The Kasai River is the tributary of the Congo River located in Central Africa. It originates at the central Angola and flows eastwards to reach the border between Angola and the Democratic Republic of Congo, where it turns northwards and serve as border until it flows into the DRC. It is the second longest African river after the Nile.
The pollution of the Kasai River resulted in the deaths of 12 people and thousands becoming ill. The source of the pollution was traced to the toxic waste produced by an Angolan factory that specializes in industrial diamond mining.