The Great Lakes are not drying up. Despite alarming headlines during a stretch of below-average water levels in the early 2000s, the system has rebounded dramatically and, in several cases, set records for high water. The real story is more interesting and more unsettling than a simple vanishing act: the Great Lakes are swinging between extremes, with periods of historic lows followed by record highs within the span of a single decade. Understanding why those swings happen, what actually threatens the lakes, and what climate change means for their future paints a far more nuanced picture than the “drying up” narrative suggests.
The Low-Water Scare and the Rebound That Followed
From roughly 1998 through 2012, Lakes Superior and Michigan-Huron experienced a persistent stretch of below-average water levels that included several months of record lows. For communities and industries that depend on the lakes, this felt like a slow-motion crisis. Shipping companies were forced to lighten cargo loads because lower water levels mean shallower harbors and channels, and a vessel that runs too deep risks scraping bottom. Beaches grew wider, exposed lake beds hardened in the sun, and docks stood high above the waterline. It was easy, during those years, to imagine the lakes slowly emptying.
Then the trend reversed sharply. Between January 2013 and December 2014, water levels on Lake Superior and Lake Michigan-Huron rose at the highest rate ever recorded for a two-year period, ending the 15-year slump.1Water Resources Research. Hydrological drivers of record‐setting water level rise on Earth’s largest lake system By the late 2010s, Lake Michigan had reached record highs, flooding shoreline properties and chewing away at coastal bluffs. The lakes had not simply recovered; they had overcorrected. This whiplash pattern is the defining feature of recent Great Lakes hydrology, not a one-way decline.
What Drives These Wild Swings
Great Lakes water levels are set by a water budget: precipitation falling directly on the lake surface and across the surrounding watershed, runoff from rivers and streams, groundwater seeping in from below, and evaporation pulling water back into the atmosphere. Small shifts in any of these inputs or outputs, sustained over months or years, can move lake levels significantly because the lakes are so vast that even a thin layer of water across their surface represents an enormous volume.
During the low-water years, a common explanation pointed to reduced winter ice cover. The reasoning was intuitive: warmer winters mean less ice, which means more open water exposed to cold, dry air, which means more evaporation. But recent research has complicated this picture considerably. A 2025 study found that ice cover does not have a strong relationship with lake evaporation in winter months and that the magnitude of the ice effect on moisture-flux reduction often falls within the range of natural variability. Instead, the seasonal atmospheric conditions over the lakes, including wind speed, humidity, and temperature differences between the water surface and the air, appear to matter more than whether ice is physically present.2Water Resources Research. Does Ice Cover Cap Evaporation in Large Lakes? This matters because it means the old story of “less ice equals lakes drying up” was too simple. The atmosphere’s behavior over the lakes is a bigger lever than the presence or absence of an ice lid.
Precipitation, meanwhile, is the dominant input. The wet years that started in 2013 brought above-average rainfall and snowmelt to the basin, and those were the primary drivers of the record-setting water level rise.1Water Resources Research. Hydrological drivers of record‐setting water level rise on Earth’s largest lake system When the climate delivers a few consecutive years of heavy precipitation, the lakes fill. When it delivers dry stretches, they drop. The system is responsive enough to shift from record lows to record highs in less than a decade.
Human Actions That Actually Did Lower the Lakes
While weather and climate drive the dramatic swings, human engineering has made permanent, measurable changes to Great Lakes water levels. The most significant was the dredging and widening of the St. Clair River, the channel that connects Lake Huron to Lake St. Clair and eventually Lake Erie. Over the course of the twentieth century, navigation improvements to this river effectively increased its flow capacity, allowing water to drain out of Lake Michigan-Huron faster than it naturally would. One analysis estimated this dredging permanently lowered Lake Michigan-Huron by about 0.27 meters, representing roughly 32 cubic kilometers of lost freshwater.3Journal of Great Lakes Research. Effect of Channel Changes in the St. Clair River During the Present Century A separate study confirmed a lowering of about 0.18 meters due to channel dredging in the upper river, a number in the same ballpark though slightly more conservative.4Journal of Great Lakes Research. Pre-1900 St. Clair River Flow Regime
A foot of permanent lowering across lakes that large is a meaningful shift. It does not cause the lakes to “dry up,” but it does mean that every low-water period starts from a lower baseline than it would have otherwise. During the worst of the early-2000s slump, that extra deficit contributed to the sense of emergency.
The Chicago Diversion is another human alteration worth knowing about. In 1886, Chicago decided to build a 45-kilometer canal to divert lake water and flush the city’s diluted sewage into the Illinois River system, reversing the flow of the Chicago River away from Lake Michigan.5Journal of Great Lakes Research. History of the Chicago Diversion and Future Implications The diversion still operates today, though at a flow rate governed by a Supreme Court decree. Its effect on lake levels is modest compared to the St. Clair River changes, but it remains a politically sensitive topic, especially for downstream states and Canadian provinces that view the Great Lakes as a shared resource.
