Residents whose homes are near waterways have been anxiously awaiting access to these maps, which are now publicly available on the MMC’s website. The maps were drawn up this summer according to guidelines set out in the province’s proposed flood-management regulations, Bill 67, unveiled in June. They are considered preliminary until that bill is adopted by the National Assembly in the spring, but the MMC has decided to make them public during the period of public consultation.
In a statement issued Monday, the MMC council called the Quebec government’s proposed flood management regulations “a good start,” but said that if the bill is not amended, it will prevent development and adaptation for flood resilience in a large portion of Greater Montreal, especially in areas situated behind current or future flood prevention structures, such as dikes.
“A new regulatory framework is essential, but it must be modified in order to give us more flexibility in its application and to ensure consistency with the reality on the ground,” said Denis Martin, mayor of Deux-Montagnes. “It must make it possible to maintain the dynamism of sectors at risk with adapted, more resilient developments, while limiting the impacts on the population.”
Flood Risk Levels and Implications
The new maps take into account flooding events in recent years, notably 2017, 2019 and 2023, uncertainty linked to climate change and the possibility that such water management systems as dams and reservoirs can fail. The result is an enlargement of flood zones in Greater Montreal.
In the past, Quebec had only two categories of flood zones: “O to 20-year,” which meant flooding was expected to occur at least once every 20 years, or 20-100 years, which meant flooding was expected to occur between once every 20 years and once every 100 years.
The draft regulation describes four levels of flood risk. The colour-coded risk levels describe both the probability of flooding and the expected level of severity (depth of water).
- Very High Risk: A greater than five-per-cent chance of being flooded in a given year, to a depth of more than 30 centimetres.
- High Risk: A greater than five-per-cent chance of being flooded to a depth of up to 30 cm, or greater than one-per-cent chance of being flooded to a depth of more than 30 cm, or greater than 0.3-per-cent chance of being flooded to a depth of over 60 cm.
- Moderate Risk: A greater than a one-per-cent chance of being flooded to a depth of up to 30 cm, or greater than a 0.3-per-cent chance of being flooded to a depth of between 30 and 60 cm.
- Low Risk: A greater than 0.3-per-cent chance of being flooded to a depth of up to 30 cm.
According to these categories, in the Greater Montreal region there are 15,508 residential buildings in flood zones, including: 3,204 in very high risk zones; 5,096 in high risk zones; 3,807 in moderate risk zones and 3,401 in low risk zones.
This represents 19,780 households, since some of the buildings are condo towers and there is at least one long-term care facility, Milot said. These buildings represent about $9.9 billion in property values, according to the municipal land evaluation roles.
Impacts on Development and Insurance
The new regulations will see more severe rules about whether and how municipalities can authorize development in flood zones and will tighten rules around the maintenance of flood protection structures, such as dikes. The regulations spell out what kind of development cities can allow and what kind of renovations homeowners can make to their properties in flood zones, which are going to be divided into four levels of severity: low, moderate, high and very high.
While the new regulations do not force the relocation of homeowners in any of the categories, each risk level is associated with different levels of constraints on building and renovating.
For example, homeowners in a very high risk areas face severe limitations on renovations and additions to their properties, because improvements raise property values, which means more costs to public compensation programs when floods cause damage. Property owners in very high, high and moderate risk zones are not permitted to demolish and rebuild their homes. In low risk zones, homeowners can demolish and rebuild, while following rules to improve flood resilience.
The MMC’s Concerns
In a technical briefing to reporters last week, Nicolas Milot, the MMC’s director of Ecological Transition and Innovation, presented the MMC’s position and explained why these maps are of great concern to those living in or near flood zones.
“Some people who were not in flood zones before are in flood zones now,” he said. “Some people who were already in flood zones are now in more severe zones with this flood mapping. So (building) restrictions will rise for each particular situation and in some cases we have to consider that the fact of being identified in a really high-risk zone means … that banks, insurers will probably re-evaluate the pertinence of continuing to insure or issue mortgages for these houses. We don’t know yet how they will react.”
Milot said it’s important the province recognize that the region is facing a severe housing crisis and can’t simply relocate homes or stop all development in these zones.
“We don’t want to build in agricultural or natural areas, so to think we can just move these houses out of flood zones and put them elsewhere … there are major constraints.”
The MMC is demanding that homeowners in all but the very high risk zones be allowed to demolish and rebuild as long as the new buildings would be resilient to flood damage.
The bill allows municipalities to propose management plans that allow for some flexibility in the rules for development, in all but “very high risk” flood zones, following a risk assessment by the province. But the bill doesn’t allow such plans to be proposed in “any flood zone that is downstream from a flood protection structure, a dam or a set of dams that influence the water flow regime of the sector”.
That would effectively rule out any such management plans in the Greater Montreal region, since the region is surrounded by waterways – the St. Lawrence River, Lac des Deux Montagnes, the Mille Îles River and the Rivière des Prairies – that are all downstream from a dam or a set of dams that influence the water flow. Much of the region is also behind current or planned flood protection structures.
The MMC also wants regions that are protected by flood protection structures — such as dikes, pumping systems or derivation canals — to be identified with a distinct colour designation (pink) to show they are protected. Another colour designation (purple) could be used to designate the “zone of precaution” (purple) immediately behind a structure that would be at high risk if the structure fails.
This would reflect the reality that while these areas are in flood zones, they are protected. New, stricter rules for maintenance of these structures by municipalities are part of the new regulations and should make catastrophes like the rupture of the dike that caused flooding in Ste-Marthe-sur-le-Lac in 2019 exceedingly rare.
There are 4,651 residential buildings located behind flood protection structures in the Montreal region, including 1,072 at very high risk; 2,334 at high risk; 943 at moderate risk and 302 at low risk. If the province were to adopt the MMC’s recommendation about recognizing the impact of flood protection structures, 4,185 buildings would face less severe building restrictions than if these structures are ignored.
The MMC is not challenging the province on its methodology for designating where the flood zones are, as this is a scientific process that has been done according to recognized criteria.
“The problem is that with the maps come the norms and rules that will affect how a citizen can modify his house, whether he can demolish to rebuild it,” Milet said. He said the concern is that with such strict rules in flood zones, these areas will eventually be abandoned, which may not make sense considering the public investments already made in these areas.
These zones are “already urbanized, roads are there, aquaducts are already there, sewage systems are already there. Do we really need and want to leave these infrastructures to go somewhere else or can we adapt these places (to reduce the risk) and to continue to live there but with more resilience and with (homes) that are less vulnerable to flooding?”
The MMC is also recommending improvements to the government’s compensation and relocalization programs for those in very high or high flood risk zones.
Public consultations by the Quebec environment department on the proposed flood management regulations ended on Sept. 17, but written submissions will be accepted until Oct. 17.
Impact on Development and Insurance
The new maps are not final, and the MMC is urging the government to engage in more robust consultations with the public before implementing the new regulations.
The MMC has a number of concerns about the new regulations, including the potential impact on development and insurance in the region.
The organization believes that the new regulations, if implemented as they are, could lead to a decline in property values and make it more difficult for homeowners to obtain insurance.
In addition, the MMC believes that the new regulations could make it more difficult to develop new homes in flood-prone areas.
The organization is calling on the government to revise the new regulations to take these concerns into account.
The MMC is also urging the government to invest in infrastructure improvements that will help to reduce the risk of flooding in the region.
The MMC believes that these steps are necessary to ensure that the region is prepared for the challenges posed by climate change. The organization is committed to working with the government to develop solutions that will protect the region from the impacts of flooding.
