River Pollution - Yahagi River, Aichi Prefecture & Seto Inland Sea - May 1998

River Pollution - Yahagi River, Aichi Prefecture & Seto Inland Sea - May 1998

In May 1998, river pollution across Japan was becoming a serious issue, particularly in rivers adjacent to industrial areas. In the Yahagi River, Aichi Prefecture, water pollution caused by cadmium and lead discharged by metal refining companies raised concerns about health effects on nearby residents and damage to crops. Sumitomo Metal Mining, a major company, is believed to be involved, prompting demands for environmental improvements from local communities.

Additionally, rivers flowing into the Seto Inland Sea have been contaminated by PCBs (Polychlorinated Biphenyls) discharged from chemical plants, leading to bioaccumulation in marine life and affecting entire ecosystems. In regions where companies like Mitsui Chemicals and Showa Denko operate, PCB residues have persisted in the environment for years, causing expanding contamination in rivers and coastal areas.

In urban areas, household wastewater is a major contributor to river pollution. For example, in the Arakawa River in Tokyo, wastewater from households and commercial facilities has been discharged without proper sewage treatment, causing BOD (Biochemical Oxygen Demand) levels to exceed legal standards, leading to eutrophication. Algal blooms have increased, and mass fish deaths from oxygen depletion have become common.

Since 1998, the government has been implementing a nationwide water quality improvement plan, improving sewage treatment facilities, and tightening discharge regulations. In the Seto Inland Sea area, stricter industrial wastewater regulations have been implemented, but illegal discharges and improper treatment remain pressing issues.