Spring is coming, and it appears as if this year’s thaw is unlikely to lead to shoreline flooding and high water levels for the St. Lawrence River and Lake Ontario.
That’s according to Andrew D. Gronewold, University of Michigan professor of environmental science, who has studied the Great Lakes water levels for more than a decade.
Citing the U.S. Army Corps of Engineers, which tracks water levels in major water bodies across the nation, Mr. Gronewold said estimates indicate that Lake Ontario will see its water level increase by about a foot on average through the spring before starting the seasonal decline in early summer.
“The band of uncertainty around that average falls within the range of historical limits,” he said. “That’s important, I know, to the people of Lake Ontario who experienced record highs in 2017 and 2019. According to the current forecasts, it does not look like that water level is expected to reach those extremes this spring.”
Mr. Gronewold said there are a variety of factors that play into a prediction like that. Lake Ontario is a very complicated body of water for which to forecast.
“Lake Ontario is an integrator of what I’ll call hydrological processes across the Great Lakes,” Mr. Gronewold said. “Snow melting across the Lake Superior basin, the Lake Michigan, Lake Huron and Lake Erie basins all aggregates in Lake Ontario.”
Mr. Gronewold said the timing and volume of snow-melting events across the Great Lakes region all impact Lake Ontario because almost all water in the lakes ends up flowing into Lake Ontario through the Niagara River.
Another major factor in the lake and river’s annual water level cycle is the Moses-Saunders Power Dam in Massena. The International Joint Commission, a collaboration to control waterways shared by Canada and the United States, controls the amount of water that leaves the Great Lakes system at that dam under rules set by Plan 2014, and its decisions can have major impacts on Lake Ontario and the St. Lawrence River.
Ultimately, flow controls at the power dam can only raise or lower the lake and river water levels by a few inches at most, but it’s by far the most impactful way to directly address water levels.
“One of the challenges with Plan 2014 is balancing what comes into Lake Ontario with what happens downstream,” he said. “That’s where I would pay particular attention.”
The Ottawa River Basin, which drains into the St. Lawrence River around Montreal, is a major concern for IJC officials in Plan 2014. When the basin has high water, the flow of water from the upper St. Lawrence and Great Lakes has to be restricted to avoid flooding Montreal and other areas beyond the power dam.
“In 2017 and 2019, there was a lot of snow and a lot of melt that came through the Ottawa River, which led to flooding conditions in Montreal and elsewhere downstream,” he said. “That affected how much water could be let out of Lake Ontario through the binational agreements and Plan 2014.”
According to the Ottawa River Regulation Planning Board, Tuesday’s water levels were about average, or slightly below average at nearly every measuring station along the Ottawa River.
Mr. Gronewold cautioned that predicting weather patterns is imprecise, and with a watershed the size of the Great Lakes, things only get more complex.
“Even though we have really good meteorological forecasts and a good understanding of climate systems, it’s hard to forecast those types of continental scale events anything out more than two to three weeks,” he said.
He said meteorologists, hydrologists and others who study weather patterns typically turn to historical patterns to predict long-term conditions, but as climate change worsens and global average temperatures rise, that’s proven less useful.
He said the period between 2014 and 2019 saw the most precipitation fall in recorded history for North America, which some scientists suggest came about due to warming conditions in the Gulf of Mexico and a warmer atmosphere moving more water through the water cycle.
“Recently, we’ve noticed that precipitation has slowed considerably,” he said.
The professor said it’s not known why that has happened, but researchers are working to find answers.
When it comes to the north country, Lake Ontario and the St. Lawrence River, Mr. Gronewold said there are many global factors at play that determine water levels, and there will always be a degree of uncertainty from year to year.
“It’s one of the most complicated hydrologic systems to understand, monitor and forecast for in the world,” he said.