Earlier this fall, Canadian Natural Resources Ltd. (TSX:CNQ) was told it must remove most of the water from one of its bitumen leak sites — a small lake — before it freezes.
On Monday, the company was told it must also determine the impact to subsurface groundwater and work to find the root cause of all four bitumen releases.
The province says that will require a drilling program, adding that doing so in the winter months minimizes the environmental impact of the drilling activities.
In July, Canadian Natural Resources said a mechanical failure at an old well was behind bitumen seepage at its project on the Cold Lake Air Weapons Range.
Four sites were identified and about 1.5 million litres of bitumen has since been recovered.
More than 100 animals have also died in the area.
The Calgary-based company has said the four locations have been secured and cleanup is ongoing.
The company had earlier been ordered to limit the amount of steam it pumps into the reservoir while the Alberta Energy Regulator investigates.
Mike Hudema with Greenpeace Canada has called the leak an ongoing disaster.
"(It) shows how hard it is to clean up tar sands incidents and the extreme nature of these spills," he said in September.
"As the spill numbers and questions rack up, the Alberta government should, at a minimum, put a hold on approving new underground tar sands operations until we understand how these leaks are happening and if other sites could run into similar problems.''
Also on HuffPost