The review of flood zones, following disasters in recent years, means that 15,500 buildings are now found in areas at risk in the greater Montreal region, twice as many as before.
What you need to know
With the updating of the flood zone maps of the Metropolitan Community of Montreal, twice as many buildings are found in sectors likely to be flooded, i.e. 15,500 buildings, including 3,200 in high risk zones;
A new regulation presented by Quebec provides significant restrictions for the reconstruction and renovation of properties in these areas;
Elected officials from Greater Montreal are asking the government for more flexibility in its regulations, particularly for sectors protected by a dike or dam.
These 15,500 buildings represent approximately 19,000 housing units and have a property value of 9.9 billion, according to the Montreal Metropolitan Community (CMM), which produced new maps as part of the launch, last June, of a consultation public on the project to modernize provincial regulations in flood zones.
“It is certain that there is an expansion of flood zones, since the new maps take into account the floods of 2017, 2019 and 2023, years of very high water levels,” explained Nicolas Milot, director of the Ecological transition and Innovation at the CMM, during a technical briefing on Friday.
SCREENSHOT OF THE MONTREAL METROPOLITAN COMMUNITY MAPPING TOOL
The CMM noted that the number of buildings located in risk areas has doubled since these years of major floods, in sectors where it was possible to make comparisons, indicates Mr. Milot.
Among the buildings found in flood-prone areas, 3,200 are in very high risk zones, and 5,100 in high risk zones.
SCREENSHOT OF THE MEMORY OF THE METROPOLITAN COMMUNITY OF MONTREAL
“We know that areas at very high risk will eventually have to be left to the waterways,” explains Nicolas Milot. “For residents, this means that they will be able to continue to live there, but that their property will no longer be worth anything,” since it cannot be rebuilt in the event of a disaster, according to the draft Quebec regulation.
Last June, when the Minister of the Environment, the Fight against Climate Change, Wildlife and Parks, Benoit Charette, announced the update of his regulations, Quebec estimated that nearly 77,000 housing units, i.e. 2% of the population would find themselves in a flood zone according to the new maps, compared to 22,000 currently.
The update of flood zones also takes into account episodes of heavy rain linked to climate change, which risk causing more flooding in the coming years, adds Nicolas Milot.
Dikes and dams
In addition, the CMM had to include, in the flood zones, the sectors located behind a dike or other flood protection structure, at the request of Quebec.
Among the 15,500 buildings at risk, 4,650 are found in an area protected by such a structure.
The mayors of the 82 municipalities of the CMM, meeting in assembly on Monday, are asking Quebec for greater flexibility in its regulations regarding these zones.
Previously, flood zones were identified according to recurrence ratings of “0-20 years” and “20-100 years”, while the new generation of maps offers a new classification with four risk categories: low, moderate, high and very high.
For example, “very high” corresponds to a risk of more than 70% of being flooded at least once over a 25-year horizon with more than 60 centimeters of water.
Prohibition on rebuilding
According to the new regulations provided by Quebec, the construction and renovation of residences is marked according to each level of risk. For example, a homeowner in a very high risk area would not be allowed to build a new residence or rebuild a house that has been destroyed. However, he could carry out renovations, such as changing the location of the electrical entrance or creating rooms on the second floor, to make his residence more resilient to flooding.
In the “high” zone, new construction would be prohibited, unless there are exceptions, accompanied by a risk management plan.
The CMM wants Quebec to allow the transformation of buildings and the creation of management plans in low, moderate and high exposure zones, particularly those protected by a dam or dike.
“Otherwise, it doesn’t make sense, it freezes part of the territory,” notes Nicolas Milot. While cities might want to build more resilient buildings. »
Funding issues
According to him, areas protected by a dike should be identified as such, since the risk of flooding is lower there. Although the rupture of the dike protecting a district of Sainte-Marthe-sur-le-Lac in 2019 demonstrates that zero risk does not exist, Mr. Milot emphasizes that Quebec will henceforth impose regular inspections of these structures.
The new regulations also send a signal to mortgage lenders, who could decide to stop financing properties located in these areas, he adds. The government should then, according to the CMM, review its relocation and compensation program, which currently provides only $75 million for this purpose, with a maximum of $100,000 per owner.
Citizens can consult the new map online with their civic address. The flood zones could, however, change, since Quebec must approve the CMM maps.
CMM municipalities with the greatest number of buildings in flood zones
Montreal: 3145
Laval: 2569
Pointe-Calumet: 2518
Sainte-Marthe-sur-le-Lac: 1983
Vaudreuil-Dorion: 1207
Deux-Montagnes: 353
Saint-Eustache: 313
Rosemère: 291
Chateauguay: 280
Source: Metropolitan Community of Montreal