Montana

Berkeley Pit is a former open-pit copper mine, located in Butte, Montana. It is 1.6 km (1 mile) long, over 0.8 km (0.5 mile) wide and 542.5 meter (1780 feet) deep, where 274 meter (900 feet) is full of extremely toxic water. From the surface it looks like its filled with blood, but the water is highly saturated with copper to the point that miners is able to harvest the metal from the water.

The toxic water also contains chemicals comprising arsenic, cadmium, zinc and sulfuric acid. In 1995 a flock of migrating geese landed on Berkeley Pit and never took flight again. A total of 342 carcasses were recovered. Since the incident a bird watch program was implemented.

United States - Montana