"In the rush to put out wildfires, hundreds of millions of litres of fire retardant are dropped on forests across North America. New research shows the effects they can have on water and ecosystems — especially when accidents happen" 

"In 2020, when a backcountry campfire in Alberta’s Rocky Mountains was not properly put out during a high-risk wildfire season, aircraft rushed to the scene to prevent a bigger blaze. Soon, a creek ran the colour of rust, dyed by fire retardant that was accidentally dropped directly into it. It created an otherworldly scene, and a rare opportunity for a group of scientists.

Long-term retardants, like those dropped on North Racehorse Creek near the B.C. border in southern Alberta, are key tools for fighting wildfires: they dampen the intensity of the flames and slow it down, giving fire fighters a chance to get on top of the blaze. Retardants are often dropped by helicopter or airplane on forests or on infrastructure when a fire is raging nearby, though there are restrictions on where it can be dumped, including a prohibition on spraying it over waterways.

But accidents happen.

The North Racehorse Creek incident was reported by an Alberta Forestry and Parks employee to researchers with the Southern Rockies Watershed Project at the University of Alberta. They were able to get to the site two weeks after the incident to measure the impacts on the aquatic ecosystem — a unique opportunity as most studies on the effects of fire retardants on water occur in labs."

Drew Anderson reports for The Narwhal September 2, 2025. [2]