Fairer weather and an overall drop in the amount of water flowing from Lake Erie has allowed Lake Ontario water levels to continue falling at what the international agency overseeing it claims is a faster rate.
Levels have dropped 11.4 inches since June 13, according to the International Joint Commission, which is about when the International Lake Ontario-St. Lawrence River Board first raised outflows from the lake through the Robert Moses-Robert H. Saunders Power Dam in Massena and Cornwall, Ontario, to 10,400 cubic-meters-per-second, the record high for sustained outflows. Outflows have been maintained at 10,400-cubic-meters- per-second, or enough water to fill 34,342 bathtubs per second for 57 consecutive days, which exceeds the 55 days outflows were kept at that level in 2017, the last time Lake Ontario exhibited record-high levels.
According to the commission, water levels had decreased an average of one centimeter each day since Aug. 2 and Lake Ontario levels had fallen to 248.10 feet Thursday, 2.76 inches below the historic maximum for that time, 248.33 feet, but 2.17 feet above the historic average, 245.93 feet. Record-high flows from Lake Erie for this time of year continue to pass into Lake Ontario, and while they have risen slightly since the beginning of the month, they have declined overall since mid-June by about 500-cubic-meters-per-second, enough to fill more than 1,600 average-sized bathtubs per second.
“Nonetheless, Lake Erie has also been declining recently, and this has allowed Lake Ontario’s rate of decline to increase slightly over the last several days,” the commission wrote in a news release. “After some scattered rainfall the past day or so, drier weather is expected to return and continue through the end of the week allowing lake levels to continue to decline.”
Excessive precipitation across the Great Lakes Basin and high outflow from Lake Erie, which also experienced record-breaking water levels, were key factors in Lake Ontario and the upper St. Lawrence River experiencing unprecedented water levels.
The effects were compounded by a heavy snow pack along the Ottawa River basin melting a little later than usual and major rains throughout the basin in late April and into May, which led to record flows from the river into the lower St. Lawrence River. This excess water caused flooding in large areas near Montreal. In order to mitigate the effects of this flooding, the river board had to reduced outflows in the spring, backing water up on Lake Ontario, but it has since been able to raise outflows and keep them at record high sustained levels.
“The (river board) is acutely aware and concerned for the welfare of the many affected shoreline property and business owners, as well as the shoreline environmental damage and other impacts of the continuing high water levels,” the commission wrote.
The board’s current regulation strategy includes deviations from the prescribed flows of Plan 2014 with the specific intention of maximizing the rate of relief that lower water levels will provide to those affected.