Flexibility in setting Lake Ontario outflows to continue

By on December 2, 2019

The International Lake Ontario – St. Lawrence River Board (Board), in directing Lake Ontario outflows, has been given the ability to continue deviating from the flow specified by Plan 2014.

The Board has had authority to deviate from Plan 2014 since May 7, after Lake Ontario rose above the high water trigger levels specified in a provision known as criterion H14. In light of the present extraordinary circumstances, the International Joint Commission (IJC) has given the Board authority to deviate from Plan 2014 even after Lake Ontario falls below the criterion H14 trigger levels.

The new authority extends until June 2020 when Lake Ontario is forecast to reach its seasonal peak.   

The International Lake Ontario – St. Lawrence River Board issued the following statement: 

We appreciate the IJC’s decision to authorize the Board to continue to deviate from Plan 2014 after Lake Ontario water levels fall below the criterion H14 upper trigger levels. The Board has been reviewing data from the past three years to better understand when potential opportunities to deviate from Plan 2014 might be available over the next several months, and what the effects of such deviations might be on water levels and interests throughout the Lake Ontario – St. Lawrence River system. Forecasts indicate that Plan 2014 outflows will be very high and at or near maximum values for several months. The IJC’s decision will allow the Board to further increase outflows when opportunities arise considering the impacts that these flow increases will have on other interests of the system. These opportunities are expected to remove a small amount of additional water from Lake Ontario to reduce the risk of high water in 2020. The Board stresses that while an outflow strategy can influence water levels, the main driver is weather, especially when wet conditions are as extreme as they were in 2017 and 2019. We will continue to communicate the outflow strategy as the Board identifies opportunities to deviate from Plan 2014.

Across the Great Lakes, water levels remain high and are forecast to continue to be high through at least the winter. Whether they remain high next spring will primarily depend on weather and water supplies. Lake Ontario is the only Great Lake that has a chance of getting near or returning to its long-term average by spring 2020. This possibility is directly related to the influence that water regulation can have on water levels if the conditions to accommodate high flows in the St. Lawrence River occur.   

The Board, in conjunction with its staff, 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 and posted to the Board’s Facebook page at https://www.facebook.com/InternationalLakeOntarioStLawrenceRiverBoard (English), and more detailed information is available on its website at https://www.ijc.org/en/loslrb.

Provided information