"BUTTE, Mont. — High above this storied copper town, one of the tallest earth-filled dams in the country holds back more than 6.5 trillion gallons of toxic sludge from an open-pit mine.

The dam is set to grow even taller. Yet it is the least of Butte’s immediate concerns.

Residents have been waiting years to learn how the Environmental Protection Agency will finish cleaning up a different part of mining’s legacy here — the cavernous Berkeley Pit, now a mile-long, 900-foot-deep poison lake, and a vast network of contaminated subterranean tunnels. Together they constitute the nation’s largest Superfund complex. State and federal officials and the company on the hook for cleanup have negotiated privately; the outcome may be revealed within weeks, if not days."

Kathleen McLaughlin reports for the Washington Post February 10, 2020. [2]