But the market for silver collapsed during the Great Depression and didn't recover until the start of World War II, when minerals were needed for the war effort. While North Idaho's silver-lead mining created fabulous fortunes and employed many miners, it also created one of the nation's largest Superfund sites. Heavy metals washed down the Coeur d'Alene River and into Lake Coeur d'Alene. Hecla reached a $263 million settlement for cleanup of historic mine waste with the federal government and the Coeur d'Alene Tribe in 2011. The company made the last settlement payment in 2014. Over the years, Hecla developed a worldwide reputation for expertise in deep, underground mining. That work continues at the company's flagship Lucky Friday Mine in Mullan, Idaho, where Hecla is sinking a new shaft, Baker said. The shaft will extend 10,000 feet below the earth's surface to access new ore bodies.