Animals affected by the bitumen leak near Cold Lake are being cleaned at a wildlife rehabilitation facility in Edmonton.

Six animals have been brought to the facility where they were scrubbed with dish soap and thoroughly rinsed with water. One muskrat has already been released back into the wild. 

About 60 other birds and animals have died.

Wildlife rehabilitation specialist Colleen Doucette says oil contamination hurts animals' natural waterproofing.

"It allows the water to go through to the skin ... and they're no longer able to maintain their core body temperature," she said.

"They become hypothermic and can die from that. Very quickly actually."

The bitumen has been seeping for weeks at an old well at a Canadian Natural Resources Ltd. site on the Cold Lake Air Weapons Range. 

The company said on Wednesday that the leak has been contained and was caused by a "mechanical failure."

With files from The Canadian Press