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Châteauguay Watershed - Wastewater Treatment Systems Assessment

Châteauguay zone watershed – Evaluation of wastewater treatment systems

Credit: Gilles Douaire 

The issues affecting water quality in the Châteauguay area under the microscope

Fondation Rivières carried out a performance evaluation of municipal wastewater treatment systems in the Châteauguay zone watershed. The objectives: identify sanitation issues that remain between 2014 and 2016 and produce a report that serves as an information tool for municipal decision-makers, interest groups and the public.

SCABRIC évaluation assainissement Zone Châteauguay

Study area of municipal wastewater treatment works in the Châteauguay zone.


Progress report

  • Data compilation Monitoring system for municipal water sanitation works (SOMAE)
  • Interpretation of diagrams and tracking data


Diagnosis and action plan

  • Telephone interviews with many water sanitation services
  • Production of a summary table of suggested courses of action


Partners and collaborators

  • Society for the conservation and development of watersheds in the Châteauguay area (SCABRIC)
  • Hinchinbrooke
  • Huntingdon
  • Ormstown
  • St. Chrysostom
  • howick
  • Saint-Urbain-Premier
  • Sainte-Martine
  • Mercier
  • Chateauguay
  • Saint-Anicet
  • Saint-Stanislas-de-Kostka
  • Saint-Louis-de-Gonzague
  • Beauharnois
  • St. Barbara
  • Saint-Étienne-de-Beauharnois
  • Lery
  • Saint-Isidore (Montérégie)
  • Saint-Rémi
  • Saint Catherine
  • Delson
  • Candiac
  • The Meadow
  • Saint-Philippe
  • Hemmingford
  • Saint-Jacques-le-Mineur
  • Longueuil



Treatment plants
Overflow structures
Courses of action

The raw data from Monitoring of municipal wastewater treatment works (SOMAEU) 2014-2016 were obtained from three different sources, namely the Society for the Conservation and Development of Watersheds in the Châteauguay Zone (SCABRIC), Ministry of Municipal Affairs and Housing (MAMH) and the Ministry of the Environment and the Fight against Climate Change (MELCC).

Of the 33 entities identified, 27 participated in a telephone interview or sent written responses (82 % participation). The study areas were created by combining several watersheds to obtain a substantial number of features in each area. Overall, this project led to the synthesis of information and a performance diagnosis, based on three components: characteristics of the entities, performance of the treatment plants and performance of the networks and overflow structures.

Duration of the study

The evaluation of wastewater treatment systems took place from October 2018 to June 2019.



Around a third of stations have an adequate treatment system, but a sanitation network in need of improvement


Only one station has a sanitary network that meets MELCC requirements, but must improve its wastewater treatment performance


Five entities must improve the performance of their wastewater treatment plants and their sanitation network.

Investments at the watershed scale are required in order to address the most relevant interventions to maintain water quality in the Châteauguay area and the environment.

How is the water quality in the Châteauguay area?

Two years after this evaluation of wastewater treatment systems, Fondation Rivières carried out a study on the water quality of the Châteauguay River in order to assess the swimming potential. This mandate not only made it possible to see that swimming was possible in summer, but also that the willingness of municipalities to work to correct water treatment problems contributes to improving the quality and public access to a resource. precious natural.

Our mandates for evaluating wastewater treatment systems

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