Mississauga investing in stormwater infrastructure after ‘historic’ weekend of flooding

Mississauga’s mayor says the city has begun investing in stormwater infrastructure to better protect the community from weather challenges following a weekend of torrential rainfall and localized flooding.

Mississauga was among the Greater Toronto Area (GTA) cities most impacted on Saturday, Aug. 17, when the stormy weather disrupted traffic and closed some local parks and trails.

Photos and videos shared online showed roadways and parking lots submerged in water, with drivers forced to flee their vehicles. Intersections were also completely flooded in parts, while some areas near Dixie Road and Dundas Street Cooksville Creek, Streetsville, Malton, Lisgar, highway stretches of the 401, 403 and 410, and the airport were heavily impacted.

Mississauga Mayor Carolyn Parrish said that during the weekend, the city saw varying amounts of rainfall, from 6.2 millimetres to as much as 170 millimetres in some areas.

“This storm is considered a ‘100-year storm,’ but is occurring more regularly. In fact, we received almost the same amount of rain just one month ago, on July 16,” Parrish said.

“Our city has been making significant investments in stormwater infrastructure to better protect against such events. These efforts are part of our broader strategy to increase our resilience and make sure we are prepared for future weather challenges. The scale of this flooding event, and the one on July 16, has tested our systems, and we are actively assessing how we can further improve and adapt our infrastructure to meet these ever-changing demands.”

Toronto records more than 150 mm of rain

Parrish said that in 2024, the city had already invested $33.7 million in stormwater improvements, focusing on projects along Cooksville Creek and Etobicoke Creek and erosion control initiatives.

“Since 2016, we have invested more than $231.5 million in stormwater infrastructure,” added Parrish.

“Our 10-year plan includes an additional $340 million for ongoing upgrades and maintenance to enhance our resilience against future storms.”

Saturday’s downpour dumped 128.3 millimetres of rain at Toronto Pearson International Airport. That topped the 2013 record of 126 millimetres recorded at the airport, which is on tap for its rainiest summer ever. The previous record for summer rainfall stood at 396.2 millimetres, but Pearson Airport has already seen 475.7 millimetres this season.

In addition to the heavy rainfall, a tornado touched down Saturday morning in the Ayr, Ont. community, about 115 kilometres southwest of Toronto.