Activists from Greenpeace shut off a tailings pond sludge pipe at an Alberta Tar Sands operation on Thursday, July 24, locking down to the valve pipe and deploying several banners calling for an end to tar sands mining. Eleven people were arrested.

The protest took place at the Aurora North Tar Sands facility north of Fort McMurray, operated by Syncrude Canada Ltd. and owned by Canadian Oil Sands Limited, ConocoPhillips Oilsands Partnership II, Imperial Oil Resources, Mocal Energy Limited, Murphy Oil Company Ltd., Nexen Oil Sands Partnership, and Petro-Canada Oil and Gas.

Petroleum mining in Alberta’s tar sands is the province’s single biggest user of fresh water, consuming more than 2.5 times the water used by the entire city of Calgary. This water is permanently contaminated by the process and is stored in massive toxic tailing ponds that can be seen from space. The Greenpeace protest took place at the same site where a flock of 500 ducks drowned in one of these ponds in April.

The tar sands have attracted widespread opposition for their contribution to global warming, contamination of the environment, and effects on local communities. The downstream First Nation community of Fort Chipewyan, for example, has suffered from sharply elevated rates of rare cancers since the Syncrude project began.