World's Nastiest Lakes and Rivers (Slideshow)

Image via: Getty Images - ChinaFoto Press

Before you go dipping your toes in the first lake or river you come across this summer, make sure it's not on our list of the world's dirtiest lakes and rivers.

More on improving water quality after the jump.We've scoured the globe to find out just which rivers are full of metals, agricultural runoff, dead zones and even, gasp, sewage! In this slide show we've captured images of some of the worst offenders and put them on display so you can stay healthy and safe this summer season.

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