River Pollution - Yahagigawa River, Aichi Prefecture, Seto Inland Sea - May 1998

River Pollution - Yahagigawa River, Aichi Prefecture, Seto Inland Sea - May 1998

In May 1998, pollution is progressing in rivers throughout Japan, with particularly serious conditions reported in rivers adjacent to industrial areas. In the Yahagi River in Aichi Prefecture, water pollution was caused by cadmium and lead in wastewater discharged by a company engaged in metal smelting. There are concerns about the health hazards to nearby residents and the impact on agricultural crops. In this area, major companies, notably Sumitomo Metal Mining, are believed to be involved, and demands for environmental improvement by local residents are increasing.

Furthermore, in rivers flowing into the Seto Inland Sea, PCBs (polychlorinated biphenyls) emitted from chemical plants have accumulated in fish and shellfish, adversely affecting the entire ecosystem. In areas where chemical companies such as Mitsui Chemicals and Showa Denko operate, PCBs have remained in the environment for many years, resulting in increased pollution of rivers and coastal areas.

In urban areas, domestic wastewater is also a major source of river pollution. For example, in the Arakawa River in Tokyo, wastewater from households and commercial facilities flows into the river without sewage treatment, resulting in BOD (biochemical oxygen demand) values far exceeding the standard values and leading to eutrophication. This has led to massive algae blooms and frequent mass fish kills due to acid deprivation.

Since 1998, the government has been implementing a nationwide water quality improvement plan, upgrading sewage treatment facilities and tightening effluent regulations. In the Seto Inland Sea region in particular, regulations have been tightened for industrial effluent and effluent standards have been set more strictly, but illegal discharges and improper treatment continue to be a problem.