Frigid temperatures, plenty of demand so why is Winnipeg's river skating trail at risk?

Winterusually means a skate, walk or run on the river for thousands of Winnipeggers.

The denizens of this city have learned to embrace sub-zero temperatures by strapping on their skatesfor a sprint on the frozen Red or Assiniboine rivers.

But this favourite pastime may not be an option for the first winter in nearly 20 years despite the weather being cold enough, and the tens of thousands waiting to once againstroll, skate, run or maybe even bikedownthe frozen rivers.

So what gives?

It has a lot to do with an unusual fall flood, followed bydroppingwater levels and unstable ice.

Conditions this winter are unprecedented, says Jay Doering, a civil engineering professor at the University of Manitoba and a flooding expert.

Ice bound to break

An unusually wet fall saturated the ground and broughtthe Red River to a levelhigher thanany fall on record.

The water level on the Red reached as high as 17.3 feet at James Avenue on Oct. 23. It's fallen dramatically since then to undersevenfeet James, as of Friday but that's still well above the normalice level of around zero feetJames.

Theriver began freezing, though, at an unusually high level. That ice has frozeninto chunks, says CBC meteorologist John Sauder.

"It's almost like broken glass sitting on top of the river," he said.

As the river level has dropped, a gap has formed between those solid blocks of surface iceand the water air pockets that cannot last.

"The ice sheet is clearly going to have to adjust," Doering said."It's going to have to break, it's going to have to crack, and I don't know where those cracks are going to appear."

Normally, the water stays at asteady level through the winter. This year, the water level is likely to continue dropping, he saysprobably until March.

"How that ice sheet adjusts to that drop?It's not something I'm comfortable predicting," he said.

He also expects the riverbank ice to break, with the river narrowingas it drains.

"I don't know, or can't say, that it's going to break off cleanly, so I have concerns about where fissures might open up and what might happen as the ice sheet attempts to crack and refreeze."

He stresses, though, that the decision on whether or not to open a river trail isn't his.

That call will rest with staff atThe Forks, who are monitoring the river every dayto ensure safety.

The loss of the skating trail would be a significantblow to The Forks800,000 people used the icy trail last year, according to officials.

Flowing fast

Another complication for the trail this yearis the speed atwhich the water is flowing.

The more water you have in a constrained space, the faster it moves, says Nora Casson, a Canada Research Chair inEnvironmental Influences on Water Quality.

Because of the speed at which theRed River has been flowing, it's been difficult for the water to freeze this year.

"The river iskind of like a pipe, right?It's fixed in size," saidCasson, also a geography professor at the University of Winnipeg. "If you are trying to force more water through the same shape, it'll move more quickly."

The outlook for freezing has been even further complicated by fluctuating temperatures, which have swung fromabove tobelow freezing like a pendulum, she says.

In spite of all the uncertainty, The Forks isn't giving up onthe river trail.

Every year is different. Last year, the trail stretched 8.6 kilometres long and operatedfor a record-breaking 75 days. By contrast, it was open for just33 daysin 2016-17.

"Ultimately, we're always at Mother Nature's whim when it comes to building the river trail," said Larissa Peck, manager of marketing and communications at The Forks.

If the trail doesn't openat all, it would be the first time that's happened since 2000. But Peck says it'spremature to sound the death knell for this season.

"We still feel we have a few weeks before we canmake that call."

Last season, the skating rink on the Assiniboine at The Forks dockopened on Dec. 28, but the first section of thetrail didn't officially open until Jan. 4. That was on par with previous years, Forks officials said at that point.

Peck says The Forks is speaking with theorganizers of various winter events on the river, like the outdoor curling bonspiel, to ensure those events can go ahead even without ariver trail.

If need be, the popular warming huts wouldpop up elsewhere, and The Forks would expand its on-land skating options.

Casson said climate change shouldn't necessarily be blamed for individual weather events,but the trend of intense stormssuch as a freak Thanksgiving storm that pummelled trees and power linesand winters that are less consistently coldisn't going away.

"When we think about the types of recreational activities that we enjoy during winter, like skating at The Forks, those things are not looking good for the future."