Expert Testimony on the Impact of Toxic Tailings on Groundwater

Ottawa | Traditional, unceded territory of the Algonquin Anishinaabeg People – Tomorrow, Environmental Defence expert Aliénor Rougeot, Climate and Energy Program Manager, will testify before the Parliamentary Environment Committee (ENVI) about the impacts of tar sands mining, including its toxic tailings waste on groundwater. This testimony comes on the first anniversary of Imperial Oil’s Kearl mine disaster in the tar sands, which spilled 5.3 million litres of toxic tailings into the surrounding environment.

Who: Aliénor Rougeot, Climate and Energy Program Manager, Environmental Defence.

When: Tuesday, February 6th, 2024.

Where: Ottawa, ON, and available remotely.

Rougeot will speak to the risks and impacts of the over 1.4 trillion litres of tailings (wastewater produced in the oil extraction process) on groundwater. The tailings contain a dangerous mixture of chemicals, including heavy metals and naphthenic acids. A recent scientific study has also revealed that tar sands companies have underreported their toxic emissions by up to 6300 per cent — a significant portion of which may be coming from toxic tailings. The full extent of the danger presented by oil sands process water on human health remains understudied.

Background Information:

  • Toxic tailings ponds now cover an area of over 300 sq km, equivalent to 2.6 times the size of the city of Vancouver.
  • In 2020, the Commission for Environmental Cooperation surveyed all publicly available peer-reviewed studies and concluded there is scientifically valid evidence of oil sands process water (tailings) seepage into the groundwater around tailings ponds.
  • In May 2022, Imperial Oil workers discovered tailings fluid leaking offsite from the company’s Kearl oil sands mine onto nearby land. Internal reports reveal that seepage from this tailings pond has been ongoing since 2020.
  • Imperial Oil reported the leak to the Alberta Energy Regulator (AER) and met with the provincial regulator, but the general public and nearby Indigenous communities were not informed about the extent and seriousness of the leak for over nine months.
  • In February 2023, 5.3 million litres of wastewater spilled from the same Imperial Oil tailings area. The toxic waste leaked into boreal wetlands and tributaries where water drains to drinking water sources. It was only through this second spill that Indigenous communities fully learned of the extent of the pervasive belowground leak, which is still ongoing to this day.

ABOUT ENVIRONMENTAL DEFENCE ( Environmental Defence is a leading Canadian environmental advocacy organization that works with government, industry, and individuals to defend clean water, a safe climate, and healthy communities.

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For more information or to request an interview, please contact:

Paula Gray, Environmental Defence,