Since the start of February, the Société de conservation et d’aménagement de la rivière Châteauguay (OBV SCABRIC) has been running a door-to-door awareness campaign targeting those who live along the shores of the Chateauguay River, with a particular focus on those who live upstream of the Dunn dam in the municipality of Sainte-Martine.
The organization first began its campaign in 2020 with residents living downstream from the dam. They reinitiated the in-person campaign to emphasize the importance of protecting the shoreline, as some erosion and soil movement or slides have occurred in recent years.
Soil movement and erosion are all part of the natural degradation and transformation of shorelines; they can range from a slow and gradual creep to a sudden and violent landslide or flow.
“Sainte-Martine is at a slightly higher risk for movement than Très-Saint-Sacrement or Ormstown,” says biologist Sara Chartier, a project manager with SCABRIC. “There is a little more landfill in this area, which adds weight,” she says, noting the soil composition also contributes to the precariousness of the shoreline. “There is a lot of clay, and when it becomes engorged it can lead to larger movements of soil,” she explains, noting steeper riverbanks may also be at increased risk.
Chartier notes that while erosion is part of a natural process for the river, certain activities and changes to the landscape can accelerate erosion and lead to negative consequences. A video produced by the SCABRIC tells the story of a landslide that occurred in Sainte-Martinefollowing some heavy rains in October 2017. “It was quite scary because we were missing a big piece of our land,” says Colombe Touchette Laberge, who owns the land; she describes arriving to work in the morning to find her trees were now in the river. “All we wanted to know was whether it would stop.” Following an evaluation, she was told the slide would likely result in an abutment with “steps” leading toward the water, “which is what happened naturally,” she explains.
Two significant landslides also occurred between May 2011 and April 2012 in Ormstown, when a 50-metre section of land slid toward the river along Route 138A in Ormstown. This was followed by a more violent 150-metre landslide downriver along the Chateauguay River Road.
Prevention is key
No matter where people live along the river, certain preventive measures can be helpful in preventing the shoreline from eroding too quickly or sliding. Chartier suggests it is important to keep the shoreline clear, which means keeping all construction and storing of materials to a minimum of 15 metres from the river. All water draining from the home or property should be directed away from the river into a rain garden or some other outlet. Destabilizing activities to avoid along the river’s edge include working to build up an embankment, the installation of an above-ground swimming pool, riprapping or the spreading of loose stone or rocky material onthe shoreline, cutting into the slope to enlarge a yard, or draining water to the same area.
Chartier says that while movement can happen at any time, spring is a particularly sensitive period as ice crashing against shorelines can increase erosion, as can heavy rainfall and increased surface water from melting snow. “This can accelerate the phenomenon,” she explains, while pointing out it is always important for property owners to monitor their shorelines for new cracks, bulges, slumps, or sudden changes.
If homeowners along the Chateauguay River are worried, Chartier says it is a good idea to contact the SCABRIC, whose territory extends throughout the Haut-Saint-Laurent. The door-to-door awareness campaign in Sainte-Martine will end on March 8; however, property owners who wish to obtain more information can contact the watershed organization by phone at 450-427-0911 or by email at firstname.lastname@example.org.