The Damage High Water Does
Ironically, the bigger problem in recent years has not been too little water but too much. When Lake Michigan rose to record highs during the 2010s, some coastal sites experienced habitat loss rates an order of magnitude higher than during previous high-water periods throughout the twentieth century.6Journal of Great Lakes Research. Rapid water level rise drives unprecedented coastal habitat loss along the Great Lakes of North America Beaches and dunes that had built up during the low-water years were suddenly submerged. Bluffs that had seemed stable for decades began collapsing into the lake.
The speed of the transition matters as much as the absolute water level. The research suggests that rapid and relatively large changes from low water to high water are the main driver of severe erosional losses, because the coastal system cannot adjust when it shifts abruptly from one regime to another.6Journal of Great Lakes Research. Rapid water level rise drives unprecedented coastal habitat loss along the Great Lakes of North America A gradual rise gives vegetation and sediment time to adapt. A sudden one overwhelms shoreline defenses. This has real consequences for homeowners, municipalities, and infrastructure. High-risk erosion areas along the Great Lakes are defined as locations where the shoreline has been retreating at a rate of at least 30 centimeters annually over a 15-year period, and climatic factors like rising water levels and increased storm intensity accelerate that process.7ScienceDirect / Journal of Great Lakes Research. Improving geospatial coastal vulnerability indices for the Great Lakes
So the question for many lakeside communities has flipped: instead of worrying about the lakes shrinking, they are dealing with the aftermath of the lakes expanding. Roads, sewage systems, and waterfront parks that were designed for one water-level regime are now being pounded by a different one.
How Low Water Hurts Shipping and the Economy
When the pendulum does swing back toward low water, the economic consequences arrive quickly. Cargo ships on the Great Lakes load to a specific draft, the distance between the waterline and the bottom of the hull. Lower water levels mean shallower channels, which means ships must carry lighter loads to avoid running aground.8Water Resources Research. Hedging the financial risk from water scarcity for Great Lakes shipping For the massive freighters that carry iron ore, coal, and grain, even a few inches of lost draft translates to thousands of tons of cargo left on the dock per trip. Over a shipping season, those losses add up to millions of dollars in extra transportation costs, which ripple through steel production, power generation, and agricultural exports.
During the early-2000s lows, some harbors became difficult to navigate at all. Marinas had to be dredged, boat launches sat above the waterline, and ferry services were disrupted. The shipping industry has long understood that water levels are variable, but the speed and magnitude of recent fluctuations make planning harder. A company building a fleet of vessels today has to ask whether to design for the record lows of 2012 or the record highs of 2020, and the honest answer is both.
The Ground Beneath the Lakes Is Still Sinking
One factor in Great Lakes water levels that most people never consider is that the land itself is moving. When the Laurentide ice sheet covered the region during the last glaciation, its enormous weight pressed the Earth’s crust downward. When the ice melted, the crust began slowly rebounding upward, a process called glacial isostatic adjustment that is still happening thousands of years later. But the rebound is uneven. Areas that were directly under the thickest ice are rising, while areas at the periphery of the former ice sheet are actually sinking as the Earth’s mantle flows back toward the rebounding center.
GPS measurements show that Wisconsin and Michigan are subsiding at roughly 1 to 4 millimeters per year, driven primarily by the viscous collapse of the former ice sheet’s forebulge and secondarily by the elastic loading of the lake water itself pressing down on the crust.9Journal of Geophysical Research: Solid Earth. Rise of Great Lakes Surface Water, Sinking of the Upper Midwest of the United States, and Viscous Collapse of the Forebulge of the Former Laurentide Ice Sheet A few millimeters per year sounds trivial, but over decades and centuries it adds up. Models of this process have historically focused on the ice sheet load alone, but where the topography is low-relief, the weight of the lake water itself also contributes meaningfully to the deformation.10Journal of Great Lakes Research. Effects of Great Lakes Water Loading upon Glacial Isostatic Adjustment and Lake History
For water levels, this means the basin geometry is slowly changing. Some shorelines are being tilted relative to others, which can make water levels appear to rise at one end of a lake and fall at the other, even if the total volume of water stays the same. This is a geological process operating on timescales much longer than climate variability, but it forms the backdrop against which all the shorter-term fluctuations play out.
What Lies Beneath the Surface
People tend to think of the Great Lakes as giant pools of surface water, but they are connected to an immense groundwater system. Aquifers on the U.S. side of the Great Lakes Basin store roughly 4,100 cubic kilometers of water, a volume comparable to the entire contents of Lake Huron. Groundwater contributes to the lakes through both direct discharge into the lake bed (about 2.7% of input) and indirect discharge via streams and rivers (about 42%).11ScienceDirect (Journal of Great Lakes Research). Impacts of climate change on groundwater in the Great Lakes Basin: A review
That indirect contribution is surprisingly large. Nearly half of the water flowing into the Great Lakes through tributaries started as groundwater that seeped into those streams upstream. This means that anything affecting groundwater recharge, including changes in precipitation patterns, land use, and pumping for agriculture or municipal supply, indirectly affects the lakes themselves. Climate change projections for the basin include shifts in the timing and intensity of precipitation, which could alter how much water infiltrates the ground versus running off the surface quickly. The groundwater connection is one more reason the “drying up” question is not as simple as looking at the lake surface.
