Water levels will continue to fluctuate over the winter

Residents along Lake Ontario and the St. Lawrence River take warning, the International Lake Ontario – St. Lawrence River Board says to expect both high and low water levels this winter.

The Board says they will implement a winter deviation strategy as Lake Ontario remains above average for this time of the year.

High water levels are anticipated when ice begins forming at critical areas of the St. Lawrence River.  When ice begins to form, outflows through Moses-Saunders Dam need to be reduced to help create a stable ice cover on the river.

The Board says flow management during ice formation helps to prevent ice jams in the St. Lawrence River that can restrict flows and cause local flooding.

The reduced outflows cause levels of Lake St. Lawrence, immediately upstream of the dam, to rise temporarily.  The  effects are reduced moving upstream and tend to be negligible beyond Iroquois, ON and Lisbon, NY.

With Lake Ontario expected to remain well above average for at least the next several weeks, this will also contribute to higher levels of Lake St. Lawrence this winter.

The Board is therefore advising residents of Lake St. Lawrence to prepare for the potential of unusually high levels this winter.

As ice formation is completed, outflows can normally be safely increased under the ice.

This causes Lake St. Lawrence levels to drop, and this drop is also expected to be greater than normal this winter, as the Board continues to investigate potential opportunities to deviate from Plan 2014 and release higher outflows over the next several months in an attempt to lower the risk of high Lake Ontario levels next spring.

At present, the timing of ice formation remains uncertain, as it depends on both water and air temperatures.