Board eyes less-extensive Lake Ontario flooding

This file photo from last year shows a sign warning visitors to the Lake Ontario shoreline about high water levels that created flooding problems along the lake in 2019. The International Lake Ontario - St. Lawrence River Board is predicting rising water levels on Lake Ontario this spring, however the international body says current forecasts suggest the levels may not be as high as they were in 2017 and 2019.

The International Lake Ontario - St. Lawrence River Board is predicting rising water levels on Lake Ontario this spring, however the international body says current forecasts suggest the levels may not be as high as they were in 2017 and 2019. 

The regulatory agency noted on Wednesday that Lake Ontario has been rising gradually for the past couple of weeks, but very slowly recently. As of Monday, the water level on Lake Ontario was 72.26 meters (246.92 feet), which is 42 cm above average but 38 cm below the record high for this time of year. 

The regulatory board says it expects both Lake Erie and Lake Ontario to continue their seasonal rises in the coming days and weeks. It also indicated that Lake Ontario outflow remains high currently, despite recent reductions necessary to address lower St. Lawrence River levels and outflow will continue to be maximized to the extent possible.

With cooler temperatures currently forecast for the next two weeks, along with anticipated precipitation events, the board expects slow melt of existing snowpack to continue.

"While it is still early, at this point in the season, there are positive signs beginning to emerge that suggest more favorable conditions this spring than during the high water years of 2017 and 2019," the board said in a statement issued Wednesday. "The worst-case scenarios are starting to look less likely."

Representatives from the board said they are closely coordinating with the Ottawa River Regulation Planning Board during the Ottawa River snowmelt to have the highest outflow from Lake Ontario while balancing impacts upstream and downstream on the St. Lawrence River.

In addition, the board reported the following: 

• March Lake Ontario outflows were again a new record for the month, the third straight month of record-high outflows under the International Lake Ontario – St. Lawrence River Board’s deviation strategies;

• the delayed opening of the St. Lawrence Seaway, in combination with seasonable weather and favorable conditions in the Ottawa River basin, allowed the board to remove an extra 3.46 cm from Lake Ontario. This would not have been possible had the Seaway opened on March 20;

• the Ottawa River freshet began around mid-March, but only really picked up following heavy rain and mild temperatures around March 27, the weekend immediately before Seaway opening;

• Ottawa River flows have remained elevated since the start of the freshet, and have been increasing recently owing to some occasional scattered precipitation, but also very mild temperatures and significant snowmelt.

• some other large tributaries to the lower St. Lawrence River have also been increasing, and this, along with the high outflows from Lake Ontario, has raised water levels at Lake St. Louis and at Lake St. Peter to their minor flood levels.

 

Information on hydrologic conditions, water levels and outflows, including graphics and photos, are available on the board's website at www.ijc.org/en/loslrb

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