Ontario's Flooding Problem

Climate Change

It’s now accepted wisdom that frequent floods are no coincidence. With climate change, most of Canada will experience higher than average rainfall. Add the greater snowmelt run-off caused by rising temperatures, and more severe storms, and the risks of urban flooding across Canada have grown. These stark realities mean that governments, in particular the province of Ontario, need to urgently increase action on flood prevention, climate change mitigation, and adaptation — with natural infrastructure solutions as an increasingly favourable way to reduce flooding’s harm.

“Flooding is the evolving normal because climate change is here to stay.”
Head of Intact Centre on Climate Adaptation

Flooding Timeline

Summer 2013

The most dramatic urban flooding Toronto has seen since 1954 occurs on July 8, 2013. Over 120 millimetres of rain falls on the GTA during the afternoon rush hour. This causes $1 billion in insurable losses and strands thousands of commuters in flooded subway lines and on a GO Train stuck on a track flooded by the overflowing Don River. To avoid an electricity blackout, Toronto residents are asked to reduce their electricity use because a key underground electricity station is flooded.

Spring 2017

Record flooding hits communities across Ontario forcing thousands to evacuate and causing hundreds of millions of dollars in insured damage:
• In Northern Ontario, many First Nations communities are harmed
• Shorelines along Lake Ontario and the St. Lawrence River experience record high water levels (a meter above normal) because of torrential rain, record runoff around the Great Lakes and an unusually warm winter.
• The Greater Toronto Area is hit hard, especially Durham Region and the Toronto Islands which are flooded and off limits for most of the summer.

August 2018

In Toronto, a highly localized “ninja” storm dumps over 100 millimetres of rain in less than two hours. It is so concentrated that weather forecasters and the TRCA don’t see the storm coming. The Rockcliffe Neighbourhood, along Black Creek, sees water levels rise by over two meters in just over an hour. The flood waters spill into nearby buildings, stranding two men in an elevator who are rescued by first responders just before the elevator is submerged.

Spring 2019

Floods devastate communities across southern Ontario because of heavy rains, sudden temperature rises and melting snow. Over 20 municipalities and one First Nation declare an emergency as properties and important infrastructure, such as roads and bridges, are damaged. In eastern Ontario, along the Ottawa River, record rain volumes lead to record water levels causing significant damage to property and infrastructure.


While most of the attention around flooding in Durham Region has recently focused on people living close to Lake Ontario, Durham residents living close to a river or in a neighbourhood with an inadequate stormwater system can also experience flooding.

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Toronto residents got a taste of the future in 2013 when almost 130 mm of rain fell in a couple of hours on a hot and humid July afternoon. Toronto’s aging stormwater system was just too small to handle the water. Shortly after the rain started, water entered subway and hydro stations, turned roads and transportation corridors into mini lakes and flooded countless basements.

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Water defines Niagara Region by the lakes that surround it and the canals and rivers that run through it. Residents know the power water has to shape Niagara, thanks to the mighty Falls: They also know the damage it can cause. Over the past few years, high river and lake levels have caused serious flooding from Fort Erie to the south to St. Catharines to the north.

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