Jennifer Grant/Pembina Institute
A mine in the Alberta oil sands. The tailing ponds from these mines are leaking water into the Athabasca River, a new Canadian study says.

Large Dams of Mining Waste Leaking Into Athabasca River: Study

Andrew Nikiforuk, The Tyee

Polluted water from large man-made lakes of oilsands mining waste is fouling the Athabasca River, says a new federal study.

The new report by the Joint Oil Sands Monitoring Program shows that waste from dams covering 176 square kilometers of land (68 square miles, an area 1.5 times bigger than Vancouver) is leaking into groundwater.

The study, which found a better way to track and separate oil sands pollution from natural bitumen sources in the region, describes one dam seeping mining wastewater at a rate of 75 liters (about 20 gallons) a second, or 6.5 million liters (1.7 million gallons) of waste a day into groundwater feeding the Athabasca River.

It also describes a plume of tailings contaminants in groundwater that extends out at least 500 meters (1,640 feet) from another tailings pond.

The dams contain a variety of chemical hazards including bitumen, naphthenic acids, cyanide, phenols and metals such as arsenic and cadmium.

"In short, [the study] highlights past studies identifying tailings ponds as significant sources of groundwater contamination, and brings to light that groundwater contaminated by leaking tailings ponds is almost certainly flowing into the Athabasca River," says William Donahue, an Edmonton-based specialist in freshwater science and policy.

The chemical fingerprints of pollution from the tailing ponds are complex, but can now be separated out from natural sources.


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