Heavy rainfall and a washed-out beaver dam are being blamed for Saturday’s train derailment in Burnaby.

Canadian National Railway Company spokesperson Emily Hamer has confirmed the incident that led to three rail cars flipping on their sides is due to dirt being washed away.

“We have determined that heavy rainfall has caused a beaver dam to be washed away, affecting the integrity of the rail bed beneath the track,” Hamer said.

“Reconstruction efforts are under way and we expect the track will be operational later today.”

Just before 11 a.m. on Saturday seven cars left the track as it was transporting a load of coal from the Kootenays.

The Canadian Pacific owned train was being operated by two CN crew members, neither of who were injured.

Hamer said crews worked through the night to remove the railcars and contain the coal that spilled into a creek feeding into Burnaby Lake.

“Cleanup is well under way,” Hamer said. “We are working closely with B.C. Ministry of Environment who is assessing the area.”

Kevin Washbrook, spokesman for a group called Voters Taking Action on Climate Change, said he saw powdered coal leaching into the creek from two overturned cars.

The creek had turned black and nearby signage indicated it's a sensitive fish habitat, he said.

The derailment is a wake-up call to hold back on proposed plans to increase coal export capacity at Neptune Terminals, Washbrook said.

He said that if the Vancouver Fraser Port Authority's plan is approved, coal exports would triple at Neptune in North Vancouver, where city council has called on the authority to conduct a comprehensive health assessment before the expansion.

"The port authority has complete decision-making power over port lands but those decisions have potential impacts for surrounding communities," Washbrook said.

"We've spent a year and a half now on this issue, encouraging the federal government to step in and their response has always been, `Talk to the port authority.' When we raise issues with the port authority about this they say, `It's up to the railways to control the movement of trains."'

Earlier this week, a CN freight train jumped the tracks and caught fire near the village of Plaster Rock, N.B., where 150 people were forced to leave their homes.

The company has said 17 of the train's 122 cars derailed, and some of them were carrying crude oil and propane.

With files from The Canadian Press.