The International Lake Ontario – St. Lawrence River Board will Increase Outflows through the Moses-Saunders Dam from October 16 through mid-December
Lake Ontario outflows will be increased by 200 m3/s (7,100 cfs) above the amount set by Plan 2014, beginning October 16. This will continue for approximately eight weeks to return water levels in Lake Ontario to the level it would be had outflow deviations not been required earlier this year.
Drought conditions in spring 2021 caused water levels on Lake Ontario to decrease below the Criterion H14 major deviation threshold. As required by the International Joint Commission’s (IJC) Directive, the regulation plan needs to be followed unless water levels reach any of the defined triggers specified in the directive. Therefore, the International Lake Ontario-St. Lawrence River Board decreased outflows from May 29 through July 16, 2021, until water levels on Lake Ontario increased above the Criterion H14 major deviation threshold. The summer deviations maintained an extra 4 cm (1.6 in.) of water on Lake Ontario relative to Plan 2014. In addition to the summer deviations, the Board decreased outflows from October 8 through October 11 under the minor deviation authority as defined in the IJC’s Directive. The October deviation was made to improve conditions on Lake St. Lawrence for boat owners to remove boats at the end of the boating season. The October minor deviation caused an increase of approximately 0.8 cm (0.3 in) of water on Lake Ontario, compared to Plan 2014. The summer and fall deviations resulted in a combined total deviation of 4.8 cm (1.9 in). The increased outflows scheduled from mid-October through mid-December will remove the 4.8 cm (1.9 in) of water that was maintained on Lake Ontario. The Board expects to return to Plan 2014 prescribed outflows in mid-December.
“In accordance with the Directive, the Board must obtain IJC approval for strategies to return to plan flows through what is known as equivalent offsetting deviations, or payback”, said Mr. David Harper, Canadian Co-Chair of the International Lake Ontario-St. Lawrence River Board. The Board received approval from the IJC for the offsetting deviation strategy on October 12th. The Board maintains a record of all deviations and the amount of water that is temporarily maintained or removed from Lake Ontario. “Lake Ontario remains a natural system and is not a reservoir”, said Mr. Steve Durrett, United States Co-Chair of the International Lake Ontario-St. Lawrence River Board. The record-keeping system for deviations operates like a check book that is eventually balanced and enables the Board to return the system to the water levels that would have occurred under Plan 2014 after outflows have been influenced as required by IJC’s Orders and Directive.
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 the website at https://www.ijc.org/en/loslrb. Frequently asked questions are available at https://ijc.org/en/loslrb/watershed/faq/4.
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.