Oil oozing out of the ground in northeast Alberta is killing wildlife and destroying vegetation, but government and industry scientists have no idea how to stop it or even what's causing it.

There have been four leaks at the Primrose Lake site on the Cold Lake Air Weapons Range near the Saskatchewan border since May 20, which have affected 13.7 hectares.

"We do know some animals have died – including waterfowl, beavers, tadpoles and frogs and shrews," said Nikki Booth, spokesperson for Alberta Environment and Sustainable Resources Development.

Access to the site has been limited to Canadian Natural Resources Ltd. scientists and government investigators, but Alberta Energy Regulator spokesman Bob Curran described the leaks as "basically cracks in the ground and bitumen emulsion is seeping out of these cracks."

He acknowledges "the challenges are basically figuring out what happened and then how to stop it."

Critics say the most troubling aspect of the leaks is they call into question the whole process of extracting oil by steam, which is how most oil in Alberta is produced.

Oil industry watchdog Chris Severson-Baker, with the Alberta-based Pembina Institute, points to an investigation of a similar spill in 2009 which failed to pinpoint the cause.

"The assumption is that companies and the regulators have a very good understanding of how much pressure the underground formations can tolerate, and yet this project is showing that we don't know as much as we think we know and that could affect the credibility of other types of technologies that use high pressure," he said.

"It represents just a total failure of that project design. And if this project can fail in this way in an unexplained or even unexplainable kind of way – what does that mean about other types of oil and gas extraction [that] use high pressure injection?"

With so many unanswered questions, protesters are taking to the street outside CNRL headquarters in Calgary.

Company officials turned down our request to speak about the spill.