Depletion of oxygen in water:
The process by which a body of water becomes rich in dissolved nutrients from fertilizers or sewage, thereby encouraging the growth and decomposition of oxygen-depleting plant life and resulting in harm to other organisms.
If they keep dumping so much sewage water in the river, eutrophication will be so bad that you won't be able to see through the algea.
Eutrophication = bad
Def by Juliette