Major flood levels possible along Ottawa River, conservation authorities warn
Posted Apr 16, 2026 01:35:36 PM.
Last Updated Apr 16, 2026 04:05:43 PM.
Residents along the Ottawa River are being asked to stay vigilant over the next few days as water levels are expected to rise, possibly escalating to a major flood in low-lying areas, the conservation authorities warn.
In a memo, the three agencies that govern the waterways around the nation’s capital — Rideau Valley, Mississippi Valley and South Nation conservation authorities — issued a plea to property owners to take precautions ahead of the weekend.
Experts believe that with the constant rain over the last week, and more expected, it is possible that areas downstream of Britannia to Hawkesbury could experience minor flood levels in the next few days. However, as of Monday, some locations could see major flood levels.
From Arnprior to Britannia, minor flood levels are expected in some areas on Thursday, with levels exceeding the major category by the weekend.
Major vs minor flooding defined
Minor flooding: Defined by RVCA as the level at which parts of some streets, lawns and parks begin to flood, with no or few buildings being affected
Major flooding: Defined as the level at which parts of one or several streets begin to flood, with several buildings and neighbourhoods impacted
The authorities are telling people in flood-prone areas to follow the changing conditions and prepare, including making sure sump pumps are clear, a backup generator is available, downspouts, driveways and culverts are clear, and securing items outside that could float away.
“Residents are advised to stay away from watercourses where flows are high and where banks might be unstable,” the memo reads.
This comes on top of warnings from Environment Canada saying the ground in the valley cannot absorb much more water.
The forecast predicts that 10 to 20 millimetres of rain will fall on Thursday, prompted by significant systems travelling across the region. The ground is already saturated with days of rain leading up.
Both Saturday and Sunday, there is rain in the forecast.
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