Alberta's Oil Sands: Dirty Birds and Broken Promises

It was not a lake, but a tailings pond - a store for toxic waste from the oil sands extraction process, made up of water, clay, sand, residual bitumen and heavy metals.

Most of the ducks died, killed by the slick of oil on the water's surface.

"It was horrifying," says Ruth Kleinbub, a field naturalist in nearby Fort McMurray, the city at the heart of the industry in the province of Alberta.

It is an argument that environmentalists say the government has lost.

"When we are looking at the tar sands, we are looking at a project that is the largest capital investment project on the face of the planet, the largest industrial project on the planet, and the ecological implications are just as great," says Mike Hudema, an Edmonton-based climate and energy campaigner with Greenpeace Canada.

Oil sands production, which requires large amounts of energy and water to extract the bitumen from the sand, is said to produce on average at least three times the greenhouse gas emissions of conventional oil extraction.