Flooding

Last updated April 20, 2022
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What areas in Montréal are prone to flooding? What times of the year are associated with the highest risk? Find out about the risk of major floods.

Montréal constantly monitors the water levels of the St. Lawrence River, the Rivière des Prairies, Lac Saint-Louis and Lac des Deux Montagnes, and also monitors weather forecasts during high-risk periods.

High-risk periods

Major floods usually occur:

  • In the spring when snow melts
  • During the winter, when ice forms and blocks a stream or river

Flood-prone areas: Zones that are at risk

Areas bordering the Lac des Deux Montagnes and the Rivière des Prairies are at higher risk of flooding. If an alert is issued, the status of the situation and measures being taken in the field will be communicated to residents quickly. 

Water levels can be viewed in real time on the Ministère de l’Environnement et de Lutte contre les Changements Climatiques Web site (in French). For residents of the St. Lawrence River and Lac Saint-Louis shorelines, the risk is low.

Available equipment and material

The city has a wide range of equipment that can be set up quickly in areas affected by flooding. Trucks, mechanical shovels and other equipment are also rented during at-risk periods.

Here is an overview of equipment and material.

  • Concrete barriers (Jersey barriers)
  • MuscleWall-type protective barriers
  • Sandbags
  • Empty bags
  • Bulk sand and pebbles
  • “Citadelle” dikes (bigwhite bags)
  • Plastic sheeting
  • Submersible pumps
  • Gas pumps
  • Generators

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