Dilution is not the Solution to Pollution: Toxic Tailings Ponds and Issues with the Proposed ‘Treat and Release’ Program

April 6, 2026

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Wildlands Advocate article by Pamela Narváez-Torres, AWA Conservation Specialist

Read the PDF version here.

 

Concerns surrounding the oil sands, from environmental damage to human health risks, are nothing new in Alberta. What is new right now is how urgently the provincial government is trying to address one of the industry’s longest-standing problems: tailings ponds. These are massive human-made lakes of sand and fluids that hold toxic waste from the oil extraction process. One of the main reasons for this urgency is likely related to the provincial government’s intentions to double oil and gas production. That raises an obvious question: where will all the additional industrial waste go?

Alberta is already facing multiple challenges related to the oil and gas industry: companies are walking away from inactive wells rather than reclaiming them, repeated spills are happening in the oil sands, wildlife deaths are being linked to tailings ponds, and so on. In the case of the oil sands, water sits at the centre of nearly every issue. Large quantities of water are withdrawn from rivers and aquifers, contaminated through extraction, and then stored — often indefinitely — in massive tailings ponds.

The Alberta oil sands: A brief overview

The Alberta oil sands underlie approximately 140,000 square kilometres, covering roughly 20 percent of northern Alberta. The oil sands are a mixture of sand, clay, and bitumen (a heavy, highly viscous form of oil). About 20 percent of this resource is close enough to the surface to be extracted through open pit or surface mining, while the remaining 80 percent is extracted using in situ (“in place”) methods deep underground.

Although the extraction techniques differ, both require large amounts of water and energy.

In surface mining, oil sands are dug from open pits and transported to processing facilities. There, hot water is added to separate bitumen from sand and clay. Then, the bitumen is skimmed off and sent for upgrading. What remains is a slurry of water, sand, fine clay particles, and toxic waste. This waste is pumped into tailings ponds, where solids are supposed to settle so that the water can be reused. In reality, much of this material remains suspended, creating a toxic mixture that can persist for decades.

On the other hand, in situ operations recover bitumen without excavation, typically by injecting steam underground to heat the bitumen so it can flow. While these projects do not create tailings ponds, they still rely on large volumes of water, most of which must be recycled and supplemented with fresh water. In situ operations also use much more methane to heat the massive amount of injected hot water and steam required. In situ mining uses about three times the methane per barrel of bitumen produced when compared to open pit mining.

According to data from the Alberta Energy Regulator (AER), oil sands operators reported using approximately 257 billion litres of freshwater in 2024 to produce 698 million barrels of oil equivalent (BOE). This amounts to about 368 litres of freshwater used for every BOE produced. Even with current recycling rates (almost 78 percent), freshwater withdrawals remain substantial.

It is important to note that these figures are self-reported by companies and are not independently audited, so while these are the best publicly available numbers, they may not capture the full picture. The oil sands industry has previously faced criticism for underreporting air emissions; thus, the same concerns are shared over water use reporting.

Tailings ponds: A toxic legacy

Oil sands operations began in Alberta in the late 1960s. After more than five decades, tailings ponds have become one of the most visible and persistent symbols of environmental harm from the industry. Despite repeated assurances that tailings ponds would be temporary, their footprint has grown by nearly 300 percent over the past two decades, and not a single tailings pond has been fully reclaimed.

Regardless of their name, tailings “ponds” are massive industrial waste reservoirs, stretching for kilometres and replacing boreal forest, wetlands, and waterways. By 2020, they already held more than a trillion litres of contaminated water and covered more than 300 square kilometres, which is equivalent to over 2.6 times the size of Vancouver.

These tailings ponds contain hundreds of chemicals. Some occur naturally in bitumen, while others are added to the water mixture during processing. Among the most concerning chemicals are naphthenic acids, which are acutely toxic and linked to harmful effects in fish, amphibians, birds, and mammals. Other chemicals found in tailings, such as polycyclic aromatic hydrocarbons, are known or suspected carcinogens.

Tailings ponds are known to leak into surrounding groundwater, emit greenhouse gases, and pose persistent risks to wildlife.

In 2008, 1,600 ducks died after landing on a Syncrude tailings pond. Two years later, the company was fined $3 million, the largest environmental penalty in Canadian history at the time.

In 2022, a tailings pond connected to Imperial Oil’s Kearl mine leaked, allowing 5.3 million litres of toxic wastewater to overflow into the environment, along with an unknown volume of tailings that leaked off-site. The leak was not disclosed to local Indigenous communities or the federal government for nine months. In July of 2024, the AER issued a fine of just $50,000. Ecojustice, on behalf of AWA and others, requested that the AER reconsider the penalty and apply the law to the full extent; however, they refused to revisit the decision.

