Open cut mining pits and pit lakes: a collation to assist prioritization of pit lake types across Australia

Australia has a significant legacy of mining activity, encompassing over 100,000 spatially referenced locations that comprise operational, orphaned, or closed mine sites and broader mining occurrences. As shallower ore bodies are depleted, deeper excavations will become necessary, creating additional and more complex pits making the closure or repurposing of these pits, and the assessment of associated risks and beneficial uses, a critical undertaking. This study compiled a comprehensive database of Australian pits/pit lakes to facilitate targeted investigations and prioritization of future actions. From a national baseline dataset of approximately 107,854 mine sites and mining occurrences, we visually identified 2,446 mining voids (comprising both existing dry pits and pit lakes) through satellite imagery. Pits/pit lakes were categorized by jurisdiction, commodity type and climate zone. The ‘pits per mine site’ ratio varies significantly across Australian state and territory jurisdictions, from a high of 0.178 in the Northern Territory to a low of 0.004 in New South Wales, highlighting the diverse nature of mining operations and landscapes across the continent. We identified ten representative pit lake clusters based on morphology and potential water quality deterioration. Key prioritization factors are discussed, including proximity to population centres or sensitive ecosystems, cultural significance to Australia’s First Nations peoples, and potential for beneficial reuse. This expandable and publicly available database provides a valuable resource for informed decision-making regarding management of existing and potential pit lakes in Australia.