Kumamoto: New Sluice Gates Installed at Site of Methylmercury Poisoning Which Caused Minamata Disease

The Yomiuri Shimbun

14:03 JST, May 3, 2025

MINAMATA, Kumamoto — New sluice gates have been installed at a drain in Minamata, Kumamoto Prefecture, where toxic industrial wastewater was once discharged, causing residents to develop a serious neurological disorder known as Minamata disease.

Minamata disease was one of the four major industrial pollution disasters in Japan during the mid-20th century. A chemical manufacturer in the city discharged wastewater containing methylmercury into the sea.

After consuming contaminated seafood, people developed symptoms of poisoning, such as immobility and loss of the senses of taste and touch. Industrial wastewater containing methylmercury was discharged from the drain from 1932 to 1968.

The city government announced in 2023 that it was removing the sluice gates due to aging, but many people called for their preservation as historical artifacts. It later decided to remove the old gates and install duplicates.

The new gates, made of Kumamoto-produced cypress, are about 3 meters high and 2.4 meters wide. They were installed with a crane on April 11.

“This is the origin of Minamata disease. I’m glad we were able to preserve this place so that we can pass on its history forever,” said a Minamata disease patient, 61, who was observing the work at the site.