For nearly 100 years, a Montana dam held back 6.6 million cubic yards of contaminated mining sediment; its removal helped reconnect two rivers and restore the landscape

For decades, the meeting point of the Clark Fork and Blackfoot rivers in western Montana lay behind a dam that held back more than water. Sediment carried downstream from copper mining around Butte had accumulated in the reservoir, leaving a legacy of contamination that reached beyond the river itself.