The International Lake Ontario-St. Lawrence River Board will continue to maximize St. Lawrence River outflows, including from the Moses-Saunders dam in Massena.

Record-breaking natural conditions have exceeded the capability of water level regulation to prevent the wide-spread flooding and coastal impacts experienced across the Lake Ontario – St. Lawrence River basin. Gradually decreasing inflows from Lake Erie, drier weather and record-setting outflows on the St. Lawrence River have resulted in a steadily declining Lake Ontario, down 45 cm (17.7 in.) below the peak. The Board will continue to prescribe the most aggressive outflows with the goal of reducing Lake Ontario as quickly and safely as possible, according to a statement from the board

The board met on Aug. 15 to assess current conditions and hydrologic forecasts, and review the ongoing impacts of high water levels and flows throughout the Lake Ontario – St. Lawrence River system. Outflows will continue at 9910 m³/s (350,000 cfs) until midnight Aug. 18, when they will be lowered slightly to 9870 m3/s (348,600 cfs), which will remain the highest flow ever recorded at this time of year. High outflows remain necessary to provide relief to those affected by this year’s high water levels on Lake Ontario, but the decrease is necessary to balance the impacts to navigation and other interests in the St. Lawrence River, according to a news release from the board.

Ottawa River flows into the St. Lawrence River have decreased and, while levels of Lake St. Louis (near Montreal) continue near record highs for this time of year, they are now below flood levels. However, the unprecedented outflow from the Moses-Saunders Dam has resulted in the lowest water levels experienced on Lake St. Lawrence (near Cornwall, Ontario and Massena) since 1998. Falling water levels will result in increased currents and potentially hazardous navigation conditions for all in the international section of the St. Lawrence River, the board said.

Water levels are expected to continue to decline rapidly into the fall throughout the system. The board says they, in conjunction with staff, continue to monitor and reassess conditions on an ongoing basis.