Dollard-des-Ormeaux Flooding in 2026: What West Island Homeowners Need to Know

Overview of the June 2026 Flooding Event

On Saturday, June 20, 2026, Dollard-des-Ormeaux (DDO) and adjacent West Island municipalities (including Pierrefonds-Roxboro and Pointe-Claire) were struck by a severe stationary convective storm. Over 100 to 170 mm of precipitation accumulated in approximately one to two hours, overwhelmingly exceeding the hydraulic design capacity of municipal sewer and stormwater drainage infrastructure.

Impact on Neighborhoods & Centennial Lake

• Residential Infiltration: Over 300 residential basements reported severe water infiltration, ruined drywall, flooring, and damaged foundations.
• Power Grid Interruptions: Over 20,000 residents suffered widespread electrical outages across West Island sectors.
• Centennial Park Overflow: Centennial Lake, which functions as DDO's critical stormwater retention basin, witnessed water level increases of over 2 metres in a rapid span, spilling over into adjacent road networks and pedestrian paths.

Immediate Action Plan for Homeowners

1. Timestamped Documentation: Photograph waterlines on drywall, take timestamped videos of all compromised property prior to removal or disposal, and log itemized inventories for insurance adjusters.
2. Municipal Claims & Legal Action: File formal Notice of Claim forms within statutory deadlines with the municipality. In the wake of repetitive annual flooding, proposed class-action lawsuits were filed against the City of Dollard-des-Ormeaux and the City of Montreal through Consumer Law Group alleging insufficient retention infrastructure and maintenance negligence.
3. Property Defense & Plumbing Mitigations:

• Backwater Valves: Ensure certified, normally-closed flap check valves are installed on basement drain branches and regularly cleared of sediment.
• Dual Sump Pump Systems: Maintain submersible pumps paired with secondary battery-powered backup pumps or auxiliary generators to survive storm-related power interruptions.
• Lot Grading & Downspouts: Direct eavestrough discharge extensions at least 2 metres away from foundations and inspect French drains (weeping tiles).