Is it safe to swim at Canadian beaches? TMU study reveals new finding
Is it safe to swim at beaches in Canada?
For most people, most of the time, the answer is yes.
A new TMU study tracked water quality at beaches across Canada and found they're generally clean and safe. But researchers also uncovered something unexpected: when contamination does spike, seagulls are usually the reason – not human sewage.
“Our study found that publicly monitored beaches across the country are generally clean and safe for swimming,” said professor Ian Young, who led the research (external link) between 2023-25 at beaches in Ontario, Vancouver, Manitoba and Halifax.
What’s actually getting people sick
Across all sites, researchers found that overall rates of reported gastrointestinal illness, including symptoms such as vomiting and diarrhea, were low after beach visits. Only about 2.6 per cent of participants reported symptoms.
But that risk went up for swimmers who swallowed water during periods when E. coli levels were elevated.
E. coli is a marker of fecal contamination, and high levels trigger public beach advisories. The study confirmed those warnings work: when advisory thresholds were exceeded, illness risk increased.
TMU research shows water quality at beaches across Canada is generally safe. (Brianne Farquhar/Unsplash)
So where is the E. coli coming from?
Many people assume sewage or stormwater flow, especially after heavy rain. But Young’s team used DNA “source tracking” technology to trace contamination back to its origin, and human waste wasn’t the main culprit.
Seagulls were.
A direct link between seagulls and illness risk
When E. coli levels spiked at beaches in the study, researchers found the contamination was most often tied to seagull activity.
“This is one of the first studies to show a direct link between levels of seagull contamination and an increased risk of getting sick,” said Young.
This was a notable shift from previous beach research, which has typically pointed to human sewage as the main source of contamination and human health risks.
What to do before you head to the beach
The study’s practical advice is simple. Check local beach water quality reports before you go. If an advisory is in place due to high E. coli levels, it doesn't necessarily mean you have to stay home, but it does mean being careful.
“If there’s a warning due to high E. coli levels, consider activities that lower the chance of accidentally swallowing water — that’s really the riskiest thing,” said Young.
The study is funded by the Canadian Institutes of Health Research (CIHR). It is currently available as a pre-print (external link) .
