Drought Conditions Continue in Great Lakes – St. Lawrence River System - International Lake Ontario – St. Lawrence River Board to Continue Deviations


The drought conditions that have impacted the Great Lakes-St. Lawrence River watershed this spring have continued to persist into the summer.  The North American drought monitor maps show abnormally dry to moderate drought conditions within most of the basin, both upstream (around Lake Erie and Lake Ontario) and downstream (along the St. Lawrence River) https://www.ncdc.noaa.gov/temp-and-precip/drought/nadm/maps.

The water level of Lake Ontario has remained stable in June. Unless the basin receives significant rainfall, it is likely that Lake Ontario is approaching (or has already reached) its seasonal peak or maximum level.

As a result of the drought conditions, lake levels reached critical low levels defined by Plan 2014 criterion H14, which is the trigger that allows the Board to deviate from plan-prescribed flows. The Board began deviating from flows prescribed by Plan 2014 (Plan flows) by reducing Lake Ontario outflows on May 29th.  The Board is currently operating under the Plan’s low Criterion H14 deviation authority which is expected to apply at least into July.   The Board will continue with the current low water deviation strategy of flow reductions of 200 m3/sec (7,060 cfs) below Plan flows for the foreseeable future.

It is important to remember the ability for the Board to influence water levels within this natural system is in the realm of centimeters and inches, not meters and feet.  Lake levels are largely dependent on inflows received from Mother Nature, namely precipitation”, said Mr. Steve Durrett, United States Co-Chair of the International Lake Ontario – St. Lawrence River Board.  The Board will continue to monitor conditions and the effects of the deviation strategy closely while simultaneously tracking weather forecasts and drought conditions. Deviations from Plan flows under the low Criterion H14 threshold are meant to “provide all possible relief to municipal water intakes, navigation and power purposes, upstream and downstream.”  The deviations are expected to decrease the risk of excessive low water levels caused by dry summer conditions. However, outflow management cannot eliminate the risk of extreme water levels from occurring during periods of severe weather and water supply conditions.

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, and more detailed information is available on its website at https://www.ijc.org/en/loslrb.

The Board held virtual public presentations on current and forecast conditions last week. Recordings of these presentations are available here: https://ijc.org/en/loslrb/videos.



Bryce Carmichael:  (513) 418-8562                   

Sarah Lobrichon:  (613) 794-8592

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The International Lake Ontario-St. Lawrence River Board ensures that outflows from Lake Ontario meet the requirements of the International Joint Commission's Orders of Approval. Under any regulation plan, the ability to regulate the outflow from Lake Ontario does not mean that full control of lake levels is possible. This is because the major factors affecting water supply to the Great Lakes, precipitation, evaporation, and runoff cannot be controlled, and are difficult to accurately predict.