Regulators of Lake Ontario and the St. Lawrence River said Thursday that they will continue to store water on the lake for future need.
The International St. Lawrence River Board of Control said its regulation plan is responding to below-average levels by prescribing outflows that are well below average for this time of year. As a result, since the Ottawa River freshet that began in mid-April, conditions downstream have permitted only a limited amount of additional water to be stored on the lake. The board can store water by reducing outflows through the Moses-Saunders Power Dam at Massena.
The board said that Lake Ontario now is slightly above its plan-specified level, but below its long-term average, as are the other Great Lakes. The under-discharges began when the level on Lake Saint-Louis at Pointe-Claire, Quebec, reached 71.5 feet, about a foot below its flood-alert level.
The board said it will stop storing water if the level at Pointe-Claire reaches 69.55 feet in an attempt to store up to 2 inches of water on Lake Ontario. The board will store more than 2 inches only if the level of Lake Saint-Louis is at risk of exceeding its flood-alert level of 72.5 feet.
The board said its strategy will allow it to address uncertainty of the inflows during the freshet period. Also, while the strategy will provide environmental and recreational benefits from the higher levels on Lake Ontario, the extra water stored can be released later in the season to benefit commercial navigation and recreational boaters on the lower St. Lawrence River.