Flood Outlook Statement: Saint Lawrence River

18-Apr-2019 18-Apr-2019

Weather Forecast: Forecasts indicate that two low pressure systems will be combining to produce significant rainfall of 50 to 65 mm and warmer temperatures over much of the Ottawa River basin beginning on Thursday, April 18 through to Saturday, April 20, 2019.

Environmental Conditions: While Lake Ontario’s current water level is above average, it is still well within the historical range of observed levels at this time of year and currently well-below the extreme highs of 2017.

Risks: Ottawa River flows are forecasted to increase rapidly and significantly over the next several days in response to a major storm system, with heavy precipitation, mild temperatures and significant snowmelt expected.

As a result, the International Lake Ontario – St. Lawrence River Board is reporting potential for a significant and relatively rapid rise in Lake Ontario water levels, particularly during the next two weeks, and levels may rise well above seasonal average values; Ottawa River flows have an effect on lower St. Lawrence River levels and on Lake Ontario outflows.

ACTION: Continued vigilance remains critically important; residents are advised to stay away from rivers as the forecasted weather may rapidly increase river flows and banks might be unstable and slippery. Parents are encouraged to explain these dangers to their children.

Residents in flood prone or low-lying areas historically susceptible to flooding are encouraged to closely follow evolving conditions, and should also take the necessary precautions to protect their property, such as:

  • Ensuring sump pump is clear, in good working condition and has a backwater valve on it
  • Portable generator and backup pump
  • Ensuring downspouts are clear and the outlet is at least 3 m from the dwelling
  • Removing or securing items that might float away as flows increase
  • Removing valuable items from basements or lower floors that could be subject to flooding
  • Keep emergency phone numbers handy
  • Familiarize yourself with your municipality’s emergency preparedness plan

Duration: This statement is in effect until Tuesday, April 23, 2019.

SNC monitors the water levels and weather forecasts as part of the Flood Forecasting and Warning Program. Updates are provided as conditions change.

The International Lake Ontario – St. Lawrence River Board continues to monitor conditions on an ongoing basis. Information on hydrologic conditions, water levels and outflows, including graphics and photos, are available on the Board’s website at

Please visit for more information. To provide feedback with respect to changes in water related conditions please email, posted on our Facebook (/SouthNationConservation) or Twitter (@SouthNationCA).

FOR MORE INFORMATION: Jason Symington, SNC Environmental Technologist,

FOR MEDIA INQUIRIES: John Mesman, SNC Team Lead of Communications,

Forwarded to: All Flood Forecasting and Warning Directory