While the Government of Alberta promotes increased oil sands production, tailings ponds now cover 300 square kilometres of northern Alberta boreal forest, an area three times the size of Red Deer.
And they continue to grow, according to a joint report from Environmental Defense and the Canadian Parks and Wilderness Society released in May.
The report, titled 50 Years of Sprawling Tailings, points out that “despite the small scale implied by their name, tailings ‘ponds’ stretch as far as the eye can see – impacting healthy boreal systems, sprawling through Indigenous territories, leaking contaminants into groundwater and emitting greenhouse gasses.”
A toxic stew
Tailings are the waste byproduct of oil sands extraction, a process that uses high volumes of water and chemicals to separate bitumen from clay, sand and silt.
They contain toxins like arsenic, benzene, mercury, and polyaromatic hydrocarbons that can seep into the ground and waterways and drift in the wind.
The tailings are stored in manmade reservoirs that industry and government calls ponds. Solids settle to the bottom over time, allowing the water to be recycled and reused for industrial purposes.
But it can take up to an estimated 150 years for the solids to fully settle out.
These ponds, situated close to the Athabasca River, have grown steadily over the last 50 years. There are now more than 30 tailing ponds that collectively have serious downstream impacts on wildlife, fish, human health, and the Athabasca Chipewyan First Nation’s traditional rights and land access.
Regulation problem
The tailings ponds report blames weak provincial government regulation, enforcement and monitoring for this growing mess in Alberta’s oil sands.
Between 1975 and 2010 there were no regulations for tailings management and reclamation. During that time, fluid tailings grew from 1.5 to more than 73 square kilometres.
In 2009, the province introduced new regulations requiring companies to reduce fluid tailings within five years.
The regulations had no impact. When the report authors analyzed the numbers, they found that fluid tailing grew by 40 percent between 2010 and 2015.
Make polluters pay
In April 2025, the Athabasca Chipewyan First Nation (AFCN) filed a judicial review of the provincial government’s decision to renew the Mine Financial Security Program (MFSP.) The program collects money from industry to pay for cleanup at the end of a mine’s life.
The nation is arguing that the MFSP doesn’t protect Albertans from bearing the costs of oil sands clean-up nor does it protect treaty First Nations like the Athabasca Chipewayan from long term pollution.
“Without a properly funded program, industry will be able to walk away from their leases — leaving the mess behind for First Nations communities to live with,” said acting AFCN chief Hazel Mercredi in a media statement. “This is something that all Albertans should care about because it is an expense that will fall to taxpayers after industry has finished extracting billions of dollars in revenue — leaving you with the bill.”
Ballooning bill
As of 2016, the Alberta Energy Regulator (AER) had reclaimed just one square kilometre of tailing ponds. That’s 0.1 percent of the total contaminated area.
In 2018, the AER publicly estimated the cost of clean-up to be $28 billion. However, internal documents obtained by Environmental Defense through a freedom of information request in 2022 found that the price tag could be as high as $260 billion.
Alberta’s GDP in 2024 was $353 billion.
Suncor, Cenovus, Canadian Natural Resources Ltd., and Imperial Oil – the four oil sands giants – posted combined profits of almost $17 billion in the first three quarters of 2024.
