What's New
Lake Superior, the largest freshwater lake in the United States and a critical natural resource, experienced its lowest water levels in a decade in 2024.
According to the National Oceanic and Atmospheric Administration (NOAA), the lake's level at Grand Marais in Minnesota was 601.5 feet at the start of November, more than half a foot lower than at the same time in 2023.
That might not sound like much, but given the lake's 31,800 square mile footprint, the difference marks a significant drop—the equivalent of losing the same volume as more than five million Olympic swimming pools.
Water levels fluctuated throughout the year, hitting a low of 601.0 feet in March and peaking at 602.3 feet in July.
Why It Matters
These shifts highlight significant hydrological challenges for Lake Superior, which holds 10 percent of the world's fresh water.
Lake Superior is part of the Great Lakes system, which provides drinking water, supports ecosystems and drives economic activity across the U.S. and Canada.
Changes in its water levels can have profound consequences. Lower levels can reduce the lake's shipping capacity, forcing vessels to carry lighter loads, which increases costs.
Altered water levels and temperatures can also disrupt ecosystems, harming native species while benefiting invasive ones like zebra mussels.
Changing conditions can also "encourage the growth of certain waterborne bacteria that can make people ill," according to the U.S. Environmental Protection Agency.
Moreover, the observed decline aligns with broader climate trends affecting the Great Lakes. Warmer temperatures, reduced ice cover and increased evaporation exacerbate water loss, while shifting precipitation patterns further contribute to variability.
What to Know
Drought was a defining factor in Lake Superior's 2024 water levels. Despite intense storms and lake-effect snow in recent weeks, much of the Midwest and Northeast remained abnormally dry, with 40 percent of the Midwest still in drought as of December, according to the U.S. Drought Monitor.
Lake Superior is currently six inches below its long-term December average, with further declines expected in the coming months, according to the U.S. Army Corps of Engineers.
Historical data reveals that water levels on the Great Lakes, including Lake Superior, have oscillated dramatically in recent decades.
High water levels and flooding defined the period from 2014 onward, following a prolonged low-level phase from 1998 to 2014.
Scientists attribute these fluctuations to complex interactions between precipitation, evaporation, ice cover and runoff.
What's Next?
Looking ahead, the future of Lake Superior's water levels remains uncertain. Climate models suggest that variability—marked by extreme swings between high and low levels—may become the norm.
"Planning for multiple plausible futures, including extremes, can increase the robustness of management practices and preparedness for climate change impacts," the Great Lakes Integrated Sciences and Assessments said in its Lake Levels Overview.
The U.S. Army Corps of Engineers said it expects Lake Superior's still-water surface elevations—which measure water levels across the entire lake surface rather than at a specific point—to fall by three inches in the next month.
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