Descriptions:
In October, the Hirose River, which flows through the city of Sendai, turned red and muddy, and an investigation by the city of Sendai and others found that the cause was natural iron rust. On October 30, the Hirose River, which flows through the Taihaku area of Sendai, was found to have a dirty red color over a wide area, and the city of Sendai and other relevant organizations began an investigation. As a result, silt deposits believed to be naturally occurring iron rust were discovered at a drainage site of rainwater and other substances discharged into the river in the Mukoyama 2-chome area of Taihaku District. Water quality tests showed iron levels were slightly above average, so the city of Sendai is investigating whether iron rust is the cause of the red turbidity. According to the Sendai city government, the outlet where the deposits were discovered was also connected to a cavity believed to be the remains of an abandoned lignite (a type of coal) mine. The red turbidity of the river has already disappeared and the city of Sendai says there is no danger to human health as no dead fish or other carcasses were found.