‘This takes decades’: Banff backcountry paddling off limits due to whirling disease

CALGARY – The detection of a devastating aquatic invasive species in Banff National Park is expected to pour cold water on recreational enthusiasts hoping to get back to nature.

Parks Canada has detected whirling disease in Lake Louise, an iconic locale, famed for its crystal blue water and breathtaking views.

The disease, which has a fatality rate of up to 90 per cent for juvenile trout, salmon and whitefish, was first confirmed in Canada at Johnson Lake in Banff National Park in 2016.

As a result, beginning this spring paddling and the use of large inflatables, along with the use of waders or wading boots while fishing, will be banned at Lake Minnewanka, Bow Lake and Moraine Lake.

Park officials say they are trying to find the best path forward.

“We understand the disappointment that visitors would like to keep recreating on some of these water bodies, but we are trying to find a balance between protection of our sensitive ecosystems as well as finding locations and opportunities for them to continue water body recreation,” said Marie Veillard, the aquatic invasive species project co-ordinator for Lake Louise, Yoho and Kootenay field unit.

Lake Louise itself is considered a recreation area so activities are allowed as long as visitors clean, drain and dry their equipment before use.

“It doesn’t have additional ecological concerns. It doesn’t have species at risk. It’s not slated for a restoration project for species at risk and it doesn’t have necessarily important migratory routes because there’s a fish barrier in it,” she said.

Veillard said whirling disease is extremely difficult to remove from infected waters but there have been some instances in the United States where the life cycle of the parasite has been broken.

“What has been happening in more cases is the fish eventually will develop resistance to the parasite but you do have to have enough fish left in the population to continue reproducing and adapting their genetics over time,” she said in an interview Thursday.

“This takes decades for that to happen.”

Bow Lake and Moraine Lake are classified as preservation zones under the new restrictions. The new rules are likely to stay in place.

“The restrictions that we are implementing right now are part of a zoning framework that is a regional approach and that is being implemented on an ongoing basis so there’s no specific end date to this,” said François Masse, superintendent for Parks Canada’s Lake Louise, Yoho and Kootenays field unit.

“Aquatic invasive species are extremely difficult to remove. Prevention is the most effective way to protect our lakes and rivers.”

Veillard said similar restrictions were put in place in Yoho National Park in 2023 and it has been successful.

“As we haven’t had any new detections in the past few years we’re feeling confident that these restrictions are achieving the results that we are looking for,” she said.

“By creating these restrictions we are able to target the human mediated spread of aquatic invasive species and slow that spread beyond our known location.”

This report by The Canadian Press was first published March 12, 2026.

Note to readers:This is a corrected story. A previous version said the parasite that causes whirling disease was first confirmed in Canada a year ago. In fact, the first case was in 2016.