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British and American media are buzzing about the world's largest beaver dam, which is in northern Alberta and was first found using Google Earth in 2007.

The dam on the southern edge of Wood Buffalo National Park is about 850 metres long. It's common for beaver dams in Canada to reach 500 metres in length.

Park officials said the dam is in an inaccessible part of the park just south of Lac Clair, about 190 kilometres northeast of Fort McMurray.

Biologists estimate the dam would have taken at least 20 years to build. It is visible in NASA satellite imagery from 1990.

The dam first jumped into the global spotlight a few years back.

"[Beavers] are one of the few species that really leave a footprint on the Earth that is visible from satellite," ecologist Jean Thie told CBC News in an interview in 2008.

Thie said he discovered the dam while scanning satellite images for signs of climate change.

The previously reported largest beaver dam was a 652-metre structure in Three Forks, Mont., Thie said.