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Châteauguay and Saint-Louis rivers: municipalities continue to pollute happily

Rivière Châteauguay


Montreal, April 18, 2016 - A performance analysis of the 17 wastewater treatment systems in the watersheds of the Châteauguay and Saint-Louis rivers for the period 2008-2015 shows several sources of pollution and cases of non-compliance with government requirements.

The report lists some 785 wastewater overflows, including overflows during dry weather in the town of Beauharnois for several years without any corrective action. This is an illegal situation according to the regulations and for which the Ministry of Sustainable Development, Environment and the Fight against Climate Change (MDDELCC) should have imposed fines since 2014.

In addition, the Beauharnois wastewater treatment plant does not meet treatment requirements with recurring exceedances of the 25 mg/l limit for suspended solids. In addition, this same station does not eliminate phosphorus from the water (unlike other municipalities bordering Lake Saint-Louis) and does not disinfect its water.

The Fondation Rivières sent its detailed report of information to the municipalities concerned as well as to local organizations and deputies.

Sewage spills

The palm of gold for pollution goes hands down to the town of Beauharnois with more than 50 % (404 out of 785) spills in 2015, 10 non-compliance with MDDELCC requirements and 22 wastewater overflows in dry weather . This last problem is particularly worrying because already in 2014 there were 48 overflows in dry weather. This problem has appeared every year since 2012, so it is a problem that has been known for a long time. This is an unusual loss of control in wastewater management and is all the more serious as the overflows occur in particular at the Sauvé, Saint-Louis and Julien stations, the most important in the City. It is the only municipality whose wastewater ends up in the river even though it is not raining.

Under article 8 of Regulation respecting municipal wastewater treatment works (ROMAEU), the overflow of wastewater in dry weather into the environment of a municipal sanitation facility is prohibited. Articles 23 and 28 respectively provide for an administrative monetary penalty of 10,000 $ or a criminal penalty of 30,000 $ to 6,000,000 $ for the operator of a sanitation work whose work suffers an overflow in dry weather or who does not respect the measures he has planned to mitigate or eliminate the effects of an overflow. Municipalities are required to notify the MDDELCC of such overflows or equipment failure according to article 15.

The city of Châteauguay occupies second place in the list with 258 overflows in 2015 and two cases of non-compliance with MDDELCC requirements. This is a slight improvement compared to 2014 (296 overflows) but a deterioration compared to 2013 (189 overflows). We note that the Rodrigue-Caron pumping station which receives 53 % of City water frequently overflows, approximately 25 times per year, while the Reid pumping station, which receives all City water, must be monitored, with notices of non-compliance having been issued in 2013 and 2014.


The wastewater treatment plants have excellent performance overall except in Beauharnois where the concentration of suspended solids exceeds the permitted limits of 25 mg/l reaching 57.5 mg/l for the first three months of 2015. The averages do not have not been respected for years. Phosphorus is not removed from the water and there is no disinfection system. The Saint-Isidore and Saint-Michel (Merles station) wastewater treatment plants are also deficient. The Saint-Isidore station has experienced recurring problems since 2012. The phosphorus removal objectives have never been met there since 2012 and the effluent exceeded the standard of 25 mg/l in BOD5C in 2015 with an average concentration of 36 mg/l. l, which does not comply with the regulations.
Article 6 of the ROMAEU requires that the effluent from any wastewater treatment plant meets a standard for biochemical oxygen demand after 5 days, carbonaceous part, less than 25 mg/l. Article 23 provides for an administrative monetary penalty of 10,000 $ or a criminal penalty of 30,000 $ to 6,000,000 $ for the operator of a municipal work who does not comply with the standard provided for in article 6.
Data from the Merles station in the municipality of Saint-Michel, incomplete in 2015, show non-compliance with phosphorus removal and disinfection requirements, with too many discharges of fecal coliforms, since 2010.

No data

We note that data is missing for several municipalities, which does not comply with regulations, and, therefore, the following performances could not be evaluated:
• Overflows: Saint-Rémi 2015 and 2014, Sainte-Martine 2015;
• Treatment: Saint-Rémi – 2015 and 2014, Sainte-Martine – 2014, Sainte-Clotilde-deChâteauguay – 2015 and 2014, Howick – 2015 and 2014.

Article 12 of the ROMAEU stipulates that the operator of a municipal work must transmit electronically no later than 42 days following the end of each month a report including in particular flow measurements, water sampling results and overflow readings. Article 20 provides for an administrative monetary penalty of 1,000 $ and article 24 a criminal penalty of 3,000 $ to 600,000 $ to an operator of a municipal work who refuses or neglects to transmit any information or who does not comply these deadlines.

Water treatment in rainy weather

Sewer networks and wastewater treatment plants must operate at full capacity during heavy rains. However, it is sometimes impossible to convey all the water to the treatment system. Spills to rivers are then necessary and these must be minimized when significant environmental impacts are anticipated. In addition to being foul-smelling and a serious threat to health, wastewater affects fish habitat, prevents swimming, harms water activities and fishing, and modifies ecosystems.

Annual reports

The ROMAEU requires that municipalities submit a report on April 1 of each year presenting all the information concerning the operation of the works for the previous year.

Article 20 of the regulation provides for an administrative or financial penalty of 1,000 $ for operators who fail to submit such a report on time, or a criminal penalty of 3,000 $ to 600,000 $ for the operator of a work municipal wastewater treatment plant which fails to transmit a report in accordance with sections 12 and 13 or to respect the deadlines or conditions set for their production;

All municipalities in Quebec should therefore have produced their annual sanitation performance report for the year 2015.

The data used for this assessment of Châteauguay rivers and Saint-Louis come from the monitoring system for municipal water sanitation works (SOMAE) of the Ministry of Municipal Affairs and Land Occupancy.

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For informations :

Alain Saladzius
514 924-2013

View full data

Photo: Christophe Gravel


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