Controlling Stormwater in Montreal with Sponge Parks

By Marie-Claude Allard

Overview

In 2021, the City of Montreal launched a program to promote two complementary initiatives: green street drainage infrastructure and sponge parks. The team responsible for these initiatives, led by Marie Dugué, Section Head of Planning and Major Projects, Water Services, was tasked with providing tools, advice, and financial assistance to boroughs and central services regarding green infrastructure for street drainage and sponge parks. Although these two components were developed simultaneously, they have distinct characteristics in terms of their scale and functions.

Green infrastructure on streets includes, among other things, vegetated curb extensions located at a lower level than the roadway that capture and infiltrate runoff during light rainfall. The main purpose of such interventions is to reduce sewer overflows by managing small amounts of precipitation. This also promotes greening, reduces heat islands, and improves pedestrian safety.

For their part, sponge parks temporarily capture large volumes of water during heavy storms. Water from surrounding streets is directed at the surface toward a low-impact area (the park), held there, and then returned to the sewer once capacity becomes available again. The purpose of sponge parks is to reduce the frequency of flooding for the surrounding neighbourhoods. 

Referring to the severe storms that hit Montreal in recent years, Dugué explains, “Every time it rains, water enters the street drains. Recently, we’ve had some very severe storms. We had two in 2024, we had others in 2023, and for several years now, we have been experiencing events that exceed all the statistics we usually have. And now, in the sewer system, the water can no longer get in because there is too much water falling on the street. That’s when we try to direct these rivers of water flowing along the streets toward these parks. We want to flood an area of lesser impact in order to protect or reduce the frequency of flooding in residential and commercial areas. So we often hold the water temporarily until the sewer has capacity again. Then, we return the water to the sewer system.”

Since 2022, the City of Montreal has implemented 23 sponge parks. Here is a list of the five largest sponge parks as of 2025, along with their retention capacity:

• Pierre-Bédard Park / 5,735,000 liters
• Pilon Park / 1,373,000 liters
• Park at the intersection of Joseph and Dupuis streets (name to be determined) / 1,067,000 liters
• Howard Park / 750,000 liters
• Pierre-Dansereau Park / 627,000 liters

As for green infrastructure, since 2022 the City of Montreal has reached 2,500 “cells” (meaning individual units or functional modules that make up a stormwater management system), either built or under construction, for a total area equivalent to about 6 soccer fields, or roughly 45,000 m².

Related benefits

Although these two components bring greenery to the city and reduce heat islands, one aspect of this project that should not be overlooked is the effort and motivation of the teams. As part of a project that is now proving its worth, each team involved is proud to be part of such an initiative.  

As Dugué explains, “What also helps a lot is when you have good examples. Then things start to fall into place.”

During this period, Ms. Dugué’s team not only carried out pilot projects in urban areas, but also thought strategically about how to continue the actions thereafter.

Hugo Bourgoin, media relations officer with the City of Montreal’s Public Affairs and Protocol Department added, “What’s wonderful about sponge parks is that 99% of the time, they provide co-benefits. These spaces are used by citizens. Children can go play there, families can picnic in these parks, they use them. And the 1% of the time when  rain is too intense and the sewer system can’t keep up, the park is partially flooded to accommodate that volume of water and relieve some of the pressure on the sewer system.”

A now quantifiable goal

In 2022, the city set a quantitative target: to build 8,500 m² of green infrastructure on streets between 2022 and 2025 and to provide 9,000 m³ of retention capacity in parks over the same period.

These projects would not have been possible without funding from the Ministry of the Environment. Through the green economy program, the city obtained $117 million for various elements, including $15.5 million dedicated to water services. This made it possible to assemble a team of experts to support the boroughs and central services carrying out the projects, producing tools, and conducting research.

As Dugué explains, these projects are cross-sectoral: “Of course, the project leaders are mostly in the boroughs; they are either in the boroughs or the central service, which is actually the Urban Planning and Mobility Department. The Parks and Sports Department also own these spaces and initiate the projects, commission consultants or design them internally, and supervise the work afterwards. My team is really there to support these teams in integrating water management. One of the interesting players is the Office of Ecological Transition and Resilience, which helps us find funding and increase various benefits.”

Finally, other sources of funding came from the Green Municipal Fund, the Flood Resilience and Adaptation Program (Programme de résilience et d’adaptation face aux inondations – PRAFI in French only), and the Sustainable Stormwater Management Program (Programme pour la gestion durable des eaux de pluie – PGDEP in French only), which are programs of the Ministry of Municipal Affairs, as well as the Disaster Mitigation and Adaptation Fund (DMAF), which is a federal program.

Implementation approach

To properly analyze the environment targeted by the project, the team used topographical data. This made it possible to assess street slopes, catchment areas draining towards a park, and vulnerable low-lying zones.

As Dugué explains, “It’s important to understand that we took a very opportunistic approach, which may be a little different from other municipalities.  In other words, the City carries out a great deal of rehabilitation work to maintain its assets, including its sewer and water systems under the streets.  So we are rebuilding the entire street with sewers and water mains, and we are also doing a lot of work to refurbish our parks.  So whenever work was planned, we tried to integrate water management into it as well as we could.”

The goal is to better understand the basin areas in the city in order to identify the most vulnerable areas. Subsequently, the structures built in Montreal’s database are listed for asset management purposes.

Challenges and governance

The main challenge in this project is to train and coordinate a multitude of stakeholders across 19 boroughs.  These stakeholders may include planners, landscape architects, engineers, planning and specification teams, contractors, maintenance workers, and external professionals.  The team chosen must therefore consolidate and coordinate all of these stakeholders, which can be a challenge in itself.

Tools have been put in place to strengthen the capacities of those involved in this project. Approximately 200 training sessions have been provided citywide, as well as internal and external webinars on planning and design, developed by the Regional Council for the Environment (Conseil régional de l’environnement – in French only). In terms of published tools, catalogs, design and construction checklists, and videos documenting maintenance have been used to support those involved.

Outreach and external exchanges

The sponge parks project in Montreal attracts many visitors and encourages the sharing of experiences. In fact, many municipalities in Quebec, as well as countries such as South Korea and New Zealand, are interested in this project.

“We also participate in pan-Canadian working groups to share our experiences. We were recently invited to Singapore to present our projects. This has helped raise our profile,” explains Dugué.

The comments from Montreal citizens about sponge parks are generally very positive. There is increasing use of these spaces by the population.  However, the current issue hanging over this project, an issue that could be described as a challenge, is its popularity.

“We are actually victims of our own success!  The workload is increasing significantly,” says Dugué. 

The success of sponge parks and green infrastructure on streets in the City of Montreal demonstrates an innovative approach that can inspire communities here and elsewhere. With this growing interest, it will be interesting to see where new collaborations will emerge to build a more sustainable urban future.