MASSENA — Residents on Lake St. Lawrence should look out for swings between extreme high and low water levels this winter due to high Lake Ontario levels and variations in outflow management.
The lake typically rises when the International Lake Ontario-St. Lawrence River Board, which manges outflows from Lake Ontario, reduces them to form a stable ice cover near the Robert Moses-Robert H. Saunders Power Dam in Massena and Cornwall, Ontario. Forming the ice cover helps prevent ice jams.
Lake Ontario, which is connected to Lake St. Lawrence via the St. Lawrence River, remains about two feet above its historic average as of Sunday, and is expected to stay high for weeks, if not months, to come. With more water in Lake Ontario and outflow reductions needed to form the stable ice cover, Lake St. Lawrence could experience even higher than normal water levels, according to an announcement from the International Joint Commission, which oversees the river board.
The board cannot determine a specific time line for ice formation as it depends on water and air temperatures.
On the other hand, the river board has been seeking more opportunities to increase outflows whenever possible to help lower Lake Ontario water levels. Raising outflows can lower Lake St. Lawrence water levels. The board particularly hopes to release more water through the dam after it forms a stable ice cover, when it can typically raise outflows without fear of ice jams. The commission expects Lake St. Lawrence levels to decrease beyond normal as the board attempts to further release water from Lake Ontario.
The commission extended the board’s ability to deviate from its outflow management regulations in Plan 2014 until June 2020, which would allow the board to release more water through the dam at times the plan typically may not allow. The river board will implement a winter outflow deviation strategy.
The board, however, must ensure allowing more water through the dam would not harm safe shipping conditions, communities on Lake St. Lawrence and their water intakes and downstream communities like Montreal, while allowing an ice cover to form.
High lake and St. Lawrence River water levels resulted in flooded homes, submerged docks and inundated and eroded shorelines in waterfront communities this year. Some fear the waters will wreak similar havoc next year as levels remain above normal, and predictions from the U.S. Army Corps of Engineers indicate they will most likely remain above normal for months to come.