Combined Sewer Overflow points - Wastewater Systems Effluent Regulations

The Wastewater Systems Effluent Regulations (WSER), developed under the Fisheries Act, came into force in 2012 to manage wastewater releases by systems that collect an average daily influent volume of 100 cubic metres or more. The WSER also does not apply to any wastewater system located in the Northwest Territories, Nunavut and north of the 54th parallel in the provinces of Quebec and Newfoundland and Labrador. The WSER set national baseline effluent quality standards that are achievable through secondary wastewater treatment.

The province of Quebec provided some combined sewer overflow data for 2020, which includes information on whether a discharge occurred at a combined sewer overflow point during the year. The map below shows the number of CSO points with at least one overflow event within each wastewater system.

The map is available in both ESRI REST (to use with ARC GIS) and WMS (open source) formats. For more information about the individual reporting wastewater systems, datasets are available in either CSV or XLS formats.

More information on the wastewater sector including the regulations, agreements, contacts and resource documents is available at: https://www.canada.ca/wastewater

Data and Resources

Additional Info

Field	Value
Last Updated	April 17, 2026, 17:37 (UTC)
Created	April 17, 2026, 17:37 (UTC)
contact_email	eu-ww@ec.gc.ca
contact_person	{"fr": "Gouvernement du Canada; Environnement et Changement climatique Canada,ec.enviroinfo.ec@canada.ca", "en": "Government of Canada; Environment and Climate Change Canada,1-800-668-6767,ec.enviroinfo.ec@canada.ca"}
criticality_level	[]
data_dictionary	["environment"]
geographic_scope	[]
open_canada_collection	fgp
open_canada_date_published	2022-03-02 00:00:00
open_canada_keywords	{"fr": ["Test réglementaire", "eaux usées", "eau", "rejet", "effluent", "eaux-vannes", "SIRRE", "RESAEU", "surverses des égouts unitaires", "surveillance", "rapports", "traitement", "Loi sur les pêches", "substances nocives", "pollution de l'eau", "qualité de l'eau", "Eaux usées", "Règlements", "Évaluer la toxicité de la présence dans l'environnement des substances et des déchets dangereux; les gérer et les surveiller", "Planifier et mettre en œuvre l'infrastructure de surveillance dans le but d'évaluer la présence et les niveaux de substances préoccupantes", "National (CA)", "Direction générale de la protection de l’environnement", "Direction des secteurs industriels et des substances chimiques", "3.1.2 Gestion des effluents", "Non Classifié"], "en": ["Statutory Instrument", "wastewater", "water", "discharge", "effluent", "sewage", "ERRIS", "WSER", "combined sewer overflow", "monitoring", "reporting", "treatment", "Fisheries Act", "deleterious substances", "water pollution", "water quality", "Waste water", "Regulations", "Assess Toxicity; Manage and Monitor for Environmental Presence of Hazardous Substances and Waste", "Plan and Implement Monitoring Infrastructure to Assess Presence and Levels of Substances of Concern", "National (CA)", "Environmental Protection Branch", "Industrial Sectors and Chemicals Directorate", "3.1.2. Effluent Management", "Unclassified"]}
open_canada_subject	["nature_and_environment"]
sensitivity_level	unrestricted
title_fr	Points de débordement des égouts unitaires - Règlement sur les effluents des systèmes d’assainissement des eaux usées
update_frequency	P1Y