Water levels in the St. Lawrence River, Rivière des Prairies, Lac Saint-Louis and Lac des Deux Montagnes and weather forecasts are monitored when ice blocks a waterway in the winter and when snow melts in the spring — the two riskiest periods of the year 

If an alert is triggered, the status of the situation and the measures taken on the ground are quickly communicated to residents in affected areas: Ahuntsic-Cartierville, L’Île-Bizard-Sainte-Geneviève, Montréal-Nord, Pierrefonds-Roxboro, Pointe-Claire, Rivière-des-Prairies-Pointe-aux-Trembles, Sainte-Anne-de-Bellevue and Senneville. 

Register for the city’s Notice and Alerts service to receive the latest updates concerning your borough by e-mail or text message.

For updates on rising water levels, go to the provincial government’s Web page Vigilance – Surveillance de la crue des eaux (in French).

• Ahuntsic-Cartierville: Spring Flooding (In French only)
• L'Île-Bizard–Sainte-Geneviève: Spring Flooding
• Pierrefonds-Roxboro: Spring Flooding
• Rivière-des-Prairies–Pointe-aux-Trembles: Spring Flooding (In French only)

Heavy rain

Climate change is leading to increasingly intense rainfall episodes. Unusually large quantities of water can overload the city’s sewer system, causing overflows onto the street or property. Also, neighbourhoods where water accumulates more easily are more vulnerable. These are are known as flood-prone areas (see the vulnerability map (in French) )

Water main break, sewer backup or water infiltration 

A broken water main, a leak in a water main, and damaged or improperly installed equipment in your home or neighbourhood can also cause sewer backups or water infiltration.

Several measures can make your property more resistant to flooding. Waterproof garage doors, backwater and check valves, flat roof draining systems and gutter orientation are just a few examples. There are several subsidies available for such measures and renovations.

• Protecting your building from heavy rains
• Sewer backups: How to avoid them
• Apply to have a sewer connection repaired

Has a large amount of water overflowed from a manhole or has its cover has been moved? Let us know. In the event of a sewer backup, if you believe that a broken water main under the street is the cause, please contact us so our teams can investigate. 

If there is a risk of water infiltration in your home or if you need to evacuate quickly, the city will provide assistance. If your home has been flooded, you will find clear instructions for cleaning each room and making sure that your environment is now safe.

• Report a sewer drain issue
• Apply to have a sewer connection repaired
• River flooding: How to protect your home
• Flooding: Instructions for evacuation
• What to do after a flood