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Rivière du Nord: Better wastewater treatment is needed before you can swim between Prévost and Saint-Jérôme

Rivière du Nord


Montreal, August 11, 2023 – The Fondation Rivières reveals the results of a study on the bacteriological quality of the water of the Rivière du Nord between Saint-Jérôme and Prévost. These Cities have mandated the non-profit organization to assess the potential for swimming and water activities in order to offer their population access to quality water for the practice of these activities.

Data collected in the summer of 2022 indicates levels ofEscherichia coli (E.coli) acceptable for the practice of indirect contact water activities (canoe, kayak, paddleboard, etc.) for all sites (only one exceedance). However, the potential for swimming turned out to be non-existent since this activity requires concentrations ofE.coli lower, i.e. a maximum of 200 CFU/100 mL while that of indirect contact activities is 1,000 CFU/100 mL.

What is the origin of the problem?

The sources of contamination contributing to degrading the water quality of the Rivière du Nord are of municipal origin. In particular, high levels of fecal coliforms in the effluent of the Sainte-Adèle station (Mont-Rolland) have resulted on numerous occasions in a significant degradation of the water quality of the river in the 2 to 3 days following these observations at the station.

This uses a treatment technology different from the six others discharging their treated water upstream of the sites under study (by activated sludge and UV, rather than by aerated ponds). The Ministry of the Environment issued a sanitation certificate in the fall of 2022 requiring that a corrective program be put in place. The municipality of Sainte-Adèle has since ensured cleaning of UV lamps every month, coupled with automatic sampling at the station. Lower concentrations of coliforms have since been observed.

Problems are also observed at the Régie de Piedmont, Saint-Sauveur and Saint-Sauveur-des-Monts. Optimizing the operation of the aerated ponds at the treatment plant would ensure the quality of the water in the Rivière du Nord downstream. 

“These results are very encouraging. It will be enough to optimize operations at the Régie station. This should allow to comply at all times with discharge standards and (see erratum below) to protect the water quality of the Rivière du Nord. » – André Bélanger, general director of Fondation Rivières. 


One more step towards swimming in downtown Saint-Jérôme

This study follows a study carried out in 2021, in which the City of Saint-Jérôme also participated. The 2021 study aimed to assess water quality with a view to making swimming safe in the city center, at Place du Curé-Labelle. Three sources of contamination had been detected. Two of them have since been eliminated, but one persists upstream of the Lajeunesse Boulevard bridge. The 2022 study made it possible to update and expand the water quality portrait, as well as to detect sources of pollution upstream of the city center. 

This study was carried out thanks to funding from Ministry of Municipal Affairs and Housing as part of the Support for regional outreach component of the Regions and Rurality Fund. The study developed by the Fondation Rivières is in collaboration with the Territorial Institute and the Quebec Federation of Hunters and Fishermen (Laurentides region), to highlight the Rivière du Nord. 

The Fondation Rivières is continuing its efforts to provide access to the Rivière du Nord by monitoring water quality between Mirabel and Saint-André-d'Argenteuil in the summer of 2023. 


The Fondation Rivières collected a total of 149 surface water samples at four regular monitoring sites, twice a week, between July and September 2022. The analysis was based on the count ofEscherichia coli (E.coli). 

ERRATUM: The initial version of the press release alluded to non-compliance with the additional standard for discharge of fecal coliforms. In reality, although occasional exceedances of the discharge standard set at 2,000 CFU/100 mL were noted in 2022, the standard was respected since its application is based on a geometric average calculated over all of the summer period. Beyond compliance with the standard, it is however important to optimize the operation of the wastewater treatment plant in order to avoid these contamination peaks and to ensure that uses in the Rivière du Nord are preserved. 

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Sophie Lachance

Sophie Lachance

Communications and Mobilization Manager
Fondation Rivières
514-272-2666, ext. 307

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