Oil sands mining effluent

Environment and Climate Change Canada (ECCC) is exploring options to manage the accumulation of oil sands process-affected water in existing tailings ponds located in the Athabasca Oil Sands Region (AOSR).


Oil sands deposits consist of bitumen bound tightly with sand. Where these deposits exist close to the surface, oil sands mining operators extract the deposits using open-pit mining methods. The extraction process uses hot water to separate the bitumen from the sand. This process produces tailings as a by-product.

Oil sands tailings are a mixture of sand, silt, clay, residual bitumen, and contaminated process-affected water. Process-affected water contains many compounds that may be harmful to the environment if released without treatment. These include:

Oil sands mining operators store tailings on-site in large tailings ponds. In tailings ponds, the fine tailings particles slowly separate out, and settle at the bottom of the pond. Then, the process-affected water in these ponds is re-used in the extraction process. Despite heavy water re-use by operators, additional fresh water is still required on an ongoing basis. In the decades since oil sands mining began, this added fresh water use, together with captured precipitation in the tailings ponds has led to the accumulation of substantial process-affected water volumes.

Crown-Indigenous Working Group

Canada is committed to Indigenous Reconciliation and the United Nations Declaration on the Rights of Indigenous Peoples (UNDRIP). For the people and wildlife who live in the oil sands region, the Athabasca River’s importance is paramount. Many Indigenous communities have stated that they rely on the continued health of the Athabasca River watershed for their livelihoods.

In recognition of the importance of the Athabasca River to Indigenous communities, ECCC and nine Indigenous communities established a Crown-Indigenous Working Group (CIWG) for the potential Oil Sands Mining Effluent Regulations in 2021. This group is leading the work to explore options to manage the accumulation of oil sands process-affected water in existing tailings ponds located in the AOSR. The group will co-develop discussion papers for release to the public and other materials and recommendations for a path forward.

One of the options under consideration is the potential development of regulations under the Fisheries Act. The Fisheries Act prohibits the deposit of deleterious substances in water bodies containing fish or in any place where the deleterious substances may enter any such water, unless authorized by a federal regulation. No such regulation is in place for oil sands mines, meaning there is currently no federal authorization to release oil sands process-affected water as effluent.

If developed, regulations would allow releases of treated effluent into the Athabasca River and its tributaries under certain conditions. Regulations would be developed with strict protective standards reflecting the best available scientific information and Indigenous knowledge. While regulatory development is in the early stages, CIWG is exploring effluent quality standards that could include:


Engagement document

This document is to:

Interested parties may submit comments in writing by e-mail or by mail using the contact information below by October 6, 2023 (extended from September 15, 2023).

Note: Please read our privacy statement for this engagement period. Complementary to the privacy statement, note that:

Engagement sessions

We will be holding engagement sessions on the document with organizations and community representatives. If you are interested in participating, please contact us by July 15, 2023 with the following information:

Participant funding

Funding may be available for Indigenous communities and environmental non-governmental organizations (ENGOs) to participate in the engagement sessions.

Representatives should submit an expression of interest to receive funding for participation in the engagement sessions, by e-mail or mail by July 15, 2023.

Relevant Links




Contact us

Environment and Climate Change Canada
Regulatory Development and Analysis Section
Mining and Processing Division
351 boul. St-Joseph, 11th floor
Gatineau QC  K1A 0H3
Email: sb-os@ec.gc.ca

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