High concentrations of E. coli bacterial colonies enter St. The Lawrence River in the Montreal area and following the current to Lake Saint-Pierre and Trois-Rivières, a recent study found.
“In Montreal, in some places, there are up to one million E. coli colonies per 100 milliliters of water. The current standard for swimming is 200 colonies per 100 milliliters,” said François Guillemette.
He is an associate professor of environmental science at the Université du Québec à Trois-Rivières, specializing in ecology in St. Petersburg. Lawrence. The study was conducted aboard the school’s Lampsilis research vessel, and it found that Montreal is a major river polluter.
This is because the city only carries out an initial treatment of wastewater, removes solids, but does not disinfect the water before it is released back into the river.
Flowing feathers of E. coli can lead to beach closures, as swimming in high concentrations of the bacteria can lead to serious illness.
But it is not only E. coli that worries. The bacteria are usually an indicator that other microbial pathogens are present, Guillemette said.
These microbes, which include bacteria and viruses, can cause various infections and diseases, he explained.
“Swimming east is generally not recommended if you are downstream from the city’s sewage treatment plant in Montreal, as the concentrations are very high,” Guillemette said.
Swimming is still safe in most areas
However, this is not to say that swimming is not safe.
“Mostly along St. Lawrence, the water quality is really beautiful for bathing,” says Sarah Dorner, a water quality expert and professor at the Polytechnique Montréal.
“But we must definitely keep improving.”
Dorner has been involved in testing the water quality on the new beach in Montreal’s Verdun district, and the city was careful to close it as the bacteria were present in the area, she said.
Bacteria can be more easily found when the water level rises and near discharge points, she explained, but it moves with the current and will clear out over time. Like Guillemette, she says the concern is more about what else can be found around E. coli plumes.
“It indicates the presence of fecal material, but most often there are other pathogens that we are more concerned about,” Dorner said.
Dorner says the Montreal administration, like other municipalities along the river, is pushing for more access to St. Louis. Lawrence – takes advantage of the natural beauty of the waterway.
At the same time, these cities are aware of the risks associated with swimming in polluted water, and therefore there is an increasing effort to protect the river.
Montreal is working to improve wastewater treatment
The Jean-R.-Marcotte treatment plant, located on the eastern tip of the island of Montreal, treats all sanitary wastewater, including collected rainwater, said Audrey Gauthier, a spokeswoman for the city.
On average, the station treats every day equivalent to the indoor volume of the Montreal Olympic Stadium, she said.
The station started operations in 1984 and greatly improved the water quality in the area after decades of rapid population growth and poor wastewater management.
The station uses an advanced process to reduce the presence of phosphorus and suspended particles in water, Gauthier said, noting that it meets current environmental standards.
“However, the city wants to go even further to improve the quality of the water in the St. Lawrence River,” she said.
Montreal has been working to build an ozone disinfection unit for treated wastewater that will reduce the risk to human health while protecting wildlife and the environment, she said.
“This new plant in particular will make it possible to eliminate more than 99.99 percent of fecal coliforms as well as a very large proportion of pathogenic bacteria, viruses and other contaminants, enabling the cultivation of water sports more than a mile downstream of river,” said Gauthier.
Former Mayor Gérald Tremblay first announced that the city would disinfect its wastewater using ozone gas in 2008, but there have been some delays in recent years. The new facility, which is estimated to cost around $ 500 million, will still not be ready for a few more years.
Until then, Dorner says people can swim in the river as long as it is not too close to the sewage treatment plant.
“I did not want people to think that St. Lawrence was really polluted and they should not swim,” she said.
She said, however, “it is important to have good monitoring and let people know where the water is good for swimming.”