Imperial Oil Ltd. spilled crude from its Mihihkan plant at the Cold Lake oil-sands site, contaminating a flock of geese in the latest environmental mishap at the company’s facilities.

An operational issue caused 900 liters (5.7 barrels) of crude to be released into a process-water lagoon on July 24, the Alberta Energy Regulator said on its website. Later, a flock of 12 geese became stained after landing in the lagoon. Wildlife deterrents such as cannons have been deployed around the site, containment booms have been added to prevent the oil from spreading and the site is under 24 hour surveillance. The birds were taken to a facility for cleaning and rehabilitation.