TOXIC METALS: acid mine drainage also dissolves toxic metals, such as copper, aluminium, cadmium, arsenic, lead and mercury, from the surrounding rock. These metals, particularly the iron, may coat the stream bottom with an orange-red coloured slime called yellowboy. Even in very small amounts, metals can be toxic to humans and wildlife. Carried in water, the metals can travel far, contaminating streams and groundwater for great distances. The impacts to aquatic life may range from immediate fish kills to sub- lethal, impacts affecting growth, behaviour or the ability reproduce.