The Municipalité des Coteaux announces the preliminary conclusions of the recent photogrammetric analysis of the Delisle River. This project, carried out by the firm JFSA, was aimed at specifying bank recession projections.

In response to the landslides that occurred in July and October 2023 near rue Lippé, by-law number 303 - Règlement de contrôle intérimaire applicable aux abords de la rivière Delisle - was adopted to protect residents and riverside constructions from the risks of erosion and landslides.

In particular, this by-law established a maximum safety margin of 40 metres to govern interventions affecting buildings, infrastructures and works near riverbanks. However, in order to refine these margins, council members commissioned a photogrammetric analysis, which provided precise data on the evolution of the banks since 1965.

This advanced method makes it possible to analyze bank erosion and recession phenomena over an extended period, in order to adjust safety margins based on up-to-date data.

“These new analyses and initiatives demonstrate our commitment to making informed decisions based on rigorous science, while supporting the citizens directly impacted,” said Sylvain Brazeau, Mayor of Les Coteaux. “We will continue to work with all our partners to ensure a safe and sustainable future for our community.”

Safety margins revised in spring

Preliminary results indicate that bank recession rates are generally lower than originally estimated. These data will be used to set a revised maximum setback of 25 metres, variable according to the type of work, to protect sensitive areas.

These new setbacks will be incorporated into municipal bylaws in the spring of 2025, as a result of the revision of urban planning bylaws currently underway. This process will enable the adoption of adapted regulations, taking into account local realities and the conclusions of scientific studies.

The members of the municipal council also wish to set aside a financial reserve as early as 2026 to carry out the geotechnical studies required over time, so that the Municipality of Les Coteaux can monitor the evolution of the situation in parallel with the restoration work to be carried out. 

Financial support for geotechnical studies

In order to support the citizens concerned, the Municipality has created a financial reserve dedicated to financing the geotechnical studies required for properties located in identified risk zones.

In effect since January 1, the financial assistance covers up to 50% of costs, to a maximum of $5,000. The program will be evaluated and adjusted annually to meet community needs.