National Geographic : 2017 Jul
A RIVER At RIsk 149 In Linfen, a city on a tributary of the Yellow River, a residential development (top)—built to serve a robust mining industry—rises near farmland. In the 1970s this city was known for its clean water; by 2006 one study deemed it among the 10 most polluted cities in the world. Many miles upstream in Baiyin (left), a temple is visible above a limestone quarry. The previously rural area is now home to coal-fired power stations and plants that process nonferrous metals and chemicals.