Toronto power grid unprepared for extreme weather: researchers

Last week's rain storm disrupted power for tens of thousands of Torontonians, and as extreme weather becomes more common, Toronto's grid will have to adapt, climate researchers say. 

Ryan Ness, director of adaptation research at the Canadian Climate Institute, says utilities need to start preparing for more extreme weather so people don't lose power during increasingly common storms.

"These systems were often designed to be very, very strong and resilient based on the climate of the past," he said in an interview.

Toronto Hydro has looked at flooding risks in recent years, Ness said, but there hasn't been enough action.

"Presumably they are working on protecting those substations and other vulnerable electrical system componentry," he said. "But of course, we're seeing continued power outages in these kinds of extreme storms, so obviously there's still more to do."

Heavy rains on July 16 caused flash floods that took out power for nearly 170,000 customers in the city, according to Hydro One. Almost 100 millimetres of rain fell that day, equalling about a month's worth of precipitation.

The loss of power closed offices, restaurants and children's camps and made the commute home more difficult as traffic signals went out.

WATCH | Toronto mayor wants stormwater flooding solutions: 

Toronto mayor wants stormwater flooding solutions

4 months ago

Duration 1:54

Toronto Mayor Olivia Chow wants city staff to come up with solutions to better prepare the city for flooding during significant storms, like the one that hit the region on Tuesday. That includes looking into large infrastructure programs and ways for homeowners to better protect their properties. CBC's Dale Manucdoc has the story.

In an emailed statement, Toronto Hydro said it's been working to make its infrastructure more flood resistant, but this month's outages were the result of affected Hydro One equipment. Hydro One supplies power for Toronto Hydro to distribute to customers. 

Hydro One declined requests for an interview, but did provide comment on last week's outage, saying a transmission station had been affected by flooding.

"While all of the power supply has been restored to Toronto Hydro, our work at the affected station will continue over the coming days as crews make the repairs needed to return the station to its normal operation," spokesperson Tiziana Baccega Rosa said in an email.

"We will also work to identify the cause of the outage and look at what actions we need to take to prevent future outages and make our system more resilient to extreme weather."

Warnings of more severe storms have been coming for over a decade. 

In 2013, an even bigger rain storm caused floods that led to evacuations, and roughly 800,000 customers lost power. At the time, experts were already saying urban flooding was likely to get worse as the climate changed. 

Flooding 'predictable,' says professor

Jason Thistlethwaite, an associate professor who studies the economic impact of climate risks at University of Waterloo, says although fewer customers were affected by this month's storm, critical infrastructure is still too vulnerable.

"That one issue led to 170,000 people losing electricity," he said. He says critical infrastructure needs to be moved above the flood plain and any underground infrastructure needs to be strengthened against flooding.

"This won't be the first time those stations have been wet. You know it happens there. It's a low-lying area. It's predictable and there are maps and models that you can use." 

The city of Toronto has a "risk-specific plan" for responding to power disruptions, city staffer Laura McQuillan said in an email, but responsibility for the grid lies with Toronto Hydro and Hydro One.

The Ontario Energy Board, the province's regulator, filed a report to the Minister of Energy last year, looking at how to improve resilience and responsiveness in electricity distribution. The report notes flooding is a risk to infrastructure and recommends ways to make distribution systems more resilient, including by raising substations. 

"Work is now underway to enhance the sector's capability to anticipate and respond to adverse weather," OEB spokesperson Mary Ellen Beninger said in an email.

The Ministry of Energy, a major shareholder in Hydro One, did not make anyone available for comment, but in an email, spokesperson Isha Chaudhuri said last year the province directed the OEB to "ensure local electricity distributors are strengthening their systems so that electricity supply is reliable whenever people need it across Ontario."