For 500 years, the Bolivian Andes have been heavily mined. Today, the water that seeps out of them is nasty stuff. It's tainted red with iron and laden with toxic metals such as cadmium that pollute rivers for hundreds of miles. The water can be so poisonous that, over time, it destroys the livers and kidneys of area residents. In Bolivia, expensive high-tech solutions aren't an option. So how to clean up the waterways on a shoestring budget? Add llama dung.