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Pemberton knew landslide risk

Environment Ministry looking at ongoing monitoring of Meager



Pemberton knew the risks a landslide could pose.

That's according to a report that the Squamish-Lillooet Regional District received in 2008 titled, "Hazard and risk from large landslides from Mount Meager volcano" that was commissioned by Cordilleran Geoscience in Squamish, B.C.

The report, written by geoscientists Pierre Friele, Matthias Jakob and John Clague and delivered to the regional district, warned of a "very high" landslide hazard that would create "complete destruction" over hundreds of square kilometres, creating a high risk of loss-of-life in the Pemberton Valley.

"In the absence of tolerable risk thresholds at the provincial or local government level, we compared the existing landslide risk faced by residents of Pemberton Valley with risk acceptance standards developed in Hong Kong, Australia and under interim use by the District of North Vancouver," the report reads.

According to those standards, existing risk faced by people living in the Lillooet River valley upstream of Lillooet Lake, is considered "unacceptable."

The geoscientists' fears of a major landslide were realized last Friday, when the second biggest landslide in Canadian history descended 2,000 metres from the summit of Mount Meager and created a 40 million cubic metre debris flow. It formed a natural dam at Meager Creek that backed 3 million cubic metres of water behind it.

The water ultimately flowed out through a 30-metre incision in the dam but there are nevertheless ongoing concerns about safety, owing to a debris flow that could carry logs, mud and increased water down the Lillooet River and into the Pemberton Valley.

Pemberton Mayor Jordan Sturdy said the geoscientists gave local authorities an "unsolicited report" that was "plopped" on an SLRD board agenda and didn't give a lot of attention to risk management.

"I'm not sure that these people were experts in risk tolerance or risk management, so much as these are geoscientists that published this paper," he said in an interview.

Sturdy went on to say that authorities looked at putting together an early warning system that would monitor slide activity at Mount Meager and alert residents about a slide before it happens. They didn't go forward with it when they looked at the Mount Meager area and realized it doesn't have any hydro access or telecommunications, making a warning system an expensive proposition.

Instead the village has posted the report on its website and posts an annual public notice on the hazards posed by a slide at Mount Meager.

"The probability of an event is high, it's inevitable, every mountain range falls down and that one's a particularly dynamic one," Sturdy said. "But the chance of an event that is going to flow as far as settled area is pretty darn low."

That statement conflicts with what's written in the report. The geoscientists state that the severity of the slide hazard is "high" and that "associated risk of loss-of-life in the Pemberton Valley is high." They recommend a warning system as the "minimum requirement for responsible long-term hazard and risk management."

B.C. Environment Minister Barry Penner visited the slide area on Tuesday and said his ministry is looking at a monitoring program that would gather geoscientists from various Canadian universities to monitor Mount Meager and gather recommendations on what they should do to minimize further impacts.

"There's a possibility of a partnership between some leading universities and the Ministry of Environment to develop a world-class monitoring effort to give us the best information possible," Penner said.

This wouldn't be the first time that governments have looked at increased monitoring in the Mount Meager area. Following on the geoscientists' 2008 report, officials with the Village of Pemberton looked at putting in early warning devices to alert them of landslides on the mountain.

It is unclear whether those devices were ever installed, but Pemberton residents were not notified of the most recent slide until it happened.

Penner went on to say that Mount Meager remains unstable. He said certain parts of the mountain appear "precarious" and that there's "continuing movement" near the summit.

"It appears the mountain peak continues to be unstable and dynamic," he said. "In fact, according to our geomorphologist, he said that there were pieces missing today that he took pictures of 36 to 40 hours ago, so more pieces have come down."