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Potential Swimming Sites in the St. Lawrence River
As part of the Monitoring the State of the St. Lawrence Program, the Ministère du Développement durable, de l'Environnement et des Parcs du Québec has been monitoring bacteriological water quality at potential swimming sites in the St. Lawrence River since 2003. In 2005, the water quality at over half of the 16 monitored sites was acceptable for swimming.
In the 1960s, public beaches along the river were closed due to public health concerns related to the poor quality of the water for swimming. Since then, clean-up measures have improved the water quality at several sites, but problems of bacterial contamination persist, especially downstream from the Montréal region.
The region of Montréal
The bacteriological water quality of Lake Saint-Louis, Lake Saint-François and the Boucherville archipelago is suitable for swimming. However, the sites downstream from Montréal, which are affected by effluent from the Montréal wastewater treatment plant, are not acceptable for swimming. Contamination by the effluent, which is treated but not disinfected, can be detected over a distance of 125 km, as far upstream as Bécancour.
The Lake Saint-Pierre region
Potential swimming sites in the Lake Saint-Pierre region are found at Tracy, Pointe-du-Lac (opposite Nicolet), Port-Saint-François (Nicolet), and Deschaillons. The quality of sites located on the Berthier and Sorel islands, however, is considered fair to poor due to effluent discharged from the Montréal wastewater treatment plant.
The Quebec City region
In the Quebec City area, the water quality ranges from fair to good. However, local sources of wastewater overflows during periods of rain can affect water quality in this section of the river.
Bacteriological contamination often occurs when precipitation is recorded one or two days before sampling. Caution must therefore be exercised when comparing bacteriological quality from one site to another. From 2003 to 2005, an improvement in bacteriological quality was observed along the shores of the St. Lawrence.
The improvement is unlikely the result of better control of wastewater overflows during rainfall events, since 68% of the sampling was carried out in dry weather in 2005, compared to only 49% in 2003.
To Know More
Hébert, S. 2006. Safety of Freshwater Swimming Sites – 2nd edition. Fact Sheet in the "State of the St. Lawrence Monitoring" series. Ministère du Développement durable, de l’Environnement et des Parcs du Québec, Direction du suivi de l’état de l’environnement.
Hébert, S. 2002. Safety of Freshwater Swimming Sites. Fact Sheet in the "State of the St. Lawrence Monitoring" series. Ministère de l’Environnement du Québec, Direction du suivi de l’état de l’environnement.
Hébert, S. and J. Belley. 2005. Le Saint-Laurent – La qualité des eaux du fleuve 1990-2003. Envirodoq ENV/2005/0095, report QE/156. Québec. Ministère de l’Environnement, Direction du suivi de l’état de l’environnement. 25 pp. + 3 app.
Hébert, S. 2004. Évaluation de la qualité bactériologique de sites potentiels de baignade dans le Saint-Laurent, été 2003. Envirodoq ENV/2004/0225, report QE/147. Québec. Ministère de l’Environnement, Direction du suivi de l’état de l’environnement. 8 pp. + 3 app.
Locke, S. and D.J. Marcogliese. 2005. A Summary Report on Swimmer’s Itch in Quebec. Scientific and Technical Report ST-234E. Environment Canada – Quebec Region, Environmental Conservation Branch, St. Lawrence Centre. 42 pages.
For more information on the swimming water quality at eligible beaches, check with the Environnement-Plage program* of the Ministère du Développement durable, de l'Environnement et des Parcs du Québec.
Ministère de la Santé et des Services sociaux du Québec – Baignade saine : Prévention des maladies infectieuses transmises par les eaux de baignade (MTEB). Questions et réponses à l’intention des baigneuses et des baigneurs (French only)
Ville de Montréal – Réseau de suivi du milieu aquatique(French only)
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