Moses-Saunders Dam

Boat haulout assistance planned for Lake St. Lawrence


The Board will temporarily decrease outflows over the second weekend of October to raise Lake St. Lawrence levels significantly and provide a brief, final opportunity for residents of Lake St. Lawrence to remove their boats and other equipment prior to winter.

Last week, the Board agreed to let Lake St. Lawrence levels slowly decline following the 7 September long weekend. Lake Ontario water levels remain above their long-term average value for this time of year. Regulated outflows from Lake Ontario, as prescribed by Plan 2014, will remain high in response to persistent, high supplies into the lake, specifically from Lake Erie.

The high outflows continue to reduce the risk of Lake Ontario flooding in 2021, but have impacted levels in the upper St. Lawrence River, particularly on Lake St. Lawrence, where water levels remain well below average due to its location immediately upstream of the Moses-Saunders dam.

The Board will temporarily reduce outflows through the Moses-Saunders Dam from 9 October through 11 October to raise water levels on Lake St. Lawrence and provide a final opportunity to assist with end-of-season boat haulouts. Decreasing the outflow through the dam causes water levels immediately upstream on Lake St. Lawrence to rise (while increasing the outflow lowers upstream water levels).

This flow decrease will temporarily raise Lake St. Lawrence levels, which will assist marinas, yacht clubs and other recreational boaters in the area in removal of their boats prior to winter. The Board acknowledges the concerns identified by residents in the area, and the Board takes every concern very seriously. The exact amounts of the water level rises will vary depending on a number of factors, including location, wind speed and direction, and other secondary factors. Areas immediately upstream of Moses-Saunders will see the greatest increase, with levels expected to rise up to 30 cm (1 foot) higher than current levels. These effects will be gradually reduced moving further upstream and will be minimal beyond Prescott/Ogdensburg.

Lake Ontario is still lower than it otherwise would be owing to deviations from Plan 2014 that occurred for several months starting in summer of 2019. The relatively brief outflow reduction scheduled for October will restore up to roughly 3 cm (approximately 1.2-inch) of the water that was previously removed. With Plan 2014 continuing to prescribe high outflows, the Board anticipates that this temporary further decrease in outflow will not significantly impact the steady decline of Lake Ontario water levels.

Lake St. Louis’ levels have generally declined since early May. The current level is 21.42 m (70.28 ft), which is 24 cm (9.4 in.) above average. The temporary flow decreases may cause levels on Lake St. Louis to decline by up to approximately 40 cm (16 in.), but they are expected to remain near average.

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             

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 75.92 m (249.1 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.