St. Lawrence River water levels to remain above seasonal average

Handout from SNC
St. Lawrence River water levels to remain above seasonal average
Cornwall's Moses-Saunders Dam during a summer month (Nick Seebruch/ Seaway News).

ST. LAWRENCE SEAWAY, Ontario -SNC continues to caution residents along low-lying areas of the St. Lawrence River in the Township of Augusta, Township of Edwardsburgh/Cardinal, and the Township of South Dundas.

According to the International Lake Ontario – St. Lawrence River Board“The Lake Ontario outflow will be maintained at a steady rate of 10,400 m3/s. This follows the completion of a successful evaluation period, which started on Wednesday of last week to allow the Board and stakeholders to monitor any effects this high flow may have. Lake Ontario’s lake-wide average water level is also now declining from where it was at its peak near the end of May. The recent rate of decline has been slightly less than 1 cm per day, and this is expected to continue in the coming days with generally warm weather and little precipitation forecasted.”

Environment and Climate Change Canada forecasts average precipitation over the next 3 months. St. Lawrence River water levels upstream of the Moses-Saunders Dam in Cornwall will continue to slowly decline, but they’ll remain relatively high and above the seasonal average for several more weeks and possibly into the fall.

Wind may cause higher waves, further aggravating water levels which may affect structures closer to the shore. 

Residents are advised to stay away from watercourses where flows are high and where banks might be unstable.  Parents are encouraged to explain these dangers to their children.

Staff will continue to monitor the water levels and weather forecasts as part of the Flood Forecasting and Warning Program and will provide updates in the event conditions change.


The public is encouraged to visit and to also report changes in water-related conditions, soil stress fractures (i.e. cracks in soil), abrupt changes in streambanks, or sudden leaning of trees in their local areas. All feedback and photos can be sent to, posted on our Facebook page (/SouthNationConservation), or Tweeted to us (@SouthNationCA).

For more information please contact the Flood Duty Officers: Jason Symington at 613-984-2948 ext. 230 or Michael Jones at 613-984-2948 ext. 310.

This statement is in effect until Monday, July 31, 2017.

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