On Oct. 4, 2010, a million cubic meters (35 million cubic feet) of red sludge spilled from a reservoir at an alumina plant in Ajka in western Hungary. Four people were killed and about 100 injured. The sludge entered the Marcal River and has reached

On Oct. 4, 2010, a million cubic meters (35 million cubic feet) of red sludge spilled from a reservoir at an alumina plant in Ajka in western Hungary. Four people were killed and about 100 injured. The sludge entered the Marcal River and has reached the Danube. Aquatic life in the Marcal was severely harmed; the mud also caused significant damage in nearby villages and towns, as well as adjacent farmland. On Oct. 11. Satellite image. (Photo by: Universal History Archive/Universal Images Group via Getty Images)