Banff, Canmore residents watching as rain falls, river rise

Heavy rains predicted for mountain communities The heaviest rain was predicted for mountain communities, bringing back memories of 2013. Kevin Green reports

Late Monday,  the province lowered the threat level  for flooding in the mountain region from a warning to a watch.

A warning means a flood appears imminent, while a watch means that the conditions are favourable for it to occur.

BANFF

While that’s considered a positive development, Banff fire chief Silvio Adamo said it hasn’t changed the town's plans to secure the river banks.

“What we've learned from 2013 is be prepared and deploy early," Adamo said. "So even with being downgraded to watch, the forecasting numbers that we're seeing still warrant taking these types of precautions. And we'd much rather be preventative than reactive.”

Banff firefighters spent most of Monday rolling out long orange tubes known as “Tiger Dams” along the edge of the river.

They can be filled with water to create a nearly 1.2 meter  (four foot) high wall to prevent flooding. Additionally, the town of Banff warned residents living in the lowest lying areas of the town in a complex along Birch Ave. to be prepared to evacuate if the river rises.

“We went door to door yesterday afternoon and touched base with all 130 units in these two complexes, (on Birch Ave) just to give them preparedness messaging, " said Adamo.

Banff has also closed some trails near the river and is advising residents and tourists to avoid its banks.

CANMORE

The Town of Canmore is monitoring groundwater levels, steep creeks and the Bow River. Town officials said issues are expected in low lying areas if the town receives in excess of 50 millimetres of rain.

The existing flood mitigation work along Cougar Creek is expected to ensure the flow in the channel is maintained.

The pathway under the Bow River Bridge in Canmore was closed last week. Additional trails will be closed in Canmore along the Bow River if rising water levels present a safety risk.

John Pomeroy, a university of Saskatchewan hydrologist living in Canmore, said there are some key differences between this weather event and the one that led to the 2013 floods.

Primarily he cited the temperature in higher elevations.

"The predicted 150 millimeters of precipitation is a lot but in the high mountains, a lot of that could fall as snow. That is going to have a tremendous difference on the ability of that system to generate flooding." said Pomeroy.

"The snowpack building up in the mountains will stop the snowmelt that's been occurring. It’s been releasing 40 to 50 millimetres of water per day, on to the high mountains. It will stop that, and it will build up the snowpack instead, and then it will melt more slowly over the next few days."

But Pomeroy warned that the difference between a building snowpack and slow melt, and a fast, flood-inducing downpour was only a matter of a few degrees.

"If the weather were to warm up in the high elevations, just a couple of degrees, then we would have rain on snow instead of snowfall forming  in the high mountains," said Pomeroy.

"Rain on snow is the worst case scenario for sure. This is what happened in British Columbia in the Fraser Valley in November. And it occurred in the mountains above Calgary in 2013."

While the Bow River is high through Canmore, the majority of the 2013 floods were generated from Cougar Creek, which has since undergone a massive remediation.

Monday it was devoid of water, giving many Canmore residents a sense of optimism.

“I'm pretty sure you know, it has to be pretty bad for them to breach them now that you know, I just think that they probably done as much as they can," said Canmore resident Brad Townsend who said while he’s personally not too worried he knows the memories of 2013 are still strong for many in the mountain town.

“I'm thinking a lot of people are pretty anxious when it starts to rain like this, because last time they predicted about the same amount of rain, and it turned out to be three times. You know, boom, it all came down the valley.”

EXSHAW

In 2013 Exshaw residents were slammed as three creeks overflowed their banks and submerged many of the homes in the community of 449 people.

Since then the Municipal District of Bighorn has upgraded all three creeks to high levels of flood protection. Both Exshaw Creek and Jura Creek are able to withstand a one in 500 year flood event, while Heart Creek has been upgraded to one in 300 year status.

The MD’s CAO Robert Ellis was optimistic that Exshaw will be spared any major flooding this year.

“The forecast that we've heard, the amount of the water is nowhere near the precipitation that we received back in 2013. And with the amount of mitigation that we've done for the creeks that were involved, that affected obviously the MD of Bighorn, we don't see that type of overland flooding occurring here during this event," said Ellis, who said while overland flooding is unlikely there is a high risk of groundwater flooding in some parts of the community.

“We've always had some flooding in east Exshaw. It's just that it's one of the lowest points in the community. The water does come and seep into basements, we did have an event in 2020, where the water actually did rise with the pressure from the Bow River and our aquifer became full. I don't know if we're going to see that same type of thing. But basements will likely be wet.”

East Exshaw resident Kelly Suchan is one of the residents whose basement flooded in 2020, even after the creek remediation was complete.

Monday he was installing five sump pumps in his home to try and ward off any flood damage this year.

“I'd rather be doing this now than at two or three in the morning. So I'm going to get ready," said Suchan.

"If it happens, it happens. If it doesn't well, then you just wrap everything up and put it away and wait till next year."