UPDATE: Shoreline Conditions Statement Flood Outlook for Lake Ontario - Static Water Level

Cataraqui Conservation is issuing an update to its Shoreline Conditions Statement today, advising municipalities and the public of stabilizing water levels on Lake Ontario and the upper St. Lawrence River.

The International Lake Ontario – St. Lawrence River Board (ILOSLRB), who manage Lake Ontario outflows and forecasts water levels, reported the following in their May 11, 2026, briefing:

• The lake-wide average water level of Lake Ontario has remained generally stable at 75.35 m since Thursday, May 7
• Declining Ottawa River outflows have allowed the Lake Ontario outflows to be increased

Conditions:

The Lake Ontario water level measured today at Kingston is currently 75.32 m IGLD85* which is 0.82 m below the 1:100-year flood elevation of 76.14 m IGLD85.

The current level of the St. Lawrence River measured at Brockville is 75.00 m. This is 0.72 m below the 1:100-year flood elevation of 75.72 m IGLD85 in that area along the river.

Lake Ontario water levels are expected to remain relatively stable for the next couple of weeks, around the elevation of 75.35 m, before beginning a slow decline.

The latest Lake Ontario water level forecast (updated on Thursdays) is available from ILOSLRB.

*International Great Lakes Datum of 1985 (IGLD85)

Risks:

While water levels have stabilized, they could be sustained at about 0.30 to 0.35 m (30 to 35 centimetres) above typical summer peak for a couple of weeks before a slow decline will commence. Above normal levels are expected to persist through the summer and into the fall. During periods of elevated levels there remains an increased risk of localized impacts from wave action.

Widespread flooding is NOT expected at this time. However, if you witness flooding and/or require assistance your first point of contact is the local municipality.

Staff will continue to monitor ILOSLRB forecasts and Surface Water Monitoring Centre (SWMC) Provincial Statements, and update Cataraqui Conservation messaging as needed. This Shoreline Conditions Statement will remain in effect until (or updated before) Friday, June 12, 2026, at 11:59 PM.

For more information from the ILOSLRB:

• Water levels (updated every weekday): https://ijc.org/en/loslrb/watershed/water-levels
• Flows (updated every weekday): https://ijc.org/en/loslrb/watershed/flows
• Lake Ontario forecast (updated on Thursdays): https://ijc.org/en/loslrb/watershed/forecasts
• Lake Ontario outflow changes (updated in real time as flow changes occur): https://ijc.org/en/loslrb/watershed/outflow-changes#flow_table
• Plan 2014 F limit: https://ijc.org/en/loslrb/watershed/faq/4#4-8-2
• Criterion H14 triggers authorizing deviations: https://ijc.org/en/loslrb/watershed/faq/4#4-8-1
• Ottawa River conditions and forecast (updated daily during freshet): https://ottawariver.ca/

For up-to-date Lake Ontario and upper St. Lawrence River water levels in your area visit the following Government of Canada links:

• (Kingston) https://tides.gc.ca/en/stations/13988/2026-04-29?tz=EDT&unit=m
• (Brockville) https://tides.gc.ca/en/stations/14400/2026-04-29?tz=EDT&unit=m
• Marine Weather forecasts for Eastern Lake Ontario and upper St. Lawrence River:
• https://weather.gc.ca/marine/forecast_e.html?mapID=11&siteID=08203 (Eastern Lake Ontario)
• https://weather.gc.ca/marine/forecast_e.html?mapID=11&siteID=07200 (Kingston to Cornwall)
• For further information on current provincial flood messaging visit www.ontario.ca/flooding
• For up-to-date flooding information, please visit our flood forecasting and information page at https://cataraquiconservation.ca/pages/flood