Flood forecasting: Inside Ontario Power Generation’s tools and tactics
Cathy Fox
Local Journalism Initiative
Published February 26, 2025.
OTTAWA VALLEY – Ontario Power Generation (OPG) held a public Zoom presentation on the Ottawa watershed, revealing the tools they use to monitor and manage flood levels. The watershed, shared by Quebec and Ontario, is twice the size of New Brunswick. Six hydroelectric generating stations on the Ottawa River are managed by a control centre
in Cornwall, Ontario.
The control centre operates 24/7, using real-time data from the stations. About 300 employees oversee operations, with six to eight employees on the road to respond to emergencies. Each station employs 20 to 30 full-time staff trained to respond to alerts.
A variety of measuring tools ensure continuous data transmission to the central hub
in Cornwall.
Through illustrated charts, OPG explained the limited ability to prevent flooding when high water volumes occur due to precipitation and temperature. Large reservoirs capable of storing significant water volumes are located upstream, while many water sources feed into the river further downstream. There is no suitable location for a reservoir lower down the river. Natural constrictions and shallower areas also contribute to water backups and faster flooding.
Although OPG can mitigate flooding effects during typical spring freshets, they can only provide a short window of warning for high water levels—usually about 12 hours. However, they can predict extreme events using historical data to help communities be more proactive. Recent data shows that the last six years of wet conditions followed a 20-year dry period. OPG anticipates either extreme due to a similar trend observed from the 1920s to the 1930s. Despite this, the likelihood of severe flooding is estimated at just one per cent, or one in 100.
During the presentation, a participant expressed disappointment that no solutions were offered for dealing with previous flood damages. OPG suggested using flood maps and data available on the Ottawa River Regulation Planning Board (ORRPB) website to assess local risks. They also recommended following building guidelines in flood zones and restoring wetlands as natural buffers to absorb excess water.
In Quebec, the Ministry of the Environment oversees waterway protection, while the Sécurité Civile et Centre des Opérations Gouvernementales provides citizen guidance.
OPG referred to a related slideshow, Ottawa River Overview of Management, available
on YouTube from March 2022. For updates during high water events, visit OPG.ca
or the ORRPB at www.ottawariver.ca.
