Trees Please Hamilton

Green Solutions to Air Pollution

Ecosystem services provided by trees: Stormwater filtration

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Stormwater picks up pollutants wherever it falls and transports them to the harbour. Rain falling on parking lots and streets picks up oil and chemicals, as well as garbage. Heavy rains also cause erosion, flooding, and damage to property and infrastructure in the city.

By planting more trees, erosion can be stabilized, and stormwater is intercepted. Raingardens and other green space can hold and filter rain water, preventing large amounts of flow picking up contaminants, and reducing the risk of flooding. With climate change, it will be more important than ever to incorporate green infrastructure into city design.


This Red Oak in Eastwood Park filters 1,015 gallons (3,842 litres) of stormwater each year, and the number will grow as the young tree matures.

In Hamilton, the 6,000 trees inventoried through the Trees Please project over three years – a small sample of the city’s urban forest – are filtering 6,309,660 gallons (about 23,884,661 litres) of stormwater every year. Trees Matter!

Tree Benefits

Note: not all trees are included in Open Tree Map’s calculations. Some species are not supported by the app for these calculations, and occasions where the tree could only be identified to genus are also excluded. 5,713 living trees, excludes trees noted as dead but recorded (which allows us to identify places that could use a replacement).


Author: treespleasehamilton

A project of the Hamilton Naturalists' Club and Environment Hamilton. Funding by Ontario Trillium Foundation.

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