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Adopte a river - L'Assomption River

River The Assumption

Photo credit : Axel Drainville – Flickr

Adopt the L’Assomption River to:

Your contribution allows us to continue to protect Quebec's rivers

The Assomption River takes its time: its winding detours and its slow flow invite you to do the same. Half rural, half urban, it crosses both the Lanaudière forest and the urban centers of Joliette, L'Assomption and Repentigny. Although the impact of these cities has long affected the quality of its water, its health is getting better and better, as is its access to water.

Do you know the L’Assomption River?

Name Abenaki

Loigan Sibo (“river that shows the way”)

Algonquin name

Outaragasipi (“winding river”)




Assomption Lake (Mont-Tremblant National Park)



Total elevation


Average flow

24 m3/s

Lanaudière playground

The L'Assomption may have a rather low average flow, but some sections lend themselves well to white water sports! Canoe, kayak and even canoe-camping enthusiasts are catered for, especially in the Saint-Côme area. The Chutes-Monte-à-Peine-et-des-Dalles regional park also offers a pleasant experience along the L’Assomption River. In winter, you can even slide on the ice that covers it! In L'Assomption, an ice rink extends for nearly 10 km on this waterway.

“The As-swamp-tion” is no more

Formerly called “The As-swamp-tion” because of its marshy appearance and strong smell, this nickname no longer quite suits it! If the water quality of the L'Assomption River has long been affected by urbanization and agriculture, like the Châteauguay River, it is doing much better today. This is notably thanks to the investment of municipalities in wastewater treatment systems.

Photo credit : Eunice Gibb

What are the environmental issues?

Water quality

The agricultural industry constitutes the main pressure facing L'Assomption. There are contaminants from pesticides and fertilizers (nitrogen, nitrates, nitrites, phosphorus, etc.). According to Report on the state of water resources and aquatic ecosystems in Quebec (2020), the L'Assomption River frequently exceeds the admissible thresholds in terms of suspended matter and turbidity, in addition to the criteria necessary for swimming. Although the water quality is not very good in general, there are still some places that are protected from this contamination, such as Léo-Jacques Park.

Fondation Rivières and the City of L'Assomption collaborated on a pilot project in 2020 to detect fecal contamination of water in almost real time. This project also aimed to identify the different sources of contamination throughout the river and tributary basins for drinking water consumption. Our results demonstrate that fecal contamination is more linked to sanitation works rather than agricultural activities (bovine or porcine origin).

The Fondation Rivières made a evaluation of wastewater treatment works on the scale of the L'Assomption River watershed and the Saint-Laurent area. The objective: to identify sanitation issues between 2014 and 2016 and to equip municipal decision-makers, interest groups and the public with a detailed report.

Since 2020, the Fondation Rivières has disclosed the list of municipalities that stand out in terms of the intensity of their wastewater discharges into waterways, including the L'Assomption River. This exercise makes it possible to distinguish municipalities which have improved their situation in previous years from those where the situation has deteriorated. THE prize list serves as a lever to encourage elected officials to make the necessary corrections to improve the health of the rivers into which wastewater is discharged.

The previous year, it was in Saint-Paul-de-l'île-aux-Noix and Mont-Saint-Hilaire that these mobilization events took place. Swimming not only allows us to adapt to heatwaves that are becoming more and more frequent with climate change: by opening a swimming site, a municipality undertakes to ensure the quality of the water there.

Is the L’Assomption River swimmable?

Our study on water quality in L'Assomption shows that swimming is possible in summer! Since then, we can relax and swim at the beach Léo-Jacques Park, open at all times when the temperature permits. However, the water quality does not allow swimming downstream, near Repentigny.

Is the L’Assomption River navigable?

Yes! Discover the canoe routes of the L’Assomption River by accessing the Canot Kayak Québec and Eau Vive Québec map

Parcours canotables - Eau vive Québec et Canot Kayak Québec

Providing access to water for everyone

Not so long ago, there was no access to the L'Assomption River allowing swimming in an urban area... until the Fondation Rivières got involved.

The City of Repentigny has mandated Fondation Rivières to assess the swimming potential on its territory, particularly at Entramis Park on the L’Assomption River. The potential turned out to be non-existent, but the City's implementation of the Foundation's recommendations should make it possible to improve the quality of the water so that people can one day swim in it.

Two years earlier, the Foundation confirmed the swimming potential at Léo-Jacques Park in L’Assomption!

Bank erosion

In agricultural areas, it is crucial that there is control of bank erosion to prevent contaminants from entering the river. In fact, through runoff, contaminants are captured in the rain and travel to the L'Assomption River. The banks act as barriers and block this runoff.

Photo credit : Gilles Croteau

Invasive species

The L'Assomption River is a refuge for some invasive species such as the curly pondweed and the water chestnut. These species tend to spread exponentially and destroy those naturally present in the river – smallmouth bass, brown bullhead, walleye, etc. We even find certain species in a precarious situation, such as the pink-capped shiner.

Help us by adopting the L’Assomption River

The Fondation Rivières is mobilizing on this river to:

Donate and join an important mobilization movement!

Charity receipt

Fondation Rivières issues tax-deductible donation receipts, regardless of the amount. A receipt will be sent to you by email at the beginning of the year following the year of your adoption.

Make a difference for the environment

Become a member of the Foundation by donating. Your contribution allows our team to continue to mobilize to protect Quebec's rivers and waterways for future generations. 

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