This article originally appeared on the Pembina Institute website. This is part 2 of a series on the last 50 years of the oilsands industry. Read part 1 here.

The sheer size and scope of Alberta’s some 20 oilsands tailings ponds is unprecedented for any industry in the world.

According to the U.S. Department of the Interior, one of these ponds — the Mildred Lake Settling Basin — is the world’s largest dam by volume of construction material.

Since oilsands mining operations started in 1967, 1.3 trillion litres of fluid tailings has accumulated in these open ponds on the Northern Alberta landscape. This is enough toxic waste to fill 400,000 Olympic swimming pools.

Unlike tailings produced from conventional hard rock mining, the solids in oilsands tailings will take centuries to settle to the bottom of the ponds. As a result, it is impossible to dewater the waste for timely reclamation without significant intervention.

This problem was recognized as early as 1973 by the Government of Alberta, which identified oilsands tailings as untreatable with existing technologies.

The government recognized that the “continuous accumulation of liquid tailings” was not acceptable and that the ponds must be “restricted in their size, location and duration of use.”

Unfortunately, that is not what happened.

For the next five decades, industry pushed its tailings problem into the future with promises that forthcoming technologies would emerge to deal with them. As the years passed and tailings continued to grow, both industry and government assured Albertans that a silver-bullet technology was just one lab discovery away.

In 2010 Suncor’s CEO Rick George announced “massive change” on the tailings front, which would soon reduce Suncor’s ponds from eight to one. In 2013, Premier Alison Redford declared that tailings ponds would “disappear from Alberta’s landscape in the very near future.”

These promises were never met, however, and today the tailings problem is worse than ever.

According to new plans currently under review by the Alberta Energy Regulator, industry is proposing to let tailings continue to accumulate until 2037 when there will be over 1.5 trillion litres. That will equate to seven decades — from 1967 to 2037 — of industry seeking a technological solution and failing to meaningfully address this massive environmental problem.

Figure 1. Fluid tailing ponds volume growth since 1968

With tailings ponds continuing to grow on the landscape, the risk of failure poses an ever-increasing risk to communities, the environment, and taxpayers.

Moreover, should the oilsands mining industry not survive accelerating global transitions toward decarbonized energy systems, Albertans must be protected from being left behind to foot the bill for enormous clean-up costs.

The Problem of Alberta’s Growing #Oilsands #TailingsPonds is Worse Than Ever https://t.co/nwszGniwa0 @Pembina #ableg #cdnpoli

— DeSmog Canada (@DeSmogCanada) October 23, 2017

However, less than 8 per cent of these costs is held as security by the province, leaving Albertan taxpayers exposed to a significant financial risk for tens of billions of dollars if major companies are no longer around when it’s finally time to reclaim these sites.

Looking at these grim facts, it’s worth asking: when will we as Albertans say enough is enough? Companies have kicked the can down the road on cleaning up their tailings for five decades now, but industry’s own forecasts indicate that the worst is still yet to come.

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