Suncor Energy head office is pictured in Calgary, Alberta June 17, 2009. Credit: Reuters/Todd Korol

(Reuters) – Contaminated water may have spilled into the Athabasca River from a broken pipe at Suncor Energy Inc's oil sands project in northern Alberta, sparking new fears about pollution of the river from the massive oil sands developments along its banks.

The Athabasca is the main source of drinking water for aboriginal and other communities downstream and has been the subject of several controversial reports on its water quality.

The province of Alberta's environment department said it does not yet know whether the water that spilled from a holding pond contained toxic materials. Samples from the pond are being sent for analysis and it will take at least a day before results are returned. Environment department staff have been at the project site north of Fort McMurray, Alberta, since early on Monday.

Wayne Wood, a spokesman for provincial Environment Minister Diana McQueen, said the volume of water sent into the river has not yet been determined.

"We're on the ground monitoring the situation," Wood said. "The pipe got turned off relatively fast."

Suncor, Canada's No. 1 oil producer, and other oil sands companies store contaminated water, a byproduct of stripping tar-like bitumen from the sands, in holding ponds. Those ponds became the focus of environmental protests in 2008, when 1,600 ducks died after landing on a tailings pond operated by Syncrude Canada Ltd.

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