Updated Watershed Conditions Statement: Flood Outlook – Lake Ontario Shoreline July 11


Updated Watershed Conditions Statement: Flood Outlook – Lake Ontario Shoreline

Posted July 11, 2019


The Hamilton Conservation Authority (HCA) is advising that Lake Ontario water levels continue to be significantly above normal, due to record inflows from Lake Erie and continued risk of flooding in the upper St. Lawrence River. 

There are no observations, reports, or expectations of significant shoreline flooding or erosion at this time.  Localized flooding and shoreline erosion may still be occurring in some low-lying sections of waterfront trails, in Cootes Paradise, and at marinas.

According to International Lake Ontario – St. Lawrence River Board information, the Lake Ontario daily average water level is currently 75.82 m IGLD85.  The recent peak daily average water level was 75.92 m IGLD85 (last recorded on June 15), which surpassed the previous record level (75.88 m IGLD85 in May 2017) by 4 cm.  Assuming average rainfall for this time of year, it is expected that lake levels will continue to slowly decline (in general) through the summer.

In of itself, current and forecasted lake levels are not expected to cause significant shoreline flooding hazards.

However, significant shoreline flooding and / or erosion hazards may possibly occur in the coming weeks, if substantial storm surge and wave action occurs.  Strong shore-bound winds occurring from the north, northeast, or east would pose the primary concern.  Based on current forecasts, no significant storm surge or wave action is expected over the next five days.

HCA wishes to remind residents to continue to exercise caution near lakefront areas during this time, as high water levels and / or wave action may pose significant erosion, flooding and public safety hazards. 

A close watch on shoreline and weather conditions is recommended.  HCA staff continue to monitor Lake Ontario wind conditions and lake levels closely.

Currently, the Lake Ontario daily average water level is approximately 75.82 m IGLD85, which is about 79 cm above normal for this time of year.  For reference, the HCA shoreline flooding hazard level used for planning and development review is 78.5 m (which includes a lake level of 76.00 m and 2.5 m of wave action). 

Lake Ontario water levels are expected to remain above normal over the summer months and into the fall.

This Watershed Conditions Statement (Flood Outlook) – Lake Ontario Shoreline is an update to the message issued June 28, 2019.  This updated message is in effect until Friday, July 26, 2019, at which time it will either be updated or cancelled.  HCA will issue updates prior to July 26 as warranted.

For further information or questions regarding this message, please contact:

Jonathan Bastien, Water Resources Engineering
905-525-2181 ext 138
Fax: 905-648-4622
jbastien@conservationhamilton.ca