Gold mining in Victoria began during the 1850s gold rush and continues to this day. Alluvial gold was initially found using basic panning techniques, however techniques quickly progressed to mining buried gold deposits, motivating the need for new extraction methods. As a result, two environmental pollutants emerged: mercury and arsenic.

EPA Victoria is leading a project to identify ‘hotspots’ of freshwater stream contamination occurring on multiple scales as a result of Victoria’s past gold mining activities. Our adopted approach has been to spatially analyse gold mining data in conjunction with data on stream health, soil types, geology and hydrology to determine areas of concern. In addition to spatial analysis, intelligence from Catchment Management Authorities has influenced the identification of ‘hotspots’. Our analysis shows some of the worst affected areas fall within the tribal boundaries of the Djadja wurrung and Wada wurrung in the west of the state, and those of the Daung wurrung and Waveroo in the east. This information will be used in catchment management and potential remediation works.

Our ‘hotspot’ analysis has now guided the selection of a series of field sampling sites for mercury and arsenic. Environmental samples (water, sediment, soil) from control and impact sites around former gold mine locations provide a current context for conditions. Bioaccumulation is also examined through the analysis of tissue from the common yabby Cherax destructor. Characteristics of this species make it a suitable bioindicator and additionally it provides information for health authorities, given C. destructor is commonly consumed by recreational fishers.