Cases at a local level : Japan
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Cases Japan


Case Overview

Minamata Bay

  • The Minamata Bay is an inner bay facing the Yatsushiro Ocean (Shiranui Sea) in Kyushu.
  • In 1932, the factory started to operate the acetaldehyde compound acetic acid facilities using mercury as a catalyst. Contaminants from the factory, especially methyl mercury turned Minamata Bay into a sea of death.
  • It took many years for people to realize the problem and to understand the causes. During this time, many victims suffered a pollution-induced disease.
  • In 1956, an official recognition of Minamata Disease was first issued. After that, the facilities suspended the operation, and a dredging and sludge disposal program was implemented
  • Presently the mercury pollution, which was the origin of the environmental pollution, is coming to the end, but many problems still need to be studied.

Lake Kasumigaura

  • Lake Kasumigaura is located in the northeast of Tokyo and the southeast of Ibaraki Prefecture, and it is Japan’s second largest natural freshwater lake.
  • Due to natural factors such as the large water volume to lake area ratio, the lake was particularly prone to eutrophication. From about 1965, as various activities in the Kasumigaura basin began to flourish and water use expanded the quality of Kasumigaura’s water began to change along with growing concern about the water quality.
  • Several measures against the pollution of Lake Kasumigaura were taken by the enforcement of the Ordinance to Prevent Eutrophication. Among them were regulations of factory drainage, construction of sewage systems, skimming of water bloom “Aoko”(algae), and dredging of bottom sludge.
  • Thereafter, the COD gradually decreased. However, for further water quality improvement, we need to push a pollutant load reduction measure more on every pollution source, address the pollution from non-point sources, and restore sound ecosystems. We must also consider new concepts for management of the lake and the entire Kasumigaura basin including the land use planning, total quantitative regulations considering the capacity of the environment to absorb pollutants, and the creation of regional recycling systems to protect our environments.