Cataraqui Conservation issues updated flood outlook for Lake Ontario & Upper St. Lawrence River

Water levels along Lake Ontario and the upper St. Lawrence River have stabilized following recent high-water conditions, though conservation officials say residents near the shoreline should continue to watch for potential impacts from waves and elevated water levels through the summer.

On Wednesday, May 13, 2026, Cataraqui Conservation issued an updated shoreline conditions statement advising municipalities and residents that widespread flooding is not expected at this time.

According to the authority, the lake-wide average water level on Lake Ontario has remained generally stable at 75.35 metres since May 7, based on recent information from the International Lake Ontario–St. Lawrence River Board.

Cataraqui Conservation says Lake Ontario levels are expected to remain relatively steady over the next several weeks before beginning a gradual decline. However, they warn that water levels are still roughly 30 to 35 centimetres above a typical summer peak and could remain above seasonal averages moving into the fall.

In Brockville, water levels along the St. Lawrence River were measured at 75 metres — about 0.72 metres below the area’s 100-year flood threshold.

Officials say no widespread flooding is anticipated, but residents experiencing shoreline flooding or requiring emergency assistance should contact their local municipality and monitor the latest water level forecast available from ILOSLRB.

Cataraqui Conservation said staff will continue monitoring forecasts and provincial water conditions and will update the advisory as needed. The shoreline conditions statement will remain in effect until June 12.