GRCA Cancels Flood Warning and Issues Flood Watch

Flood Potential: High

The Ganaraska Region Conservation Authority advises that water levels on Lake Ontario have been slowly declining since reaching their peak on May 26th. A Flood Warning was first issued on May 5th when heavy rains caused the already high lake level to rise sharply due to runoff from the surrounding watersheds. The slow moving storm dumped 75 to 80mm of rain in some areas and caused widespread flooding across much of Ontario and Quebec.

Recent dry weather is helping to reduce inflows from the surrounding watersheds, while record high outflows are working to slowly bring down the lake levels. So far the lake level has declined by 12cm at Cobourg but it still remains more than 70cm above normal for this time of year. Continued slow declines in water levels are expected for the next several weeks to months as high flows are released into the St. Lawrence River.

Water levels are still critically high and winds from a southerly direction will continue to be a concern as wave action in combination with high water levels may result in significant shoreline erosion and flooding in low-lying areas especially where streams meet the lake.

Eroding shorelines, submerged beaches, flooded marinas and wetlands on Lake Ontario will continue to be hazardous with potentially unstable banks. Residents are asked to exercise caution around our shorelines and to alert any children in their care of these dangers.

This Flood Watch for the Lake Ontario shoreline will be in effect through Friday, July 7th, 2017. Conservation Authority staff will continue to monitor conditions, and provide updates as necessary. Should you have any questions or wish to report flooding, please contact the following GRCA staff at 905-885-8173.

Mike Smith
Flood Operations Officer

Mark Peacock, P.Eng.
Flood Forecasting and Warning Coordinator

Note: A Flood Watch is issued as notice that flooding is possible in specific watercourses or municipalities. Municipalities, emergency services and individual landowners in flood-prone areas should prepare.