This popular St. John's swimming spot smells like broccoli. We asked an ecologist to find out why

Record temperatures across Newfoundland and Labrador are creating perfect swimming weather but some residents are avoiding one popular spot in St. John's due to an unpleasant odour.

For several weeks, swimmers have complained of a stench wafting from George's Pond, a beloved feature of Signal Hill.

"It reminded me of broccoli," said Kathryn Cole, a Memorial University biology student.

Cole, a swimmer herself, is studying under assistant professor Kathryn Hargan, who specializes in ecology.

CBC Radio's St. John's Morning Show asked Hargan and Cole to test the water coming from George's Pond.

St. John's residents have swum in the pond for years, but until 2022 the city actually prohibited swimming in the pond because it was used as backup drinking water. After lifting the ban, the city erected signs advising that use of the pond is at one's own risk.

WATCH I The CBC's Darrell Roberts get to the bottom of the stench:

Smell that? Georges Pond has a bit of an odour but its safe, says ecologist

2 months ago

Duration 3:01

Georges Pond, near the top of Signal Hill, is a popular swimming spot, but theres been a bit of a stink coming from it lately. The CBCs Darrell Roberts dives into the science behind that smell.

Last week, Hargan and Cole went out onto the pond in an inflatable boat to gather samples, a regular part of Hargan's work as an ecologist.

Hargan said she looks at water quality, algae and historical conditions in bodies of water.

"Things are changing," she said. "There is climate change and there's other things that are changing in the province and around the world, and so we're trying to understand what that means for the biology of ponds and what that means potentially for drinking water quality."

Something's rotten in the pond of George

Hargan examined the sample from George's Pond under a microscope in her lab atMemorial University's St. John's campus. She did find odour-causing species of algae in the sample, but said it likely isn't behind the stench at the pond.

"Most of them cause more of a fishy smell, which isn't what's been described at George's Pond," she said.

Hargan said decomposition of algae and plant matter is likely behind the smell potentially exacerbated by hot conditions.

"Often if you have decomposition you have sulfur, and that's what creates what's more often described as a cabbage smell," she said.

Hargan said a definitive answer would require regular monitoring and testing.

LISTEN | We get to the bottom of the George's Pond stink:

St John's Morning Show8:22We investigate the mystery vegetable odour at the popular George's Pond

CBC News has asked the provincial Environment and Climate Change Department if it has tested the water at George's Pond recently.

Hargan is also sending the sample to a water chemistry lab to check bacteria levels.

Harmful algae blooms can make bodies of freshwater unsuitable for swimming, but Hargan said such blooms are uncommon in Newfoundland. Based on the samples she collected last week, she said, the algae in the water doesn't make the pond unsafe.

"Like I don't recommend drinking it, but it definitely would not cause any harm to your skin if you were swimming in the pond," she said.

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