Three Vital Natural Resources of Toronto

Toronto’s prosperity and livability rest on three foundational natural assets:

1. Freshwater — Lake Ontario

• Source: Lake Ontario (14th largest lake globally, 18,960 km²) forms Toronto’s southern boundary.
• Drinking Water: Supplies 4+ million residents via 4 treatment plants (R.L. Clark, F.J. Horgan, R.C. Harris, Island).
• Ecosystem: Supports cold-water fishery (salmon, trout), wetlands (Toronto Islands, Tommy Thompson Park), migratory birds.
• Economy: Port of Toronto (cargo, cruise), marinas, waterfront tourism, cooling for buildings (Enwave Deep Lake Water Cooling).
• Challenge: Pollution legacy, combined sewer overflows, invasive species (quagga mussels, round goby).

2. Green Space — The Ravine System

• Scale: 11,000+ hectares of ravines, parks, valleys — 17% of city land area, one of world’s largest urban ravine networks.
• Key Corridors: Don Valley, Humber Valley, Rouge Valley (Canada’s first national urban park), Taylor Creek, Highland Creek.
• Functions: Flood mitigation, biodiversity corridors (deer, coyote, 200+ bird species), recreation (300+ km trails), air purification, urban heat island reduction.
• Threats: Invasive species (buckthorn, garlic mustard), erosion, development pressure, climate change (extreme rainfall).

3. Mineral Deposits — Building the City

• Shale & Limestone (Georgian Bay / Queenston Formations): Quarried historically for cement, aggregate, brick (Don Valley Brick Works).
• Sand & Gravel (Oak Ridges Moraine, glacial deposits): Concrete, road base, construction fill.
• Glacial Till / Clay: Foundation engineering, landfill liners.
• Current Status: Most urban quarries closed/reclaimed (e.g., Evergreen Brick Works). Active extraction shifted to surrounding GTA (Caledon, Dufferin).

Interconnected Systems

These resources are linked: Moraine aquifers (Oak Ridges) filter rainwater → feed ravine streams → flow into Lake Ontario. Protecting the moraine (provincial Greenbelt) safeguards water quality and green space integrity.

Toronto’s natural capital isn’t just scenery—it’s infrastructure. Managing it sustainably is the city’s 21st-century challenge.