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STORMWATER
Climate change from a Calgary perspective
Due to Calgary’s “physiographic divide” between the Rockies
and the Prairies, Frank Frigo, the city’s Environmental
Management manager, observes “we can swing from very dry
conditions to very wet and from very cold to very hot. And
all these things make stormwater management… particularly
green stormwater interventions more complex.”
In addressing those complexities, Frigo says “we’ve been
trying to integrate a lot more in the way of rain gardens,
green roofs, soil cells and tree wells [as part of ] systems that
sequester more of that runoff, which provide a number of
secondary benefits… like [larger] tree canopies that help
with the urban heat island effect…
sequestering carbon… and improved
water quality.” The latter both
“If there is a common thread that weaves through these catastrophic
by reducing runoff and trapping
events,itisthefactthatclimatechangehasunfortunatelybecomeour
pollutants.
He adds that “it is largely through
newnormal,andwithittheneedtoconstantlybeonguardforextreme
[such] green storm water intervenweather conditions in our cities.”
tions we’re able to manage a more re-
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WATER C AN ADA • JULY/AUGUS T 2025
Mark Wessel
Coming to terms with the cost of climate change
If there is a common thread that weaves through these catastrophic events, it is the fact that climate change has unfortunately become our new normal, and with it the need to constantly be
on guard for extreme weather conditions in our cities.
A reality made even more daunting by two other top of mind
numbers our urban leaders can’t ignore: that 30 per cent of this
country’s water infrastructure (such as watermains and sewers)
are in fair, poor or very poor condition with projections that it
would cost over $300 billion to replace existing infrastructure.
While there is no silver lining to such monumental funding
challenges, there may very well be a “green lining” based on how
some of our cities are creatively coping.
While Toronto continues to allocate billions toward such grey
infrastructure initiatives as watermain replacements in parts of the
city, it’s also thinking more about hybrid solutions whereby green
initiatives complement the grey, observes Kristina Hausmanis,
Senior Project Manager of Toronto’s Green Streets Program.
In a city where there is a high percentage of hard surfaces
within the downtown core that exacerbates flooding, “green
infrastructure can be quite beneficial in
reducing downstream flows (by managing water
where it falls),” observes Hausmanis.
Which is why she says, “we’re looking at
how we can redesign our public spaces to hold
water in these extreme events safely. And that
has to be done in parallel with depaving and the
creation of permeable surfaces.”
One such initiative is Greening Surface Parking Lots that includes the planting of trees and
other vegetation tied to the overlapping goals
of: reducing stormwater runoff, beautifying
public space and reducing the heat island effect.
Yet another is the city’s highly successful EcoRoof Incentive Program, which since 2009 has
led to the creation of 1.1 million square metres
of eco/green roof space that diverts 16.4 million
litres of stormwater annually.
Now, thanks to major projects such as the
370-acre Downsview Airport lands redevelopment, which by 2051 will be home to 15
new neighbourhoods and 115,000 residents,
Toronto is also “thinking big” when it comes to
green infrastructure.
“It’s one of the first development sites with an integrated
approach to stormwater management,” says Hausmanis. So in
addition to the city’s longstanding micro perspective on how
each property manages stormwater, with projects such as this
one there’s the macro view of “how do we use the parks, the
roads, the green roofs as part of an integrated system,” she says.
