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We continue to investigate and respond to two separate Imperial Oil incidents that occurred at Imperial’s Kearl Oil Sands Project (Kearl) site in the Athabasca Oil Sands Region of Alberta, approximately 45 kilometres northeast of Fort McKay.

The first incident, reported on May 19, 2022, was initially reported as discoloured water found on the Kearl lease but was later identified to be industrial wastewater seeping from the external tailings area in four locations, both inside and outside the boundaries of the Kearl site. The second incident, reported on February 4, 2023, involved an uncontrolled release of industrial wastewater from an overflow storage pond. Imperial initially estimated that 2 m3 of wastewater was released, but it was later confirmed to be approximately 5300 m3.

The AER has launched a formal investigation into these two incidents. As such, we are unable to provide additional information related to the incidents beyond what has been provided in the environmental protection order (EPO).

What Happened

The following is a summary of events. A more detailed timeline can be found in the EPO issued to Imperial on February 6, 2023.

Incident 1: Seepage event (Release 1)

On May 19, 2022, Imperial reported to the AER that discoloured surface water was found at locations on the north and northeast sides of the Kearl lease boundary near the external tailings area (ETA).

Following two site inspections by the AER on May 20 and June 6, 2022, the AER requested that Imperial submit action plans to assess and monitor the impact to the environment (including groundwater, surface water, and soil), fish and wildlife, and to assess the structural integrity of the ETA dike.

Over the summer, with regulatory oversight from the AER, Imperial conducted a geochemistry study and drilled additional groundwater monitoring wells to determine the source and pathway of the discoloured water (i.e., how the substance travels through the environment). Imperial also implemented an AER-approved interim water quality sampling and monitoring plan, which included reporting to the AER every two weeks.

In Imperial’s August 16, 2022, submission to the AER, it was found that chemistry of the substance was consistent with that of industrial wastewater and that the substance exceeded Alberta Environment and Protected Areas (AEPA) and Canadian Council of Ministers of the Environment (CCME) guidelines for constituents, including dissolved iron, total arsenic, F2 hydrocarbons, sulphate, and total sulphide.

The AER issued two notices of noncompliance on September 2, 2022, under sections 4.2.1 and 4.2.3 of Imperial’s Environmental Protection and Enhancement Act (EPEA) approval. The noncompliant activities relate to releasing a substance from the site to the surrounding watershed and failing to manage and contain the industrial wastewater as per their EPEA approval.

A notice of noncompliance notifies a regulated party in writing that it is noncompliant with a specific regulatory requirement, requests that it address the noncompliance, and it may include a recommended course of action that is expected to achieve compliance.

Imperial continued water quality monitoring and investigation of the pathway of the release to inform source control options of the substance with regulatory oversight from the AER.

On November 29, 2022, Imperial confirmed that the substance released was industrial wastewater and that it was seeping from its ETA through a common fill layer placed during construction, mixing with shallow groundwater, and coming to surface at locations on site and off-site.

In December 2022, Imperial began installation of additional seepage interception wells and delineation groundwater wells along the perimeter of the site.

On December 22, 2022, and January 27, 2023, Imperial submitted action plans for source control, delineation, and remediation of the release. Also in its December 22, 2022, submission, Imperial provided an action plan to the AER that included actions both onsite and off-site to prevent further release; however, the timelines for off-site actions would not have allowed for the work to be completed before spring runoff. At that time, the AER determined that additional work was required to ensure the source of the release would be controlled before spring runoff to prevent further environmental impacts.

Incident 2: Overflow event (Release 2)

On February 4, 2023, Imperial reported to the AER an additional release of industrial wastewater near the first release due to an overflow of an industrial wastewater storage pond. The initial estimate of the volume released was 2 m3.

On February 5, 2023, the AER conducted a site inspection and observed that the area affected included the site and areas outside the site, including muskeg and forested area. Imperial also informed the AER that the estimated volume released had increased to 5300 m3.

What We Have Done

The AER issued an EPO to Imperial on February 6, 2023, pursuant to section 113 EPEA. Under the EPO, Imperial is required to take action and submit and implement plans related to communications, control, containment and delineation, sampling and monitoring, wildlife mitigation and monitoring, and remediation. The AER reviews and approves these plans, and Imperial is required to implement them as approved.

Members of the AER senior leadership team have also reached out to stakeholders., including visiting the work underway on site at Imperial Kearl and meeting directly with Indigenous communities to answer questions and actively listen to concerns. The AER will continue to provide updates to potentially affected communities and is actively monitoring the situation at the Kearl site to ensure Imperial is taking the necessary actions to comply with the EPO.

The AER continues to oversee Imperial’s compliance with the EPO to ensure the regulator’s top priorities of public safety and the protection of the environment.

Third-Party Sampling Results

The following are sampling results from the monitoring at the Kearl site conducted by an independent third-party on behalf of the AER. Data will continue to be updated as it is received.

  • Third-Party Sampling Data - September (as of November 17) [PDF] [XLSX]
  • Surface Water, Ground Water and Soil Data as of:
  • May 8, 2024 [PDF]
  • November 17, 2023 [PDF]
  • October 20, 2023 [PDF]
  • September 15, 2023 [PDF]
  • August 11, 2023 [PDF]
  • July 14, 2023 [PDF]
  • June 28, 2023 [PDF]
  • June 16, 2023 [PDF]
  • April - May, 2023 [ZIP]


Separate from the EPO, the AER conducted sampling of two areas of standing water, one north and east of Drainage Pond 4 and the other north of Polishing Pond 4.The results [PDF] show no discernible presence of industrial wastewater.

Additional information and data is available on the Fort Chipewyan Working Group and Oil Sands Monitoring Program - Scientific papers and data pages on the Government of Alberta website. 

Community Updates


Related Information

  • Read the statements we issued about the incidents.
  • Learn more about the AER's role in incident response and how we conduct investigations.
  • Visit our Compliance Dashboard for an overview of incidents that have occurred, active and closed investigations and noncompliance and enforcement activities.  
  • For more information about how Imperial is responding to the incidents, visit the updates page on their website.