastewater treatment plant, according to a recent analysis conducted by the U.S. side.

During a visit to the base on Thursday, Kamiji told Rear Adm. Carl Lahti the incident had severely damaged the relationship of trust, and he urged the commander of U.S. Naval Forces Japan to identify the cause and implement preventive measures.

The mayor also asked for the discharge of wastewater to be suspended until filters that can absorb the compound are installed at the facility.

Lahti apologized for causing anxiety among local residents but claimed it would be impossible to stop discharging wastewater because base residents would have to be relocated. He said filters would be installed as soon as possible and asked for public understanding.