{"id":859050,"date":"2026-08-15T13:20:27","date_gmt":"2026-08-15T13:20:27","guid":{"rendered":"https:\/\/www.newsbeep.com\/ca\/859050\/"},"modified":"2026-08-15T13:20:27","modified_gmt":"2026-08-15T13:20:27","slug":"really-extreme-situation-edmontons-wettest-summer-on-record-raises-questions-around-erosion","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/ca\/859050\/","title":{"rendered":"‘Really extreme situation’: Edmonton’s wettest summer on record raises questions around erosion"},"content":{"rendered":"

More than 26 years ago, the top of a riverbank in Riverbend came sliding down into the valley below, taking one home with it, and leaving two others hanging precariously over the edge. Those two were later demolished.<\/p>\n

Today, Edmontonians know the event as the 1999 Whitemud Road Landslide, one of the most prominent slope failures in the city’s history.<\/p>\n

Two decades later, the culprit of that natural disaster is having another big year. While no homes have fallen into the river, erosion from the city’s wettest season on record is causing similar failures and is affecting infrastructure across the city.<\/p>\n

For City of Edmonton geotechnical engineering general supervisor Paul Lach, the summer of 2026 is another landmark, serving as “a grim reminder” of the effects of such natural hazards.<\/p>\n

He recalls other tough years for rain over his long tenure with the city. The current season, however, takes the cake, and his department is now facing an oversized load of issues caused by the persistent precipitation.<\/p>\n

“We’re well prepared, but nevertheless, this is a really extreme situation,” said Lach.<\/p>\n

Lach said many city assets like roadways, bridges and trails have suffered distress or damage.<\/p>\n

So far, the bridge at 137 Avenue and Horseshoe Creek has had an embankment failure<\/a>, slope instability has impacted the High Level Bridge, and there has been a landslide below Saskatchewan Drive just west of Gateway Boulevard, along with several others.<\/p>\n

It’s been a perfect storm for such conditions. Lach said June brought longer periods of rain, which saturated the soil, and then July’s deluges pushed things over the edge.<\/p>\n

“Both of those things are the most important types of triggers for slope instability,” Lach said.<\/p>\n

According to University of Alberta engineering professor Renato Macciotta, erosion in Edmonton typically happens in two places. The first is when the river and creeks like Mill Creek are high and moving fast after long periods of rain, which can cause erosion along the larger embankments.<\/p>\n

The other is due to water coming downslope towards the river, usually referred to as run-off.<\/p>\n

\"A<\/p>\n

A section of bank has slumped under 98 Avenue at Scona Road, in Edmonton on Friday, Aug. 14, 2026.<\/p>\n

When it comes to both kinds, Macciotta said it’s possible to mitigate erosion through certain measures. Run-off, for example, can be channelled into protected sections and safely discharged elsewhere in the environment. With river erosion, it’s possible to use large rock blocks to prevent river water from eroding embankments or to use dams to slow or control the flow of water.<\/p>\n

There are other measures as well, and Macciotta said the city does a good job of being proactive when it comes to erosion issues, but such precautions can be costly and designing the most cost-effective system becomes a bit of a balancing act.<\/p>\n

“Right now, the challenge for the city with the available resources is, ‘What do I design for?'” Macciotta said.<\/p>\n

In general, it’s very difficult to predict embankment failures, Lach said. However, the city employs extensive monitoring and tools to keep an eye on things. For responses and repairs, Lach said the city prioritizes areas where infrastructure and people could be the most affected.<\/p>\n

When asked about a similar failure to the 1999 landslide happening again, Lach admits there is always risk when building at the top of the riverbank. However, the disaster led to ample discussion on the matter later, resulting in a 2010 policy that sets out rules and restrictions for what and how developments can be built in such spots.<\/p>\n

But while no homes have been claimed by the North Saskatchewan in a long time, the growing prevalence of extreme weather due to climate change could put pressure on decision-makers to spend more on preventing erosion in the coming years.<\/p>\n

“It does seem like there is potential for more extreme conditions with climatic changes, and that’s something we’ll have to continue to evaluate over time,” Lach said.<\/p>\n

Macciotta said climate change and extreme weather turn the issue of mitigating erosion into a moving target.<\/p>\n

He said from a mechanical perspective, it’s possible to make ties between weather changes and the likelihood of erosion and landsliding events. However, quantifying exactly what those changes look like is a difficult task.<\/p>\n

“That’s the real challenge,” Macciotta said.<\/p>\n

He and several groups at universities across Canada are now trying to tackle that exact problem, he said, so they can better project what kinds of natural disasters to expect with climate change, to better inform decision makers.<\/p>\n

\"The<\/p>\n

The road is completely washed out on 137 Avenue at Horseshoe Creek, between 199 Street and Starling Drive on Monday, July 27, 2026 in northwest Edmonton.<\/p>\n

Related<\/p>\n

lnewbigging@postmedia.com<\/a><\/p>\n

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