Multi-year project in Banff National Park aims to restore river altered by dam decades ago

Parks Canada is working on a multi-year project to reshape the Cascade Creek in Banff National Park after it was dramatically altered by a dam built in 1941.

"Dams are often highlighted as one of the future green energy producers. But they do have significant effects, not only on fish but on how streams move and meander over time," said resource conservation manager Bill Hunt.

Hunt said the river system was historically the same size as Spray River, but part of the creek dried up to just a trickle. During the 2013 flood some of the sections were briefly filled with flowing water again, leaving behind metre-high silt deposits.

"We're hoping that what we do here is kind of a high-profile demonstration project," said Hunt, with lessons that could hopefully be applied in other areas.

"This was a large river system. Like it would have been quite exciting in a canoe or kayak and now we're down to a small trickle and what we're hoping to show through this as well is that even though the flows are reduced, with careful design work we can still restore viable fisheries habitat."

Parks Canada is working with TransAlta which owns the Cascade plant to restore the river's natural flow and bring back native fish.

The power plant is the only one to be located within a national park in Canada, generating 52,000megawatt hours a year according to TransAlta's website.

That means creating new pools, rocky steps and riffles to create healthy habitats for plants and both aquatic and terrestrial wildlife.

"Once we get the habitat restored and have good wintering pools and good spawning habitats, we'll look to bring native fish back to the system," Hunt said.

For now, they're working on a 250-metre test section that they'll assess before expanding to other areas, andin two years they hope to have connected a nine-kilometre stretch between the Minnewanka Reservoir and the Bow River.

Parks has removed thousands of non-native brook trout from the area and plans to re-introduce native species like cuthroat and bull trout within a few years.

Hunt said the design features will allow fish to enter the Bow, but will prevent them from travelling up the Bow back into the Cascade.

The channels will also allow for the river to be widened in the case of flooding.

They've already restored a stretch along Legacy Trail between Banff and Canmore.

"That was a dry grassy ditch," said Hunt."Because of the profile of this stream along the Legacy Trail it's a really good opportunity for people to learn about habitat restoration."

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With files from Dave Gilson.