Citarum River, Indonesia
The Citarum is the third longest river in Java, but it has been called the world's most polluted river — and for good reason. While the debris on top of the water is the most visible sign of a problem, what lies under the surface is the bigger problem. The 5 million people who live in the river basin are directly affected, but around 30 million people rely on the river in some form for drinking, bathing or agricultural use.
The Guardian sums up the situation well: "Over 200 textile factories line the river banks. The dyes and chemicals used in the industrial process — lead, arsenic and mercury amongst them — are churned into the water, changing its color and lending the area an acrid odor."