Fatal landslide blamed on old logging road raises fears about hidden risks near Canada's highways

At first, Brenda Diederichs only heard it — the rumbling and cracking. As boulders and mud dropped 650 metres down a steep valley slope toward the highway where she was hunkered in her car, trees snapped like pencils.

Diederichs was one of dozens of people trapped in that valley on the morning of Nov. 15, 2021, when an earlier landslide had blocked Highway 99, about 40 kilometres southwest of Lillooet, B.C.

Her son, who was travelling just ahead of her, had gotten out of his vehicle to run and help others after the first landslide. He urged his mother to get back in her car for safety. As she scrambled back to her car, they made eye contact.

Then, suddenly, a second six-metre-high wave of debris swept across the highway.

"It can happen so fast; I don't know how people could prepare to avoid those situations," said Diederichs.

Five people were confirmed dead, among them her 36-year-old son, Brett Diederichs, whose body still hasn't been found. 

Diederichs said it was infuriating to learn that the fatal landslide she survived was likely caused by land-management issues around an old logging road, and may have been preventable.

"I got angrier and angrier the more I thought about it," said Diederichs.

"Why were we allowed to be on that highway that day? There should have been some caution used. Putting all of those people in danger, that made me furious."

As Diederichs and the others drove down Highway 99, also called Duffey Lake Road, that day, a thin swathe of forest curtained what was behind — a steep slope made unstable by logging activity that dates back decades.

Engineers and hydrologists say the underlying cause of the landslide was unenforced land-management regulations, a legacy of historical logging that left unstable land with dangerous drainage invisible above the highway.

And the tragedy points to much larger land-management issues with the close to 1.5 million kilometres of logging, mining and oil exploration or so-called resource roads snaked across Canada — enough road to circle the Earth 37 times.

Often the roads are not deactivated properly after the logging or mining activity, experts say, creating drainage problems and other hazards. The dangers are even greater in steep-sloped areas.

B.C.'s Forest Practices Board has warned the province repeatedly about the inconsistent and inaccurate information on forest service roads. In a November 2020 report, the B.C. Auditor General rapped the province for not managing the safety and environmental risks on such roads, thus increasing the risk to road users.