GRCA Issues Flood Warning Update – Lake Ontario Shoreline

Flood Potential: High

The Ganaraska Region Conservation Authority advises that water levels on Lake Ontario are stabilizing and should start to decline over the next week or two albeit at a very slow rate. Having reached record elevations, it will take several weeks for the water levels to recede below critical flood thresholds. The potential for shoreline flooding and erosion will remain for now, especially during periods of high winds and wave action.

Heavy rainfall in April and May has caused the increase in water levels, while severe flooding in the St. Lawrence and Ottawa Rivers prevented a greater release of water from Lake Ontario. Now that the Ottawa River is declining, outflows from Lake Ontario are increasing.

The water level of Rice Lake peaked on Monday and has since receded by 11cm. While still above normal for this time of year, levels will continue to decline providing relief to residents affected by flooding. Therefore, the flood warning for Rice Lake has ended and so this flood warning applies to Lake Ontario only.

A rainfall event is forecast for this Sunday, however it is not expected to cause significant runoff or reverse any declining trends in water levels. The main concern will be if a southerly wind picks up with the movement of the weather system this weekend.

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

This Flood Warning for the Lake Ontario shoreline will be in effect through Sunday, May 31st, 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 Warning is issued as notice that flooding is imminent or already occurring in specific watercourses or municipalities.