The St. James Creek runs through several backyards, snaking through Pointe-Claire and Beaconsfield before emptying into Lac Saint Louis.
Locals say children sometimes play nearby, and have even occasionally paddled a canoe in the small creek.
Data from the City of Montreal’s public website show that samples taken in 2013 and 2014 at the point where the creek meets Lac Saint Louis revealed levels of fecal coliform well above 1000 units per 100 millilitres — which is considered polluted.
At some points, the levels were as low as 200 units, but at other times samples were as high as 3,000 and 4,000.
The latest test from the mouth of the creek, taken on Oct. 27, revealed the level was at 4,500 units of fecal coliform per 100 millilitres.
Angela Collins says she first learned about the pollution from CBC’s Daybreak. The creek runs through her backyard.
She says the City of Beaconsfield should have warned her about the water.
“If at least they had told us. But to simply ignore the hazards and not advise your taxpayers ... I find very frustrating,” Collins told CBC’s Daybreak.
Collins says her husband has walked through the creek, and has used his bare hands to clear out plastic bags and other litter.
“We have the dog and the tennis ball will fall into the water every so often ... so we pick it up out of the water and then just throw it back to the dog.”
“It's a little frightening that we're living with this and no one tells us about it.”
Cause of pollution remains unclear
When CBC’s Daybreak first contacted the mayor of Beaconsfield about the polluted creek, he seemed as surprised as residents.
Beaconsfield city manager Patrice Boileau insists there is no cross connection from sewer pipes in Beaconsfield.
He says the source of the pollution is not from Beaconsfield, unless it's coming from animals.
Boileau says it's possible animal waste could cause levels of fecal coliform to increase, especially after a couple of days of rain.
Montreal public health: Don't drink or touch the water
According to the Montreal public health department, the creek is only a risk if residents come into physical contact with the water or if they drink it.
Norman King, the manager of urban environment and the health sector for the Montreal public health department, says contact with the water could cause skin irritation problems.
He said drinking the water directly, or touching the water and then accidentally touching your mouth could also lead to gastroenteritis.