No sooner had the EPA established the Superfund program in 1980 to clean up the nation s toxic waste dumps and other abandoned hazardous waste sites, than a little Montana town found itself topping the new program s National Priority List. Milltown, a place too small to warrant a listing in the U.S. Census, sat alongside a modest hydroelectric dam at the confluence of the Clark Fork and Blackfoot Rivers. For three-quarters of a century, arsenic-laced waste from some of the world s largest copper-mining operations had accumulated behind the dam. Soon, Milltown became the site of Superfund...