Unearthing trends in environmental impact assessments for mines and quarries across Canada

In Canada, at least 200 active mines and 6500 quarries produce 60 commodities. Many proposed mines and quarries undergo impact assessment (IA) to predict potential impacts and inform final decision-making, alongside conditions for mitigating risk. We (1) present the first complete list of IA laws that apply to mining in Canada; (2) provide an open-source database of mine and quarry projects subject to IA; (3) quantify mining and IA trends; and (4) assess availability of information by jurisdiction. Our database includes 266 assessments of 227 projects under 13 jurisdictions proposed from 1974 to 2023. Over time, target commodities shifted from coal, oil sands, and peat, to metals (e.g., gold, copper, nickel) and production sizes increased. For many projects assessed across multiple jurisdictions, we could not explain differences in reported key metrics (production size, lifespan, footprint). Our database's comprehensiveness is limited by a lack of publicly available data. We recommend regulators adopt the findable, accessible, interoperable, and reusable principles for information sharing by standardizing key metrics, publishing project documentation, and improving registry functionality. We encourage enhanced inter-jurisdictional IA cooperation to ensure the public and decision-makers have access to fulsome information about new projects during a modern mineral rush in Canada.