Lake Huron reaches one of lowest levels since 1918
LAKE HURON—For the first time in over a decade, all five Great Lakes have slipped below their average water levels — a quiet but consequential marker in the escalating story of climate change. As of March 2025, Lakes Superior, Michigan-Huron, St. Clair, Erie and Ontario all began the month below their historic averages, a rarity not seen since February 2013.
The data, released last week in LEVELnews by Environment and Climate Change Canada, paints a stark portrait of shifting hydrological patterns: drier basins, unusual declines and water levels now flirting with lows last observed in the early 2010s. Lake Superior and Lake Ontario posted their lowest February levels since 2013; lakes Michigan-Huron dropped to a level not seen since 2014.
Historically, late winter is the time of year when most of the lakes begin their seasonal rise—but not this time. Instead, Lakes Michigan-Huron suffered its fifth largest February decline on record (1918). Lakes St. Clair, Erie and Ontario also bucked the trend, registering declines instead of expected increases.
Behind the scenes, a trifecta of forces—low precipitation, reduced runoff and higher evaporation rates—are rewriting the old playbook of Great Lakes behaviour. Lake Superior saw just 90 percent of its typical February precipitation. Lakes Michigan-Huron came in at a paltry 62 percent. Net basin supplies—a measure of all water entering and leaving each lake—were classified as “very dry” for Lakes Superior and Michigan-Huron, and simply “dry” for Lakes Erie and Ontario.
The lakes are no strangers to fluctuation—natural cycles of high and low levels have been documented for centuries. But the choreography is changing. Warmer winters mean more evaporation as ice cover diminishes. Heavier rainfall comes in bursts, followed by extended dry spells. And when ice does form, as it did more extensively this winter compared to recent years, the underlying supply chain of water remains fractured.
Low lake levels aren’t just an abstract metric. They ripple out to communities like Manitoulin, where shipping, fisheries, tourism and shoreline ecosystems are all sensitive to such shifts. Lower levels can expose more shoreline, increasing erosion risk when powerful winter storms sweep through. Marinas and shipping channels could require costly dredging, and coastal wetlands—vital nurseries for fish and birds—shrink.
Lake Superior, notably, began March a full 12 cm below chart datum, the reference point for safe navigation. While the other lakes hovered above their respective datum levels, the margin is thinning.
Forecasts suggest that only an exceptionally wet spring and summer could push levels back to average on Lakes Superior or Michigan-Huron. Lake Ontario might see an uptick if precipitation stays strong, but under most scenarios, the lakes are expected to remain low through the next six months.
