SENDAI, Oct 31 (News On Japan) - The Hirose River in Sendai City has turned a mysterious red, sparking local concern. Residents are puzzled, with some noting they've never seen anything like it before.
Recent aerial surveys and investigations by Miyagi Prefecture have yet to identify the source of the discoloration, though a similar incident in 2010 was caused by rust flushed from stormwater pipes after heavy rain. In another recent case in Yokohama, red discoloration was linked to "red tide" caused by plankton. The exact cause in Sendai, however, remains unknown.
Source: ANN