This chapters focuses on the consequences mining on river contamination in Bolivia. An unintended consequence of mining has been widespread contamination of riverine environments by toxic trace metals and metalloids. (e.g., arsenic, antimony, cadmium, mercury, lead, and zinc). The type, magnitude, and extent of contamination differ significantly between the humid to hyperhumid tropical rainforests in the north and the semiarid, heavily impacted, rivers in the south.