Which human activity has the most negative effect on the stability of a river environment

Pouring the industrial and community wastes into the rivers has had a most significant negative effect on the stability of river environment. This leads to a decrease in the available oxygen for the marine creatures, and they die. The plastics that is dumped into the water are eaten by the aquatic animals, which ultimately leads to their death. The release of toxic materials into water has destabilized many water bodies.