An ink manufacturing plant in Shenzhen is suspected of malpractice after red fluid was found directly below the overflow of a local reservoir on April 16.
The Tiegang Reservoir is the biggest reservoir in the city of Shenzhen with a capacity of 49 million cubic meters of water.
The pollution was spotted by a patrolman, and cleanup work began immediately after the news was reported.
The water to the west of the floodgate was deep red on the surface, and the area to the south was also affected.
Some local residents thought the coloring was due to blood.