What Toronto Can Learn From Mississauga to Reduce Basement Flooding

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What Toronto Can Learn From Mississauga to Reduce Basement Flooding

New program increases capacity to deal with rainfall and melting snow.

Public Works looks at public space, urban design, and city-building innovations from around the world, and considers what Toronto might learn from them.

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April showers bring May flowers, but they also bring basement flooding and a host of other issues as aging infrastructure struggles to deal with rainfall and snow melt.

Every spring, seasonal runoff tests the capacity of Mississauga’s 51,000 storm drains but Toronto’s neighbour to the west has a new tool to improve drainage. In 2016, the City of Mississauga introduced a stormwater charge, which property owners pay as part of their water bills.

Stormwater refers to water that lands on an area when it rains or snows. Plants, soil, and other natural forms of ground cover are able to absorb much of this water, reducing pressure on public infrastructure.

In contrast, paved surfaces are largely impermeable, forcing water to flow to the nearest storm drain or body of water. As it travels, the runoff picks up debris and other pollutants so that not just the quantity but also the quality of water entering the system causes problems after a storm.

Mississauga’s stormwater charge responds to three factors that increase the risk of flooding. First, in a growing city, new development replaces green spaces that naturally absorb water from paved surfaces that contribute to runoff.

Second, like many Canadian cities, Mississauga has aging infrastructure to handle rainfall. Third, climate change increases the likelihood of extreme weather, thereby putting additional strain on storm drains, pipes, and treatment facilities. Taken together, development pressure, a generation of underfunded infrastructure, and new weather patterns create a perfect storm for flooding.

However, Mississauga’s stormwater charge directs resources to these challenges. In its first year, the new charge was projected to generate $33 million in revenue. With about one third going to operations and maintenance and the remainder earmarked for infrastructure renewal, the approach has the potential to support significant improvements across the city.

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From dated drains to strange storms, the same combination of issues comes into play in Toronto. Although large-scale flood protection projects are important to unlocking parts of the waterfront, every part of the built and natural environment plays a role in adapting to the demands of rain and snow.

For this reason, Toronto Water is developing a proposed stormwater charge. City staff are currently seeking feedback from the public and an online survey is live until April 7. The aim is to deliver a report to the Executive Committee in May for presentation to Council in June.

Lou Di Gironimo, general manager of Toronto Water, explains the process saying: “We’d be asking Council for approval of the concept and the rate structure.” Even if Council supports the proposed stormwater charge, the earliest it could be implemented is March, 2019.

In Toronto, stormwater management is currently funded through fees for potable water. In fact, water (along with parking and waste) is covered by a separate budget. However, water consumption is no indicator of a property’s impact on runoff or absorption when it rains.

A prime example is parking lots, many of which have no water bill but which represent large, impermeable surfaces. The proposed charge would calculate a property’s impact on stormwater separately from water use. In this way, according to Di Gironimo, “You get closer to fairness.”

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Photo by Marcanadian via Torontoist’s Flickr Pool.

Like in Mississauga, a stormwater charge would create a dedicated source of funding to respond to seasonal challenges and extreme weather. Since Toronto Water is also responsible for supplying drinking water and treating waste water, Di Gironimo admits, “Typically if we run into pressures, stormwater management projects are the first that would be deferred.”

Toronto’s stormwater charge could go towards capital improvements to reduce basement flooding or treat runoff before it enters local rivers and creeks. Di Gironimo also notes that the proposal is “revenue neutral.” Rather than increasing costs for property owners, reductions to the water rate would compensate for the new charge.

Of course, the impacts of proposed changes all depend on the the size of a property and how much water is used. The same caveat applies when comparing cities. Mississauga demonstrates the potential of introducing stormwater charges to support infrastructure renewal but separate solutions are needed for a city as large and complex as Toronto. In order for the proposed stormwater charge go forward, politicians and property owners alike need to understand the rewards of rethinking runoff.

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