Legacy Mercury Contamination from Historical Gold Mining

Mercury contamination from historic gold mining represents a potential risk to human health and the environment. There is a lack of public awareness of the history mercury use in gold mining and how it contributed to this situation, and also what the present concerns are. Specifically, the public is not aware of locations and levels of contamination. To address this situation, the USGS has created an interactive map explaining the presence of mercury and methylmercury in the northern Sierra Nevada in California. This how-to video introduces the map and explains how to navigate its features.