VANCOUVER - A forestry expert says the B.C. government needs to take "urgent" action to prevent flooding in some watersheds ravaged by the mountain pine beetle epidemic.
Younes Alila, a forestry professor at the University of B.C., said Monday that flat-terrained watersheds that are covered mostly by pine and are clearcut to remove dead trees are most at risk to cause flooding.
He said the issue should raise alarm bells.
"Therefore this calls for the authorities within British Columbia to order detailed investigations of the potential for flooding of the Fraser River that may be related to the beetle," Alila told reporters in a conference call.
"That is somewhat urgent because the decision on how much we salvage logs could be a deciding factor on the potential for flooding in the Fraser River."
Alila was basing his comments on a study he conducted for the Forest Practices Board, an independent watchdog for sound forest practices.
An infestation of the mountain pine beetle has ravaged B.C. forests and covers about 8.5 million hectares, an area more than twice as large as Vancouver Island.
It's estimated that by the time the infestation runs its course in 2013, 80 per cent of the B.C. Interior's pine will be dead.
"The beetle is affecting a very large area of British Columbia," Alila said.
"We think, out of this piece of work, that the most heavily affected area in terms of increase of flood risk would be the upper Fraser (River) area, the Nechako area, and the Fraser plateau areas."
Alila used the Baker Creek watershed, west of Quesnel, for his research because it has similar characteristics to those that are most at risk for flooding.
He said his work shows the pine-beetle epidemic could increase stream flow by 60 per cent in Baker Creek.
When clearcut salvage logging of the beetle-infested trees is added, the stream flow could increase to 92 per cent, Alila said.
That's because melting snow is no longer intercepted by trees that once stood in the forest. And trees that lie dead on the forest floor after they've been killed by pine beetles don't hold the same amount of water compared to when they were alive.
The result is a greater water flow into streams and a higher risk of flooding.
Alila said his research shows floods that used to occur every 20 years are now likely every three to five years.
Studies done in Colorado suggest it could take up to 60 years to replenish conditions in watersheds, increasing the potential of flooding even more, he said.
Bruce Fraser, chairman of the Forest Practices Board, said watershed assessments that would help develop strategies to protect drinking water, preserve fish habitats and prevent flooding are no longer required under provincial legislation.
"We see (assessments) as being a highly prudent thing to include in the professional assessment of watershed risks," Fraser said.
In the past, bridges and culverts were built on the basis of assumed flood risks, he said.
Forests Minister Rich Coleman said the government requires forestry companies to put watershed assessments into their forest plans.
"When they're working in a watershed they're supposed to do a watershed assessment with a hydrologist and determine how best to cut and not affect the watershed," Coleman said.
But Rob Duncan, spokesman for the B.C. branch of the Sierra Club, said assessments in beetle-attacked areas are only voluntary.
"It's not a mandatory requirement but it's a good suggestion that should be legislated."
Steve Chatwin, another spokesman for the Forest Practices Board, said the study is not suggesting that clearcutting to deal with the pine beetle should be curtailed because dead trees would pose a forest-fire hazard.
"What it is is a heads up to all of the professional community about the fact that the decisions they make with respect to salvage logging and replanting have to be balanced against the decisions they make to conserve the watershed hydrology," Chatwin said.
