CBSE Class 9 Answered

Three causes of the river water pollution are

1. Increase in population and urban settlements have polluted the rivers. Large amount of domestic, municipal and agricultural wastes are disposed off in the rivers.

2. Huge quantities of untreated sewage and industrial effluents are disposed in rivers which not only diminishes the quality of water but also the self-cleansing capacity of the river.

3. Dumping of used oil and paints into river water has also polluted the river.