Cataraqui Conservation Issues a Shoreline Conditions Statement Due to Storm Surge

Cataraqui Conservation is issuing a Shoreline Conditions Statement today, advising municipalities and the public of a short-term rise in water levels forecast for Lake Ontario and the upper St. Lawrence River due to storm surge generated by sustained high winds.

The Surface Water Monitoring Centre (SWMC), who forecast storm surge on Lake Ontario, has provided the following information in a Provincial Flood Watch for Lower Great Lakes issued at 2:16 PM, June 17, 2026:

• Expect sustained southwest winds of 40 to 60 km/h over Lake St. Clair, Lake Erie and Lake Ontario Thursday and Friday as they veer from southwesterly to westerly.
• The sustained winds will create a small surge in the eastern end of Lake Ontario and Bay of Quinte, from 4 PM June 18 to the morning of June 20.
• Levels are forecast to reach or exceed 1.5 m above chart datum in Kingston and at the mouth of the St. Lawrence River.

Conditions:
The current Lake Ontario water level measured at 6:36 AM today at Kingston is 75.35 m IGLD85* (1.15 m above chart datum of 74.20 m). According to the SWMC, water levels are forecast to be elevated over the period from 4 PM June 18 to the morning of June 20, with water levels peaking at or above 75.70 m IGLD85 or 0.35 m above current water levels at Kingston and at the mouth of the St. Lawrence River.
The latest SWMC Lake Ontario storm surge modelling, which forecasts water levels as far east as about Gananoque, suggests that the highest water levels will be in the Howe Island and Gananoque area, reaching as high as 75.70 m the evening or night of June 18. After the expected peak on June 18, the Gananoque area may continue to experience water levels up to 75.60 m until the night of June 19 before they begin to fall back down, once sustained wind speeds diminish. SWMC does not forecast water levels for St. Lawrence River east (downstream) of the Gananoque area.
*International Great Lakes Datum of 1985 (IGLD85)

Risks:
During this short-term period of elevated water levels from wind generated storm surge and accompanying wave action, there is increased risk of localized flooding and erosion impacts to some properties. Fixed docks could become inundated. Caution is advised near shorelines where there is potential for damage 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 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) Saturday, June 20, 2026, at 10 AM. A separate Shoreline Conditions Statement, issued June 12, 2026, also remains in effect.
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