Canada's mountain lakes fed by glaciers are losing their dazzling blue, documentary shows

A new short documentary filmed in Alberta's Banff National Park and British Columbia's Yoho National Park seeks to capture the impact of climate change on mountain lakes. 

The documentary, called Losing Blue, was shot at 10 different alpine lakes including Peyto Lake, Moraine Lake and Lake Louise from 2020 to 2023.

"This film is basically about an endangered colour and what does it mean to lose that?" said director Leanne Allison. 

The documentary is told through a cinematic poem, looking to create an emotional connection to the lakes' endangered colour. 

"All lakes are born through glaciation and volcanic activity and things like that," Allison said. "All lakes eventually fill with sediment and die."

"I felt like we had a lot more in common with lakes than I ever expected."

The alpine lakes present stunning blue colours through particles from melted glaciers. Since those are shrinking, the lakes are showing the impacts of climate change. 

"That classic Peyto Lake turquoise or Lake Louise turquoise, people come from all around the world to see those lakes and that colour, and that sort of brilliant, almost glowing quality that the lakes have can be attributed to this (glacial flour)," said Janet Fischer science adviser for Losing Blue.

"Glacial flour, this finely ground rock dust, and so with reduced melt, there will be reduced inputs of this material to the lakes and that will shift their colour."

Both Fischer and fellow science adviser Mark Olson have spent the past 17 years researching lakes in the Canadian Rockies, and in that time have spoken with numerous people. 

"I would say we're kind of connecting the dots. The land and the lake are really intimately connected. So what's happening with the glacier ice on land influences what we see in the lake," Fischer said.

In other researchers' work, they have seen an accelerated glacial melt, speeding up every summer.

"As you change the amount of meltwater inputs into these lakes, there's going to be a consequence for it," Olson said.   

The pair approached Allison to make a short film with two stipulations: they wanted it to be more than a traditional science documentary and they didn't want to be in it. 

"What the movie allowed us to do was sort of translate what we're seeing into something that people can observe," Olson said. 

"The idea for the film came about because we were hoping to do a better job of sharing our research and our findings with the general public," Fischer said.

Allison says there were several remote lakes that the crew had to hike to in different areas of the parks. To help preserve the remote lakes Losing Blue features, the crew has chosen not to disclose them.

"I literally spent like 10 days by myself in the mountains just like sitting by these lakes and filming them and getting to know each lake," Allison said.

She pointed to climate change playing more of a role than just its impact on the lakes, as filming had to be halted in 2021 due to wildfire smoke.  

"I just assumed that was always going to be there," Allison said. "I didn't even think of the fact that this blue isn't something that's going to be around forever."

The 16-minute film is a National Film Board of Canada production, available for free streaming online.