Drinking water production: Reports on the vulnerability of water sources

Last updated February 10, 2023

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Drinking water

The Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs (MELCCFP) requires that the city, every five years, evaluate the vulnerability of the water source for each of its drinking water treatment plants. Find the highlights of these reports here.

Drinking water is produced from treatment plants using water from the St. Lawrence River or the Rivière des Prairies. In these reports, you will find:

The main characteristics of the water withdrawal site and the description of the treatment plant.
The delineation of the inner, intermediate and outer protection zones.
The ratings for the six vulnerability indicators.

What is a protection zone?

In order to protect the areas from which drinking water treatment plants draw their water, the MELCCFP has prohibited certain activities (grazing, spreading of nitrogenous fertilizers, storage of animal dung on the ground) in proximity to water supply intakes. In its Water Withdrawal and Protection Regulation (WWPR), the MELCCFP defined its compliance perimeters: Inner, intermediate and outer protection zones. Each water treatment plant has its protection zones, established on the basis of a specific distance.

Vulnerability indicators

In order to evaluate the vulnerability of water withdrawal sites, the MELCCFP requires the assessment of six indicators:

microorganisms
turbidity
inorganic substances
organic substances
location and physical integrity of water withdrawal sites
fertilizers

Water vulnerability ratings

Montréal’s six drinking water treatment plants have a low level of vulnerability for the first four indicators.

However, a moderate to high level of vulnerability was noted for the last two indicators. The causes related to these indicators were integrated into the protection plan for the city’s drinking water sources and are subject to rigorous monitoring.