How the Great Lakes Compare Globally
If you want to know which major water bodies are genuinely drying up, the Great Lakes are not on the list. A global analysis of lake and reservoir volumes found that the Great Lakes showed average volume increases during the study period, while considerable reductions in water storage were observed in the western United States, with major declines in Lake Mead, Lake Powell, and the Great Salt Lake.12Copernicus Publications. A global lake and reservoir volume analysis using a surface water dataset and satellite altimetry The Great Salt Lake, the Aral Sea, and Lake Chad are examples of water bodies experiencing long-term, structural decline driven by a combination of diversion, irrigation withdrawal, and climate shifts. The Great Lakes face serious challenges, but their fundamental water budget remains intact in a way that these other systems’ budgets do not.
Part of the reason is sheer scale. The Great Lakes hold about 21% of the world’s surface fresh water. Their basin receives enough precipitation and runoff to sustain them even as evaporation and outflow remove enormous quantities every year. The system is big enough to buffer against the kinds of human withdrawals that have devastated smaller lakes, particularly because the Great Lakes Compact, signed into law in 2008, tightly restricts new diversions of water out of the basin.
Warming Water and Shifting Seasons
Climate change is not going to dry up the Great Lakes, but it is reshaping how the system behaves. Over the last several decades, the region has experienced a significant rise in temperatures. Lake Superior’s extraordinary summer warming event in 1998 illustrated how sensitive the lake can be to increasingly warmer atmospheric conditions. Research found that unusual warming events can result from two factors: anomalously high summer air temperatures and increased strength of stratification resulting from a warm spring.13Water Resources Research. The role of stratification on lakes’ thermal response: The case of Lake Superior
Stratification is the layering of water by temperature, with warm water sitting on top and cold water at the bottom. When spring is warmer than usual, this layering sets up earlier and more strongly, which concentrates summer heat in a thinner surface layer. The result is surface temperatures that spike well above historical norms. Warmer surface water can increase evaporation rates during fall and early winter, when the still-warm lake meets cold, dry air masses. It also affects every organism in the lake, from the algae at the base of the food web to the cold-water fish species that many communities depend on.
What Climate Models Say About the Future
If the Great Lakes are not drying up now, could they dry up in the future? Climate projections for the basin are genuinely uncertain, which is both reassuring and unsettling. A study modeling future Great Lakes water levels under climate change found that the individual downscaling cases highlight the uncertainty in climate projection, showing both increases and decreases in annual water supply and water-level projections depending on which climate model and scenario is used.14Journal of Hydrology. Future rise of the Great Lakes water levels under climate change Some scenarios project modestly higher average levels, others modestly lower. What many of them agree on is that variability will increase: the swings between high and low will get wider, and the transitions between them may get faster.
This is arguably worse than a slow, predictable decline, which at least allows for planning. A system that lurches between extremes stresses infrastructure from both directions. Seawalls and flood barriers built for high water sit useless during low-water years. Harbor-dredging investments made during low-water emergencies become irrelevant when levels surge back up. Communities and governments have to prepare for both extremes simultaneously, which is expensive and politically difficult.
Wildlife Caught in the Whiplash
The ecological effects of these fluctuations extend well beyond shoreline erosion. Coastal wetlands along the Great Lakes are among the most productive habitats in the region, supporting marsh birds, fish spawning, and amphibian populations. But these wetlands are squeezed by a combination of water-level swings and invasive species. Research in Saginaw Bay found that the expansion of invasive Phragmites, a tall reed that forms dense monocultures, reduced habitat connectivity by 12 to 14 percent and cut carrying capacity for marsh bird species by 19 to 39 percent between the early 2000s and 2010.15Waterbirds. Ecologically Scaled Responses of Marsh Birds to Invasive Phragmites Expansion and Water-Level Fluctuations Interestingly, as water levels began rising after 2010, Phragmites coverage declined and carrying capacity recovered slightly, by 4 to 10 percent. High water drowns out the invasive reed, offering native marsh plants a window to reclaim territory.
This creates a peculiar dynamic where the same water-level rise that erodes beaches and damages homes can actually benefit certain wetland ecosystems. It is a reminder that “good” and “bad” water levels depend entirely on which part of the system you are looking at. A level that devastates a beachfront subdivision may be exactly what a coastal marsh needs.
Watching the Lakes From Space
One reason scientists can track Great Lakes water levels with so much confidence today is advances in satellite monitoring. Spaceborne laser altimetry missions have achieved remarkable precision in measuring inland water surfaces. The ICESat-2 satellite, for example, provides lake water level retrievals with an accuracy of about 6 centimeters, a level of precision that was impossible from orbit just a couple of decades ago.16Journal of Hydrology. Inland water level measurement from spaceborne laser altimetry: Validation and comparison of three missions over the Great Lakes and lower Mississippi River Combined with traditional gauge networks and hydrological models, these satellite platforms mean the Great Lakes are among the most intensively monitored water bodies on Earth. If a genuine long-term decline were underway, the data would catch it early and unambiguously. So far, the data show fluctuation, not depletion.