Photo: Contributed - CN.ca

Opponents of the Northern Gateway pipeline are threatening to turn their sights on CN Rail, as at least one Alberta oil company explores the possibility of transporting oil sands crude to the B.C. coast by rail car.

Sixteen environmental groups signed a letter sent to Canadian National CEO Claude Mongeau this week to express opposition to any plans to ship product from the Alberta oil sands west by rail.

"Unfortunately, ... there are far greater fatality, injury and environmental risks when transporting crude oil by rail than by pipeline," the letter said.

"Should CN decide to try to move forward with its proposal, it would face major opposition and risks to the company. We urge you to stop any forward movement with shipping tar sands oil by rail through British Columbia."

It cites a study last year by the Manhattan Institute, a right-leaning American think tank that has endorsed construction of the Keystone XL pipeline from Canada to the Gulf Coast after comparing the safety and accident statistics of rail, road and pipelines.

Mark Hallman, director of communications for CN Rail, said railways have a solid record in transporting hazardous materials.

"Rail complements pipeline in the movement of crude oil. Both modes are safe and the risk of accidental releases of product is extremely low for both modes of transport, with no appreciable difference considering both spill frequency and size," Hallman said.

The groups, including Greenpeace Canada, West Coast Environmental Law and Sierra Club of BC, cite two 2005 train derailments.

On Aug. 3, 2005, a train derailed west of Edmonton and spilled 800,000 litres of bunker oil and wood preservative into Wabamun Lake. The spill killed birds and fish, polluted the shoreline and forced authorities to truck drinking water into the area for 18 months. Two days later, on Aug. 5, 2005, a derailment near Squamish spilled 40,000 litres of caustic soda into the Cheakamus River, killing half a million fish.

CN pleaded guilty in 2009 to violating federal laws protecting fish and migratory birds and failing to properly remediate a spill, and agreed to pay $1.8 million for both incidents.

An official with the Port of Prince Rupert confirmed that it has had "very preliminary" talks with Nexen Inc., (TSX:NXY) about using trains to bring oil from Alberta to the north coast port city. Discussions began over a year ago, Michael Gurney, manager of corporate communications for the Prince Rupert Port Authority, said Thursday.

"We really want to emphasize that this has not yet even evolved into a project. This is a concept that they are exploring at the port authority," Gurney said.