Flood zone · Deux-Montagnes and Sainte-Marthe-sur-le-Lac · 2026
The map in force in Deux-Montagnes and Sainte-Marthe-sur-le-Lac, what the City put in place, what the 2026 framework allows, and the checklist for a house near Lac des Deux Montagnes.
Flood zone in Deux-Montagnes and Sainte-Marthe-sur-le-Lac in 2026: Both cities are protected by dikes, and that is what changes everything in the new map: a recognized protection structure lowers the exposure class. The breach of the Sainte-Marthe-sur-le-Lac dike in April 2019 flooded an entire neighbourhood; Deux-Montagnes has since built its own dike, which the modernized framework can recognize if the city shows it is safe and meets the highest standards. The modernized regulatory framework of 1 March 2026 applies: new residence prohibited in the moderate, high and very high classes and in the high-current zone, permitted under conditions in the low class; rebuilding under conditions; maintenance permitted. Before buying near Lac des Deux Montagnes: the written class for the address, an insurance quote with the flood endorsement, a lender's position (Desjardins no longer lends in high-current zones since February 2024), the certificate of location and the seller's declaration. Sources read on 15 September 2026.
Both cities are protected by dikes, and that is what changes everything in the new map: a recognized protection structure lowers the exposure class. Sainte-Marthe-sur-le-Lac adopted on 11 February a resolution to take charge of its protection structure and to carry out a performance study of the dike by 1 March 2028; the CMM states that municipalities with a structure have 24 months to have it recognized.
The breach of the Sainte-Marthe-sur-le-Lac dike in April 2019 flooded an entire neighbourhood; Deux-Montagnes has since built its own dike, which the modernized framework can recognize if the city shows it is safe and meets the highest standards.
Before buying, ask the city for the status of the protection structure in the public register of flood protection structures: it decides whether the house sits in a low exposure zone or in a higher class on the final map. The modernized framework's rules apply everywhere: new residence prohibited in the moderate to very high classes and in the high-current zone, rebuilding under conditions, maintenance permitted; the detail is in renovating or rebuilding in a flood zone.
The written class, the certificate, proof of restoration or immunisation, an insurance quote for the address and a lender's position: that is the file that defends the price, described in selling a house in a flood zone. A broker from the team who knows Deux-Montagnes and Sainte-Marthe-sur-le-Lac builds it before listing.
Both cities are protected by dikes, and that is what changes everything in the new map: a recognized protection structure lowers the exposure class. A recent certificate of location and the seller's declaration complete the answer.
A new residence is prohibited in the moderate to very high classes and in the high-current zone, permitted under conditions in the low class; rebuilding after a disaster is permitted under conditions, with a municipal permit and often immunisation.
By class and by the house's history: the flood endorsement can be offered or refused by the insurer, and Desjardins no longer lends in high-current zones since February 2024; other lenders judge case by case.
Sources: vsmsll.ca, « Cadre réglementaire sur les zones inondables »; ville.deux-montagnes.qc.ca; CMM; lus le 15 septembre 2026; Québec.ca (regulatory framework of 1 March 2026). Informational page: the City decides for your address.
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Also available in French: version française de ce guide.
Published September 7, 2026 by the Loaa & Manseur team, the number 1 team at RE/MAX Platine in 2024 and 2025, 6th RE/MAX team in Quebec, 15th in Canada and in the global top 50 according to the official RE/MAX ranking. Tell us about your project.
Équipe no 1 de RE/MAX Platine en 2024 et en 2025, 6e au Québec, 15e au Canada et dans le top 50 mondial au classement officiel RE/MAX. Réponse en moins de 24 heures, sept jours sur sept.