Published on Mar. 4, 2026, 3:29 PM
Deep in the snowpack north of the Greater Toronto Area, a silent danger lurks and prepares to be unleashed.
I love a melodramatic beginning, but it’s not entirely off base. The winter of 2025/2026 has been exceptional compared to the last few years. Colder and snowier than average has meant that the snowpack is deeper and more saturated than we’ve seen in a while.
All that snow and water is runoff fuel and that then translates into the potential for ice jams and associated flooding anywhere along the various watersheds that drain through the Greater Toronto Area. To find out how significant the problem might be, I contacted David Kellershon, Associate Director of Engineering Services at the Toronto Region Conservation Authority.
SEE ALSO: Watch for falling ice as temperatures climb above the freezing mark
David explained to me, “We’ve had a long cold spell, and that means that we’ve had the rivers freeze up a little more so than other years. We have the equivalent of 80 mm of water sitting on our landscape, and the danger is that if it melts quickly, it’s the same as an 80-year storm hitting the watershed of the rivers.”
The good news is that we’ve had a bit of a melt in late February, and that’s reduced the amount of ice on the rivers, lessening the chances for ice jams and flooding. Despite that, enough ice remains on the rivers to create jams if the melt happens fast enough, and especially if the warmth is accompanied by rain.
The TRCA is monitoring a number of spots along the watersheds, specifically at tight corners and shallow spots. Combined with vulnerable urban areas, there are around 20 significant areas that TRCA is watching closely and a list can be found on the TRCA website.
“One of the spots we watch closely is Bolton. That was the last place we had an ice jam and flood and where the city had to evacuate 80 homes. Ice and water came into the downtown core. What happened there was that the ice started breaking up, jammed up, the water built up behind it and flooded the town. The Old Mill area is another spot where jams happen and people often go there to see it because it’s a drainage river for about 900 square kilometres. The ice build up can be very significant.”