The regulator says Canadian Natural Resources Limited (TSX:CNQ), Suncor Energy Inc. (TSX:SU) and Syncrude followed the rules that require them to use devices to scare waterfowl away from the ponds.
Ryan Bartlett, a spokesman for the regulator, says the birds still managed to land on the oily water on Nov. 4 due to bad weather in the area near Fort McMurray, including fog and heavy, wet snow.
The devices include noise makers and structures similar to scarecrows.
Syncrude, which operates one of the biggest oilsands sites, was fined $3 million for the deaths of more than 1,600 ducks when they landed on its tailings pond in 2008.
In October 2010, more than 550 birds had to be destroyed when an early winter storm forced the birds to land on the toxic waste ponds belonging to Syncrude and Suncor.
"The Alberta Energy Regulator has reviewed the recent waterfowl impacts in the Athabasca oilsands area and has determined that the oilsands mining operations involved were in full compliance with waterfowl protection equipment requirements at the time," Bartlett said Thursday.
"Unfortunately, the intense weather conditions on Nov. 4 forced the waterfowl to land on the ponds in spite of the deterrents."
Bartlett said the investigation is closed.
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