GRCA Issues Flood Warning Update

Flood Potential: High

The Ganaraska Region Conservation Authority advises that water levels on Lake Ontario have stabilized 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 has declined, outflows from Lake Ontario have been increased and are flowing at maximum rates considering navigation and downstream flooding.

With no rain currently in the forecast, outflows from the lake will continue to exceed inflows from Lake Erie and watershed runoff, which will allow the water level of Lake Ontario to gradually decline.

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 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 Friday, June 16th, 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.