Flooding in Canada slows relief upstream along the St. Lawrence and Lake Ontario

May 2, 2019

Major flooding in Canada is still slowing efforts to relieve high water in Lake Ontario through the St. Lawrence River.

Lake Ontario is higher than average and expected to keep rising.

Sandbags lined up for flood protection in Lachute, Quebec, just upstream from Montreal on the Ottawa River.
Credit James Morgan

The International Lake Ontario – St. Lawrence River Board is controlling the amount of water it lets through the Moses Saunders dam at Massena – balancing the high lake waters with flooding downstream at Montreal, where the Ottawa River is contributing to a state of emergency.

Board member Tony David says as long as flows from Ottawa River remain high, release of water through the Moses – Saunders dam near Massena will continue to be restricted.

According to David, “Those constraints to outflows from Lake Ontario - looks that they will continue to apply in the coming days.”

David says water levels in the lake are still significantly lower than two years ago, when there was major flooding.

But that’s likely to change in the coming days.

David said, “Given the situation with the reductions in outflow, we are actually expected to get caught up to where we were in 2017 fairly quickly to where in the next seven to 10 days.”

David said the international board can try to influence high water in Lake Ontario, but it can’t control the lake’s level. It can only manage outflows based on conditions in the St. Lawrence River.