La Oroya is a city of about 33,000 people on the River Mantaro in central Peru. It is situated on the Altiplano some 176 km east-north-east of the national capital, Lima, and is capital of the Yauli Province. La Oroya is the location of a smelting operation that earned the town a place on the Blacksmith Institute's 2007 report, "The World's Worst Polluted Places".