High Road Salt Levels May Be Endangering Juvenile Salmon in the Lower Mainland

Road Salt Could Be Threatening Juvenile Salmon in Lower Mainland Streams, UBC Research Suggests

The widespread use of road salt on Lower Mainland roads during fall and winter may be harming juvenile salmon, according to new research from the University of British Columbia (UBC).

Preliminary findings from a three-year study—conducted collaboratively by UBC, Simon Fraser University (SFU), the British Columbia Institute of Technology (BCIT), and Fisheries and Oceans Canada—examined 30 regional streams.

“Adult salmon thrive in saltwater but develop in freshwater, requiring significant physiological changes,” explained UBC zoology master’s student Carley Winter. “There’s evidence that exposure to high road salt concentrations during early development can lead to death and deformities in salmon.”

To assess the impact, researchers deployed 40 water quality monitors across the region to detect salt contamination spikes. They replicated those conditions in a lab using salmon eggs and juvenile fish.

The findings were stark. Salt pulses in streams—lasting about a day—reached concentrations 10 times higher than the acute water quality guideline for freshwater chloride, equating to approximately 30% of seawater salinity. Laboratory tests revealed these conditions significantly reduced the survival of salmon embryos.

For instance:

• Salt levels eight times above provincial guidelines caused a 70% die-off of salmon eggs.
• Salt pulses three times the guidelines resulted in 4% of surviving hatchlings developing fatal deformities.

“Our data suggests that salting roads at current levels during November and December, when salmon are spawning and embryos are developing, poses a serious risk to coho and chum salmon,” Winter said.

Although the results are preliminary and not yet peer-reviewed, the researchers have already identified actionable changes to reduce the impact.

UBC zoology master’s student Clare Kilgour emphasized using the minimum amount of salt required to maintain safety. “For instance, only two tablespoons of salt per square meter is needed,” Kilgour said. “When salting driveways, spread it out evenly instead of clumping, which uses much less salt for the same effect.”

The team also recommends cities transition to brine for road treatment, which uses half the salt while being more effective at adhering to surfaces.

Future research will explore the non-lethal effects of excessive salt on salmon and eggs, while a partner team at SFU plans to study the impact on juvenile coho salmon next fall.