Water levels on Lake Ontario are within a half-metre of an all-time record set in 2017 and are expected to continue to rise, says Rob Caldwell.
Caldwell is the Canadian secretary of the International Lake Ontario–St. Lawrence River Board, part of the International Joint Commission, which controls the outflow of the lake through the Moses Saunders Dam between Cornwall, Ont., and Massena, N.Y.
“We’re seeing a continuation of above-average water supply to the entire Great Lake system for the past several years,” says Caldwell.
He says part of the excess supply is believed to be due to climate change.
“The 2017 record was 75.88 metres,” says Caldwell, adding all lakes levels are measured according to how high they are above sea level.
Lake Ontario is the 10th largest lake in the world and increased supply to it and the other Great Lakes is also due to the spring snowmelt and water running down creeks and streams into the Great Lakes.
Rainfall is another factor in the amount of water in the system.
“Rainfall directly on the lake can have an immediate impact. In large watersheds, it can several days to impact.”
For example, he says rain on the upper Ottawa River can take three weeks before it reaches the mouth of the river and St. Lawrence River.