The cause of the train derailment that resulted in the spill of 41,000 litres of corrosive sodium hydroxide into the Cheakamus River is still unknown but the effects could be felt for decades.
"We dont want to overestimate it, but lets say a very significant percentage of the fish population, all ages, all species, was wiped out," said Brian Clark, the provincial incident commander and regional manager of environmental stewardship for the Ministry of the Environment, from an emergency response centre that was set up in the area of Fridays spill.
"It could be 90 per cent (of fish), it could be 70 per cent. Its definitely a significant portion.
"Its going to take a long time to recover."
Early estimates on how long fish populations could take to recover vary from about 10 to 25 years, but a more detailed assessment could be made by next week.
According to Clark, the spill occurred just one week after local streamkeepers and Fisheries and Oceans Canada completed a comprehensive sampling of fish species along the river. Those streamkeepers returned to the same locations just days after the spill, and will use the same sampling methods to help determine what was lost.
"We have a really good idea of what was in the river a week before the event, and the next couple of days well be sampling the same locations using the same techniques, and thats going to give us a pretty accurate before and after picture," said Clark.
The derailment occurred at approximately 7:15 a.m. on Friday, Aug. 5 on a section of track in Cheakamus Canyon, north of Squamish. One of the nine overturned cars spilled most of its contents of sodium hydroxide into the river. The spill left countless numbers of dead fish strewn along the banks of the river, killing almost everything in its path before being diluted and transformed further downriver.
CN Rail and Transport Canada are still investigating the cause of the derailment of nine rail cars en route to Prince George, although a federal accident investigator has ruled out the possibility that there was something wrong with the tracks themselves. Squamish Valley residents suggested to the Globe and Mail that the length of the 144-car train might be responsible. B.C. Rail seldom ran trains longer than 90 cars on that section of track, they said. Representatives from railway workers unions have backed those claims and are asking the federal government for a full review.
CN Rail, which purchased B.C. Rail in 2004, has discounted that claim by suggesting operations were within industry standards.
According to Clark the cleanup has been successful, and the sodium hydroxide in the river has either been diluted or combined with other elements to form stable compounds through natural processes. By Sunday there was no longer any risk to the fish, to recreational users, or to residents along the river.