BURNABY, METRO VANCOUVER -- The latest in the string of railway derailments that has Canadians worrying about safety is being blamed on a lowly beaver in Burnaby. Heavy rain this weekend washed out a beaver dam, the washout damaged nearby Canadian National tracks, and a Canadian Pacific train derailed Saturday morning, spilling coal into a protected waterway, CN spokeswoman Emily Hamer said Sunday. The derailment comes as a debate rages over using trains to transport crude oil as an alternative or adjunct to pipelines. Hamer said seven cars of a 152-car train carrying coal went off the CN Rail tracks at around 11 a.m. near Government and Cariboo Roads, north of Burnaby Lake. Four of the cars stayed upright, but three tipped over spilling coal. The train's two crew members were not hurt. "The beaver had built its dam into where our tracks are and erosion caused the dam to collapse which led to the washout. It affected the integrity of our tracks, which led to the derailment," Hamer said. === VIEW MORE PHOTOS HERE, or if you're using a mobile device, tap the story image and swipe. === Otto Langer, retired head of habitat assessment and planning for the federal Fisheries department in B.C., said he's surprised something as minor as a beaver dam could put a railway at risk. "I thought railways were massively engineered structures. I find it amazing that a railway wouldn't be better maintained so a little beaver dam wouldn't be a threat to a railway," Langer said, adding that beaver are common in the Lower Mainland. A local environmental group, Voters Taking Action on Climate Change, also questioned the maintenance of the line. "Given that heavy rains were widely forecast for this weekend, this calls into question how closely CN is monitoring the safety status of rail lines used by heavy and long coal trains," the group said in a statement. The group's director Kevin Washbrook said in an interview that coal trains are very long and very heavy. "If you're going to move more coal trains, there has to be a corresponding increase in vigilance," Washbrook said. "We do increase monitoring when heavy rains are forecast and we did track inspection very recently — within the last couple of days," CN's Hamer said. "We do very regular track inspections for the safety of our crews and the communities they run through." This is the latest in a string of rail accidents, including the one in July in which a train containing crude oil derailed and exploded in Lac-Megantic, Que., killing 47 people. On Tuesday, 17 cars, five of which were carrying crude oil, derailed near Wapske, N.B. It was revealed last week that the B.C. and Alberta governments will study the transport of crude oil via rail if the proposed Northern Gateway pipeline and the Kinder Morgan pipeline expansion don't get the green light. Critics say the concept raises serious environmental and safety issues. Burnaby Mayor Derek Corrigan said it is fortunate that the derailment didn't occur in a more populated area where people could have been injured and that the train was carrying coal and not something flammable like oil or bitumen.

He said Burnaby has been pressing the federal government to tell the city what is being transported through Burnaby so that it can plans for rail accidents. "We have no idea (what's being transported through Burnaby) and you can imagine how that makes me feel, knowing that it's going to be our RCMP officers and our fire department that attend," Corrigan said. "If they don't know what they're dealing with, then how do we react and how do we look after the public? We need to be informed if there are toxic and dangerous substances." He says Burnaby isn't getting any response and the federal government is increasingly letting the railways regulate themselves. "The federal government keeps dropping expertise in these areas and depending wholly on these companies to provide the expertise. If there is an accident, there isn't even the capacity on the part of the government to evaluate the damage — they have the companies do that themselves. It has reached the point of absurdity," Corrigan said. Hamer said that some of the coal spilled into a waterway, but she could not say how much. She said CN and CP crews were assessing the environmental impact Sunday. "Clean up is well underway and track reconstruction is also underway," Hamer said. The track was expected to reopen late Sunday. CN is working with the B.C. Ministry of Environment on the cleanup, Hamer said. At the creek, which feeds into Burnaby Lake, there is a sign noting that the waterway is considered a sensitive fish and wildlife habitat, and that the area is protected by Fisheries and Oceans Canada. Langer, who has been involved in a number of coal cases in court as an expert, said a lot of work has been done to restore that watershed, and that salmon have returned into the Burnaby Lake system. He said that although coal is not particularly dangerous as a chemical pollutant, it is a physical pollutant that harms fish when they breathe through their gills. "Coal is fairly inert, but it's a sharp particle. You don't want sediment dumped into a stream and coal is probably especially bad because it's fairly light and will wash down the stream. It will contaminate and pollute fish habitat and it will clog up the gravel in a stream. "It will affect the invertebrates and the fish," Langer said. "It's a little bit like broken up rock or glass-type fragments, so when the fish breathe water through their mouth or their gills, if sharp particulate matter gets into their gills it does damage." It's the same reason people are concerned about breathing in coal dust. "That type of dust does horrible things to your lungs as the coal miners will tell you. It's a light material so it drifts quite easily and it will move around in the water quite easily," Langer said. Langer said the beavers who lost their dam in the heavy rain should survive. "Hopefully they can keep the (coal dust) out of their lungs because they breathe out of the air, they don't breathe in water. They have to stick their nose out of the water. Hopefully it won't irritate their fur too much," Langer said, adding that the winter rains should help flush away a lot of the coal dust.