Mayor Valérie Plante Directs $85 Million to Build 30 Resilient Sponge Streets Across Montreal

MONTREAL — Mayor Valérie Plante and the Montreal Executive Committee announced on Monday the authorization of an $85 million municipal climate adaptation investment package to transform thirty residential boulevards and public squares into engineered bioretention "sponge streets" (rues éponges) and permeable rain gardens across twelve boroughs.

The project, managed by the City of Montreal Water Service and urban planning departments, replaces impermeable asphalt and concrete road gutters with sunken sidewalk bioretention cells, subterranean gravel retention reservoirs, and native perennial rain gardens engineered to capture, filter, and temporarily store over 150 million litres of stormwater during extreme cloudburst convective rainfall events.

Preventing Urban Basement Flooding and Sewer Overflows Torrential storm events have repeatedly overwhelmed Montreal's century-old combined sewer network, resulting in millions of dollars in residential basement flood damage and untreated stormwater overflows into the Saint Lawrence and Rivière des Prairies.

"Montreal is adapting to the reality of climate change by rethinking how our streets manage water," Mayor Valérie Plante said along a newly converted sponge boulevard in the Rosemont–La Petite-Patrie borough. "Instead of letting millions of litres of rainwater rush down asphalt into overloaded sewers, our sponge streets absorb water directly into the ground through beautiful green gardens and permeable tree pits. This $85 million investment protects thousands of family basements from flooding while making our neighborhoods greener, cooler, and more beautiful."

Borough Sponge Infrastructure Allocations The $85 million package includes:

• 30 Engineered Sponge Street Corridors: Constructing 45 kilometers of continuous sunken bioretention curb extensions across Plateau-Mont-Royal, Villeray, Ahuntsic, and Mercier.
• Subterranean Stormwater Infiltration Basins: Installing underground modular retention chambers beneath public parks to slowly discharge filtered water into groundwater tables.
• 5,000 Permeable Urban Tree Pits: Enlarging street tree pits with engineered porous soil matrices that prevent storm runoff while expanding urban shade canopies.

Urban water engineers, borough mayors, and insurance federations commended the municipal program, highlighting that nature-based sponge city engineering is up to 50 percent more cost-effective than constructing massive underground concrete holding tanks.