Prince George has been given the go-ahead to pump warm water into the Nechako River with the aim of loosening an ice jam that has caused widespread flooding in the city for five weeks.
Clean discharge water heated to 15 degrees from steam plants belonging to Canfor pulp mills on the northern outskirts of the city will be pumped into the river as soon as possible, said city spokesman Don Schaffer.
Approval for the plan came from the Provincial Emergency Program, he said. The estimated cost for the project is $500,000.
He said that the temperature was only four degrees warmer than the current temperature of the river and would therefore have little impact on resident sturgeon and bull trout.
A second plan, to run an amphibious excavator - a digging machine that is adapted to work in water - that would sit in the river, carve out ice, and move it to a stretch of open water on the nearby Fraser River was also given approval by the PEP, Mr. Schaffer said.
The unseasonably warm temperatures of the past week have resulted in open water on the Fraser River, creating an opportunity that did not exist earlier to move ice out of the Nechako.
"Several hundred metres of melted water has opened up on the Fraser and there is an indication from ice experts that using a water-based excavator is now feasible. Before it just wasn't safe," he said.
Mr. Schaffer said city and provincial engineers are relieved "to now be proactive" in combatting the six-kilometre-long ice jam, which runs three metres deep in some places.
"It's exciting to be able to do something. We've been told for so long to leave it alone because we didn't have a place for the ice to go. We hope to see dramatic change once we get under way," he said.
Around 20 homes and the same number of businesses are under evacuation orders, and 100 businesses and homes remain under evacuation notice.
Meanwhile, a local academic says the mountain pine beetle has had a role to play in the excess water that has caused the ice jam this winter.
Stephan Dery, an environmental science professor at the University of Northern British Columbia, said the decade-long beetle infestation is partly to blame for Prince George's ice-jam problem because it has affected the way water flows into local rivers and lakes in the absence of millions of living trees.
Historically, lodgepole pines used tonnes of rain and snow for nourishment year-round.
But with between 60 and 80 per cent of mature lodgepole forests on the mountains surrounding Prince George now killed off by the beetle, more water has ended up in the Nechako from the region's rivers and lakes.
Prof. Dery said ecologically sensitive tree canopies are also dying, and snow and water that once accumulated above the forest floor falls straight down, adding to the high groundwater levels.
"We had record snow and [spring melt]last winter and spring, and high water flows all summer. That, along with the cold snap, started the ice jam. So the pine beetle is enhancing the flood situation, though it is only one cause." He said the ice jam, while creating a crisis for the city, could also provide an academic opportunity to study the fallout of the pine-beetle epidemic.
"I'm just beginning to investigate the possibilities of this with my students," he said.