Lake Ontario water levels break 2017 record as we approach ‘new normal’

International Joint Commission Lake Ontario tour
IJC Commissioners and staff listen to James Dann, Toronto waterfronts and parks manager, during a June 5 tour of water levels on Toronto Island. Photo Credit: International Joint Commission

As the calendar turned to June, Lake Ontario broke its all-time water level record, reaching heights of 75.90 metres and surpassing the record total set in 2017.

Following the setting of the record, Lake Ontario water levels have started to stabilize due to decreased precipitation and increased Lake Ontario outflows, according to the International Joint Commission (IJC), which monitors boundary water issues.

“Extraordinarily high outflows combined with forecasts of warmer, drier conditions later this week, make it likely that Lake Ontario is at or very near its peak level this year,” IJC reported in a statement. “Any additional rise is likely to be small, less than 3 cm, depending on rainfall, and there is a good chance levels will remain stable or even start to decline slowly next week,” the commission added.

Record precipitation caused the record high water levels in 2017, which reached 75.88 metres. It also led to record inflows from Lake Erie and the Ottawa River system, resulting in new record highs this year.

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Outflows reached 10,000 m3/s (353,100 cfs) on June 5, close to the highest on record, and further increases are expected.

“Such conditions are uncontrolled and highly unpredictable, and this has always been the case,” IJC officials said in a statement. “The new normal is that we must make the preparations for the next event a part of everyday practice and planning, even though it is becoming especially difficult to know how soon that next event will be.”

Updates on Lake Ontario water levels can be found here.


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