Creek in Banff that was reduced to a trickle by Minnewanka dam almost restored

A multi-year project is nearing completion that aims to restore a creek in Banff National Park that has been reduced over the decades to a mere trickle. 

Cascade Creek is a nine-kilometre stretch of stream that flows from the Lake Minnewanka reservoir. It used to flow all the way south to the Bow River, but in the years since the dam was built in 1941, the stream has slowly dried up and the old river bed filled with fine sediment.

The creek’s natural habitat also suffered from the introduction of non-native fish species, particularly brook trout, which have been able to out-compete the native westslope cutthroat trout, said Parks Canada ecologist Helen Irwin, who is leading the project.

“The Cascade Creek restoration project is essentially trying to bring the stream back to life, and restore it as a home for westslope cutthroat trout, which is now a threatened species at risk,” she said.

“If you look at a map of what the westslope cutthroat trout range used to be and what it is now, it is just a tiny portion of it,” she said.

The image on the left shows the creek bed prior to restoration, and the image on the right shows the same spot after restoration work. (Parks Canada)

The restoration project began in 2010, but the catastrophic flooding in 2013 actually pushed things ahead faster than anticipated.

“A sudden release of floodwater from the Minnewanka dam during the flood of 2013, followed the old Cascade river bed and scoured away years of accumulated sediment within a few days,” the Parks Canada website says.

In the wake of the flood, Parks Canada, TransAlta and the federal Department of Fisheries and Oceans jointly developed a plan to restore the creek and reconnect it with the Bow River.

Crews have now replaced pipes and culverts to accommodate increased flows and installed an upstream fish barrier to prevent non-native fish from re-entering the stream channel.

“We’ve also been able to plant approximately 2,500 native trees and shrubs to help create healthy stream bank habitat along portions of the restored channel,” Irwin said.

Enough progress has been made that Parks Canada scientists are aiming to start re-introducing the westslope cutthroat trout as early as next year.

Cascade Creek had been reduced to a trickle over the decades since the Lake Minnewanka reservoir was built in 1941. (Dave Gilson/CBC)

Irwin says that the restoration work is complex and takes years to achieve.

“We’ve been able to make significant progress and we’re really excited about the next steps in our project,” she said. 

“What we would really like people to take away from it, is that it is possible to restore freshwater ecosystems and to recover species at risk.”

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