The company said that on the afternoon of July 15, it discovered an emulsion leak from a pipeline within its Long Lake operations.

The Alberta Energy Regulator (AER) is responding to a Nexen pipeline failure located approximately 36 kilometers south east of Fort McMurray. Kyle Glennie, a senior Nexen communications adviser, explained the uncertainty of the spill’s pipeline production disruption and the need for further investigation.

Alberta Premier Rachel Notley said Friday that pipelines are still the best way to transport oil and gas despite this week’s leak.

Nexen said in a statement that “all necessary steps and precautions have been taken” and the company will protect the health and safety of all employees, contractors, the public and the environment.

The Nexen spill is one of the bigger ones in recent years. Both Nexen and Murchland said that it was too early to know the cause of the spill.

The spill coincides with a meeting of Canadian premiers in St. John’s N.L., at which energy issues, including pipeline construction, are expected to be discussed.

Nexen says the site is under control but the emulsion has apparently spilled into some muskeg.

Precedent for the types of punishments handed out to companies responsible for major oil spills is evident in decisions from the last few years. Yet, the amount of oil spilled is considered the largest in North American history, exceeding the 2010 Enbridge Michigan spill by 11,418 barrels, over half the total amount spilled by Enbridge.

Greenpeace, meanwhile, said the spill was just the latest evidence of environmental risks posed by the controversial practice of extracting oil from tar sands.

According to CTV News, Long Lake is roughly 20 miles southeast of Fort McMurray, and uses steam to heat underground oil sands, which then rise through the ground.