Mount Bold Reservoir Reserve is located within the southern Mount Lofty Ranges and contains the largest reservoir in South Australia. The reserve is 5544 ha in size and is managed by SA Water. The focus of management is water quality and catchment management with access to the reserve restricted to ensure optimal water quality and environmental protection. Over half of the reserve contains remnant vegetation in moderate to excellent condition and as such is considered to be an important area of remnant vegetation within the southern Mount Lofty Ranges. The Nature Conservation Society of South Australia received funding from SA Water and the Adelaide and Mount Lofty Ranges Natural Resources Management Board to conduct a biological survey at Mount Bold Reservoir Reserve. Sixteen survey sites were established using Biological Survey of South Australia methodology in a variety of vegetation and habitat types. All 16 sites were surveyed for vegetation and bird species with most sites surveyed for mammals, reptiles and invertebrates.