The Gold Rush of California left a long-lasting mark of pollution in the River systems of California. Northern California Gold mine runoff largely contributes to the elevated levels of mercury found in the river systems, such as, the Sacramento River. The mining of mercury along coastal ranges and its use in processing gold in the Sierra Nevada area is the reason for increased levels of this heavy metal. As mercury travels down the California River system it gets deposited along the river and buried under or with other sediment. Due to the burying of this heavy metal, increases in mercury in the actual river water can be seen during peak storm flow when the water is capable of holding more sediment due to its increased capacity and speed. The mercury gets unburied and reintroduced into the flow of the river water. One of the problems that arise from having mercury in the California river system is bio accumulation. As fish are exposed to mercury in the river system it begins to accumulate in their tissues. When another organism eats a contaminated fish, they ingest the mercury that was in the fish, which then accumulates in their tissues. This causes a risk to human health as fisherman or hunters catch these fish, or predators of these fish, th