Moses Saunders Dam

Lake Ontario outflows to be maintained above navigation limit


The Board is actively exploring deviating beyond an outflow of 10,400 m3/s (367,270 cfs) reached on June 13th, with the intent to provide relief to shoreline stakeholders upstream of the Moses-Saunders Power Dam.

Before undertaking higher flows, the Board is communicating with stakeholders to assess the impacts of these additional flows, to provide them an opportunity to prepare if outflows are increased.

Outflows reached 10,400 m3/s (367,270 cfs) on June 13th, which is the maximum flow that was attained in 2017 and the maximum sustained flow on record. The navigation industry is being notified that the Board is exploring regulatory strategies that include increasing flows above the current outflow.

Though outflows are very high, it is expected that lake levels on Lake Ontario will continue to remain high for the next several weeks.

The Board recognizes that the flooding is impacting many people’s homes, businesses and lives. We are working to reduce flooding impacts upstream and downstream to the extent possible.

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 (English), and more detailed information is available on its website at


Rob Caldwell: (613) 938-5864;

Andrew Kornacki: (716) 879-4349, (716) 352-8669;


The International Lake Ontario – St. Lawrence River Board specifies the outflows from Lake Ontario, according to Plan 2014 as required in the 2016 Supplementary Order from the International Joint Commission. This plan was agreed to by the United States and Canada in December 2016 in an effort to improve environmental performance while maintaining most of the benefits provided to other interests by the previous Plan 1958-D, which was in use since 1963. In determining outflows, the Board, in conjunction with its staff, pays close attention to water levels in the Lake Ontario-St. Lawrence River system and on the Great Lakes upstream, and to the effects on stakeholders within the basin.

Water levels vary from year-to-year and throughout the year depending on weather and water supply conditions.  Such variations benefit coastal wetlands and are critical to a healthy lake environment, but may at times and depending on individual circumstances increase the vulnerability of shoreline structures and reduce opportunities for recreational boating activities.  The Board urges everyone to be prepared to live within the full range of levels that have occurred in the past and of those that may occur in the future.  Based on historical observations and projected future conditions, at a minimum, Lake Ontario water levels are expected to range from a high of 75.88 m (248.9 ft.) to a low of 73.56 m (241.3 ft.) at infrequent intervals.  However, it is also recognized that future climate conditions are uncertain, and more extreme water levels may be reached and these extremes may occur more often.  Levels on the St. Lawrence River tend to vary more widely than on Lake Ontario.  Also, these levels do not include the varying local effects of strong winds and wave action that significantly increase or decrease local water levels on both the lake and river, with temporary changes of over half a meter (two feet) possible in some locations.

For more information, please see the Board’s website ( and Facebook page ( receive a weekly email about water levels and flows in the Lake Ontario–St. Lawrence River system, please send a blank e-mail message to with the word ’subscribe’ in the title and body of your message.