The current drought in many parts of British Columbia is causing some rivers in the province’s northern interior to reach their driest levels in years in mid-October.
In Prince George, unusually low waters have locals worried.
Harriet Schoeter moved to this northern British Columbia town 60 years ago and loves walking along the shore where the Fraser and Nechako rivers meet.
This week, the water was so low I could almost walk across.
“I’ve never seen it so low,” he said. “It was short before, but not like this.”
Wayne Salewski of the Nechako Environmental and Water Management Society said that for this time of year, the river is actually at its driest in decades.
“It’s terribly low, incredibly low,” Salewski said, standing on the dry river bottom at the confluence of the two Prince George rivers. “Everything is going to pay the price for that.
“Our streams are dry right now… We need to hold the water in place.”
Shallower, warmer waters will harm salmon, sturgeon and people whose livelihoods depend on healthy rivers, he said.
Now, Salewski’s nonprofit is seeking help from Canada’s best-known builders: beavers to stem water loss in tributaries.
‘Nature’s Engineers’
According to data from Environment and Climate Change Canada, the Fraser River near Prince George is at its lowest level in 17 years this week, and almost a third below the historical average for October.
The Nechako River, which flows into the Fraser from a reservoir west of the city, is at its lowest level for this time of year since records have been kept.
Salewski asked engineers at the University of Northern British Columbia to help plan beaver analogue dams (BDAs), a promising solution that is common in Washington, Idaho and other US states.
Sometimes also known as artificial jams, the idea is to simulate the wooden and mud dams of flat-tailed rodents to retain moisture from tributaries in small ponds.
“Beavers are nature’s engineers,” said Mauricio Dziedzic, chair of engineering at UNBC. “They tend to build dams that hold for quite a long time.”
He assists the Salewski society in the technical aspects of beaver-style construction. Thanks to their sharp teeth, he said, beavers cut wood to start a new dam, cross branches in a stream, add mud and then compact it with their flat tails.
“They use their tails to hit it and make it almost waterproof,” he said.
“A man-made structure to look and function similarly: by keeping water behind the dam, groundwater is recharged. [and] cause soil moisture to increase.”
‘A more resilient type of waterway’
BC already has several pilot projects of this type. Researchers from the BC Wildlife Federation (BCWF) and the Nicola Valley Institute of Technology installed nearly a dozen BDAs in a stream near Merritt, BC, earlier this year.
The federation plans to build at least 100 more in the interior and north of the province, including the Nechako tributaries.
By driving vertical wooden posts into the stream bed and weaving them with debris like logs, evergreen branches and mud, their hope is that beavers will take over their upkeep.
“It’s basically a starter kit for a beaver,” explained Neil Fletcher, BCTF conservation director. “Can we encourage the beavers to return to the land base and help retain that water?
“Beaver-like dams can be part of post-fire recovery, as well as responding to drought and climate change.”
Last April, the Habitat Conservation Trust offered BCWF $100,000 to test woven wood dams across British Columbia.
Fletcher said a key area of study is how BDAs impact fish. But he said U.S. evidence suggests salmon can often migrate past beaver dams or take advantage of their ponds.
Salewski said the low costs of artificial beaver dams have great appeal, especially if the beavers themselves can take care of their maintenance.
“Basically, a beaver analogue dam is building the landscape for beavers to move into in 10 to 15 years,” he told Breaking:.
“This idea… is really trying to work towards wetland corridors, to create this new mosaic and build a more resilient type of waterway here.”
