In the oil-rich province, companies are required to return mine sites to their previous condition after projects are no longer in service.

“The AER estimates over $45 billion in remediation and reclamation liabilities in the oilsands. This number may be a dramatic underestimate, with figures in leaked, official presentations suggesting as much as $130 billion in liabilities covered by less than $2 billion in security deposits,” University of Calgary School of Public Policy researchers Martin Olszynski, Andrew Leach, Drew Yewchuk wrote in a recent paper.