Why “treat and release” is being proposed

For decades, governments allowed oil sands development to proceed without requiring proven methods to process tailings safely. Storage became the default solution. Now, storage capacity is becoming a big challenge.

In September 2025, the Oil Sands Mine Water Steering Committee provided recommendations to the provincial government. One of the nine recommendations included developing standards that would allow treated tailings water to be released into natural water bodies, such as the Athabasca River.

If you’re not familiar with the scale and toxicity of tailings, “treat and release” may initially sound reasonable. The idea seems simple: treat contaminated water until it meets regulatory standards, then discharge it into rivers. But there’s a catch: those regulatory standards do not yet exist, and we have no idea what they will look like or how strict they will be.

At the federal level, Environment and Climate Change Canada (ECCC) released a 2025 discussion paper exploring policy options for managing tailings water. Developed with input from Indigenous communities in Alberta, the paper considered whether federal regulations could allow the release of treated tailings water into the environment. ECCC acknowledged that the document may not have fully or accurately reflected the positions of all Indigenous groups involved.

AWA and other groups have opposed any regulatory framework that would allow treated tailings to be released into the Athabasca River watershed, arguing that discharge should remain prohibited until a truly safe solution exists.

What “treat and release” could really mean

Treat and release does not mean removing all contaminants — it means reducing some pollutants to levels deemed “acceptable” under future regulations, then relying on the receiving river to dilute whatever remains.

In other words, dilution becomes part of the treatment strategy.

Some contaminants are especially difficult to remove. For example, salts are a major challenge for the oil sands industry, and currently discussed treatment approaches would not remove these salts. Considering the massive volumes associated with treat and release, even small remaining concentrations could translate into large total salt loads entering the Athabasca River. Over time, these salts could then accumulate downstream, including in sensitive areas, such as the Peace-Athabasca Delta.

This approach raises serious concerns, especially in a province already experiencing drought conditions and low river flows. Less water means less dilution capabilities and higher ecological and health risks.

Treat and release also assumes we fully understand what is in tailings water, how different contaminants interact, and how aquatic ecosystems will respond over time. We do not. There is no comprehensive inventory of all toxic substances in tailings. We lack watershed-wide contamination assessments and long-term population health studies for downstream communities. Even the effectiveness of available treatment technologies at this scale remains uncertain.

Why this matters

The Government of Alberta and the AER have repeatedly been criticized for failing to ensure environmentally responsible oil sands development. In 2020, the Commission for Environmental Cooperation (CEC) reported that despite containment systems, millions of litres of tailings water were seeping into the environment daily. In 2025, research by senior ecologist Dr. Kevin P. Timoney highlighted major gaps in how the AER monitors and reports tailings spills, finding that 97 percent of reported spills between 2014 and 2023 were not inspected, contradicting the AER’s claim of routine spill inspections.

At the federal level, ECCC and Health Canada are still assessing whether key tailings contaminants, such as naphthenic acids, should be classified as toxic under the Canadian Environmental Protection Act. Making decisions about discharge standards before that assessment is complete would be extremely irresponsible.

Under the Fisheries Act, releasing deleterious substances into fish-bearing waters is currently prohibited. Treat and release would require either redefining what counts as deleterious or weakening existing protections.

Shifting risk, not solving the problem

From an industry perspective, treat and release is attractive. It reduces liabilities associated with storing vast volumes of toxic water, lowers the risk of catastrophic pond failures, and is far cheaper than treating tailings to a standard suitable for recycling.

But this convenience comes at a cost, one carried by the environment and by present and future generations living downstream. Once contaminants are released into a river system, they cannot be taken back. Some may settle into sediments, enter food webs, bioaccumulate, or re-emerge years later. Treatment may lower concentrations, but it does not eliminate risk — it just redistributes it.

This is not a solution. It is risk transfer.

Treat and release is being framed as a practical solution to an urgent problem. In reality, it risks creating an even lower standard of environmental protection while enabling continued and expanded production.

Industry should not be more important than environmental integrity, human health, or Indigenous rights. Any tailings strategy must result in a net reduction of toxic water on the landscape, not justify producing more of it. Dilution should not be the solution to pollution.

Until tailings water can be treated to a standard that is demonstrably safe across seasons, flow conditions, and generations, releasing it into already stressed river systems should not be on the table.

What is being proposed is not a fix for decades of accumulated toxic waste — it is a shortcut. And shortcuts, in complex ecosystems, have a long history of backfiring.