Environment Canada opens Fisheries Act investigation into Kearl tailings releases

Tailings samples are tested during a tour of Imperial's oil sands research centre in Calgary on Tuesday, Aug. 28, 2018. (Jeff McIntosh)

Environment Canada is opening an investigation into whether Imperial Oil broke federal laws with two releases of tailings from its Kearl oilsands mine in northern Alberta.

The federal agency's enforcement branch says it is looking into whether the releases broke the Fisheries Act, which forbids putting hazardous materials into waters inhabited by fish.

In May 2022, Imperial workers discovered what they at first called discoloured water seeping from one of the mine's tailings ponds.

The substance was later found to be groundwater mixed with mine tailings.

Another release in February sent 5.3 million litres of contaminated surface water overflowing from a containment pond.

Environment Canada has confirmed the presence of hydrocarbons and naphthenic acids in a small fish-bearing lake located almost entirely within Imperial's lease

Federal inspectors have already said they believe the tailings-contaminated groundwater and surface water to be hazardous to wildlife.

This report by The Canadian Press was first published May 4, 2023.