Canmore's Cougar Creek flood aftermath visible 100 days later

CBC's Carolyn Dunn recently spent three days touring Canmore and Kananaskis in Albertato see the aftermath of June's flood and she spoke on the Calgary Eyeopener this morning about what she learned.

• Listen to her full interview below:

Professor JohnPomeroy,Canada Research Chair in Water Resources andClimate Changewith the University of Calgary's BiogeoscienceInstitute, took the seasoned reporterup in a helicopter to survey the damage. He says the changes to the landscape are significant.

• Alberta Flood: 100 Days Later
• Alberta floods: a look back at the first 48 hours

"A lot of the mountain erosion proceeded very, very rapidly during the flood.... I think when people go in here andstart hiking and really see thelandscape and detail they'll notice that they don't recognize their old trails and certainly they won't recognizetheir stream crossings," he said.

The biggest reason why Cougar Creek flooded was the amount of precipitation that hit June 20.

"Environment Canada had forecast about 150 millimetres of rain andthat in itself is just a pretty big rain event to say the least. Butthink about this,it turns out well over 250 millimetres of rain actually fell.Then a metre of snow melted in a really short period of time, adding hundreds of millimetres more to the mix and that's where that sheer volume of water comes from," saidDunn.

Pomeroysays the video his university students shot of the flooding streams demonstrated the river's power.

"What's evident from there is it's not just water moving down. These are boulders, these are full sized trees, lots of sediment with it and so all that's doing far more damage than the water can itself," he said.

Debriscreateda 'ticking bomb'

"It's now completely filled with rubble, with trees. The trees, we saw them in some places peeled, literally skinned going up 20, 30 feet above the ground from boulders passing them by and ripping them off."

Pomeroysays all this debris has made some areas of vulnerability.

"Well there is lots of material that's been mobilized now and already moved down the mountain and it's sitting there waiting for the next rain to move it further down, so the mountains are in this sensea bit like a ticking bomb right now," he said.

Dunn saysCanmoreis planning to put in some mitigation measuresbefore next spring.

"A couple of things they're looking at is maybe putting a super heavy industrial net up at the very top of Cougar Creek to catch the big debris like trees and boulders before they tumble down and cause a problem and also they're considering something called a gabion mattress, which is really a wire mesh linerthat would go along the bottom of the creek bed to stabilize it," she said.

Paul and Marion Kutzer check on their Cougar Creek home almost every day after the flood ripped the foundation out from under the back half of their house. The floodwaters severely damaged 44 homes along the creek, andnow they are not safe to live in.

"Well it's been hell, that's all Ican say about it," said Paul.

Report outlined 'catastrophic flood potential'

What the Kutzers and others didn't know when they bought the property is that a 1980 engineering report concluded among other things that the area was not ideally suitable for development because of its "catastrophic flood potential."

"We felt that because it was approved with certain mitigating measures that they would be followed, but they weren't unfortunately," said Paul.

Universityof Calgarygeoscientist Gerry Osborne says the problem is previous studies treated Cougar Creek as a regular riverand notan alluvial fan which carries debris and sediment, often migrating from side to side.

"It's another example of development pressures [trumping]hazard potentialin [the]growing town of Canmore," he said.

CanmoreMayorJohn Borrowmansays lessons have been learned.

"We're gonna have to step back and look at how we plan land use and how we give development approval," he said.

An important step as development plans for several other Canmore creeks also on alluvial fans move ahead.