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Projects: L’Assomption River – Water quality monitoring

L'Assomption River - Water quality monitoring

A beach in L’Assomption thanks to Fondation Rivières and its partners

The Fondation Rivières carried out a study on the bacteriological quality of the water of the L'Assomption River. The objectives: evaluate the swimming potential at Léo-Jacques Park and validate the relevance of using a rapid analysis tool to monitor fecal contamination at the City's drinking water intake. The Foundation also sought to characterize the types of fecal contamination at this location: are they of animal origin, as popular belief would have it, or simply human?


Partners and collaborators

Site (s
Enzymatic measurements
Molecular analyzes
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The water quality monitoring study in the L'Assomption River was carried out using new rapid analysis technology, by enzymatic reaction, which gives a result in less than a quarter of 'hour. It was using a ColiMinder device, provided free of charge by the École Polytechnique de Montréal, that samples from the water intake were analyzed every two hours. The device transmitted its data online, which enabled real-time tracking.

The ColiMinder was also used to quickly analyze samples at the Léo-Jacques Park beach by the Ville de l'Assomption team, to ensure early closures during contamination peaks. The traditional laboratory enumeration method was also used to corroborate the ColiMinder results and the validity of preventive closures based on these rapid analyses.

Finally, the Fondation Rivières carried out sampling campaigns on the upstream rivers with the aim of determining the origins of bacteriological contamination in dry weather and in rainy weather. Was it of animal origin, either bovine or porcine, or human? The National Institute of Scientific Research (INRS) was responsible for carrying out molecular analyzes in the laboratory in order to characterize the nature of the fecal contamination captured during our campaigns.

Duration of the study

The project lasted from August to December 2020.



The water is generally adequate for swimming during the summer months.


From September onwards, there was persistent pollution and intensive municipal discharges upstream.


Water contamination byEscherichia coli (E.coli) is mainly of human and non-agricultural origin.

Safe swimming is therefore possible in summer in the L'Assomption River.

Have you visited the beach at Parc Léo-Jacques?

In addition to offering a breathtaking view of the L'Assomption River, Léo-Jacques Park has been offering access to a safe beach since 2021. It's the perfect place to cool off on hot summer days! Thanks to continuous monitoring by the ColiMinder, bathers can check the state of the beach water daily via the summer leisure map.

Do you make decisions within your municipality?

Consult the guide to opening an urban swimming site to find out how the Fondation Rivières can help you.

Plage de Verdun
Verdun beach in summer 2021

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