At the beginning of the 19th century, Montréal was the scene of substantial industrial development. The St. Lawrence River then became one of the main manufacturing production centres in Canada. This rapid industrial and commercial growth was profitable for Montréal, but also contaminated the soil and watercourses.
At the end of the seventies, it became difficult to dilute the sewage discharged into the St. Lawrence River by these industrial firms, despite the impressive flow of water in the river. The deterioration in the quality of the river water put an end to a number of recreational and boating activities. A number of fish species were also seriously in danger of extinction.
In 1978, the Québec government set up an ambitious program to decontaminate the watercourses in Québec, aimed at curbing the various forms of pollution causing the deterioration in the quality of the water in the river. Today, the good quality of the water in the St. Lawrence River has been restored. Montrealers have resumed their recreational activities along the river, such as surfing, kayaking, rafting and fishing, to name a few.