Edmonton’s stormwater system strained after repeated heavy rain

Edmonton's roads are once again facing flooding and damage, as crews work to repair sinkholes and infrastructure battered by almost two months of relentless heavy rain. The city's stormwater system is critically strained, and EPCOR, the utility provider, stated on Tuesday that a period of dry weather is essential for its recovery.

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The cumulative effect of those is that the system, essentially, doesn’t have time to recover completely, i.e., drain the water away from stormwater management facilities.

The cumulative effect of multiple heavy rainfall events, from a prolonged deluge in June to recent intense thunderstorms, has overwhelmed the system. "The system, essentially, doesn’t have time to recover completely, i.e., drain the water away from stormwater management facilities," explained Craig Bonneville from EPCOR’s project planning department. With the ground saturated, its ability to absorb water is diminished, leading to increased runoff flowing into drains and exacerbating flooding in underpasses and on roads, causing sinkholes to appear across the city.

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These pipes, we don’t see them, but we depend on them every day.

Alireza Bayat, a professor of civil and environmental engineering at the University of Alberta specializing in underground infrastructure, pointed out that the recent storms have exposed vulnerabilities in Edmonton's aging stormwater network. "These pipes, we don’t see them, but we depend on them every day," Bayat said, noting that infrastructure built in the 1960s and 70s is now tasked with handling precipitation levels associated with 2026 weather patterns and climate change. He added that extreme weather events invariably reveal inadequately maintained infrastructure, highlighting that "the weak points are typically unmaintained points."

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Always, these types of events find the weak points, and the weak points are typically unmaintained points.

While acknowledging that infrastructure replacement is a lengthy process, Bayat stressed the importance of maximizing the efficiency of existing systems through diligent maintenance and operational improvements. "We are left right now with the infrastructure we have, so we have to use them better, maintain them better," he urged. The city has been inundated with calls, receiving over 1,400 reports of flooding and storm damage in the past week alone. In 2019, Edmonton city council approved a $1.6 billion initiative to bolster the stormwater system's resilience, a move Mayor Andrew Knack explained was necessary as "what used to be a one-in-100-year flood is now one-in-10-year flood." He conceded in hindsight that efforts to enhance flood resilience should have commenced decades earlier.

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We are left right now with the infrastructure we have, so we have to use them better, maintain them better.