Lake Ontario outflows increased to record levels amid favorable conditions

Jan 6, 2020

Now that the shipping season on the St. Lawrence Seaway is at an end and warmer weather has reduced ice buildup on the St. Lawrence River, officials in charge of regulating water levels in Lake Ontario are increasing outflows through the Moses-Saunders Dam. 

"This is a short window, just a temporary opportunity, but it’s a good one for us," said Tony David, a member of the international Lake Ontario-St. Lawrence River Board, which helps manage water levels.

Right now, water levels in Lake Ontario are about 17 inches above the long-term average and nine inches higher than where they were at this same time in 2019. Last summer saw unprecedented water levels and resulting flooding along the shoreline.

But David says while water levels are significantly higher than in the past, it's very early in the season.

"Where we start off the year has no indication of where we will be or where peak will be," He said. "That’s going to depend entirely on future conditions in the system."

One of those conditions is ice formation on the St. Lawrence River. When temperatures drop again, outflows will have to be temporarily reduced to allow for a stable ice cover to form on the river, which helps avoid ice jams that can cause flooding. But once that cover is formed, outflows will be increased again.