Wooden studs are exposed where finished walls once stood and construction tools are scattered across the concrete floor as Arlene Thompson-Maclaren works to rebuild her basement.
For nearly 40 years, the homeowner in Dollard-des-Ormeaux, a suburb in Montreal’s West Island, never had to worry about flooding.
Today, she’s rebuilding the space for the third time in as many years.
“It’s three years in a row. August of 2024. July of 2025 and June of 2026,” she said.
Each time, the cleanup has meant tearing out insulation, drywall and flooring — “completely rip it all out and start again,” she said with a bitter smile.
Thompson-Maclaren is one of dozens of residents in Dollard-des-Ormeaux whose homes have flooded during heavy summer rain over the past three years.
Until recently, many say they never experienced flooding and are now asking the same question: What changed?
Why are Montreal’s West Island residents facing repeated flooding?
One part of the explanation, experts say, is climate change.
“We do see events now in the Montreal area and around the world that are more intense than they used to be,” said Alexis Berg, a climate science professor at the Université de Montréal.
“That’s a direct consequence of a warmer atmosphere.”
Jean-Luc Martel, a professor of construction engineering at École de technologie supérieure who studies urban flooding, says a warmer atmosphere holds more moisture, leading to heavier downpours.
“With respect to climate change, these are now more frequent events,” he said. “We should be ready to see these events more and more.”
But he says heavier rainfall is only one piece of the puzzle.
Martel says many municipal drainage systems were never expected to handle the kind of rainfall cities are now experiencing.
“The infrastructures were not designed and will never be designed to deal with those extreme rainfall events,” he said.
Susan Gaskin, a professor of civil engineering at McGill University, agrees. She also says residents who say nearby development has changed the way water moves through their neighbourhoods are not wrong.
“They are correct. The more somewhere is built up, the more impermeable surface you have,” she said.
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More pavement and rooftops mean less water can soak into the ground, sending larger volumes of runoff toward storm sewers.
However, Gaskin says newer developments are generally designed with systems that temporarily retain some of that runoff before it reaches municipal infrastructure.
The bigger challenge, she says, is adapting older neighbourhoods that were built decades ago for a different climate.
Experts say adapting cities will require a combination of approaches.
Some involve upgrading infrastructure. Others focus on changing how neighbourhoods handle rainwater before it reaches storm sewers.
“It’s not one solution,” Martel said. “Every single area will have a different solution that will be helping them more than another area in particular. Depending on the impact that you have, you need to find the right solution.”
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He says homeowners can also reduce future damage by rebuilding flood-prone basements with more resilient materials and limiting expensive finishes in spaces that are likely to flood again.
One approach gaining traction is bringing more nature into urban environments.
Chaïma Ben, executive director of the Centre d’écologie urbaine, says cities have traditionally been designed to move rainwater away as quickly as possible.
“We say bring nature back,” she said. “To remove the asphalt, to depave and plant, add more greenery, add areas that can retain the water.”
Trees, gardens and other green spaces help absorb rainwater while slowing the amount of runoff entering storm sewers during heavy rainfall.
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Ben says these nature-based solutions can complement larger infrastructure projects, which often take years and cost millions of dollars to complete.
She also encourages homeowners to prepare their own properties by maintaining backwater valves and gutters, installing sump pumps where appropriate and replacing paved surfaces with greener alternatives whenever possible.
Back in her basement, Thompson-Maclaren continues the repairs herself.
After three consecutive floods, she says she isn’t looking for someone to blame; she wants to know what comes next.
“We want to know when and how and what so we can set certain expectations,” she said.
