Discharge of red mud can be hazardous environmentally because of its alkalinity and species components.
Until 1972, Italian company Montedison was discharging red mud off the coast of Corsica. The case is important in international law governing the Mediterranean sea.
In October 2010, approximately one million cubic meters of red mud slurry from an alumina plant near Kolontár in Hungary was accidentally released into the surrounding countryside in the Ajka alumina plant accident, killing ten people and contaminating a large area. All life in the Marcal river was said to have been "extinguished" by the red mud, and within days the mud had reached the Danube. The long-term environmental effects of the spill have been minor after a  remediation effort by the Hungarian government.