Water impacts and effluent quality regulations of Canadian mining

Energy transition relies on the scaling up of mineral production and may lead to increased pressure on water resources due to the intensity of water use in mining. The status of Canada as a major mineral producer and a country with effective environmental regulations prompted our study of the water impacts of Canadian mining. In 2002, the Canadian government introduced effluent quality regulations that targeted metal mining companies. By analyzing regional and sectoral data, we find that such regulations were important for mitigating both the water quality and water quantity impacts of metal mining. Despite increasing output, metal mining reduced its contribution to total mining withdrawals and discharge from 85% in the pre-regulation period to 62–65% in the post-regulation period. In the absence of such regulations, non-metallic mineral mining and, in particular, coal mining, increased their pressure on water resources. Finally, we find that since 2002, over 90% of regulated operations have met effluent quality standards. However, we document increased flows of discharge to mine tailings, a development which requires further analysis.