Is There Freshwater Hidden Beneath the Great Salt Lake?

The Surprising Discovery Under the Brine

Yes — scientists have confirmed a previously unmapped freshwater groundwater system sitting beneath and alongside the brine of the Great Salt Lake in Utah, discovered using airborne electromagnetic surveys flown by helicopter across the lakebed.

The finding overturned a long-held assumption that one of the saltiest lakes in the Western Hemisphere sat atop nothing but more saltwater. Fresh water, it turns out, had been hiding there all along — undetected, uncounted, and unknown to water managers trying to navigate one of the worst droughts in over a millennium.

How Scientists Found It

Researchers flew helicopters towing electromagnetic sensor arrays low over the lakebed. The technology works by measuring how electrical signals travel through different materials underground. Fresh water and brine conduct electricity very differently, which allowed scientists to essentially map what was below the surface without drilling a single well.

What they revealed was a substantial freshwater system threaded beneath the lakebed sediments — sitting quietly under one of the most iconic salt lakes on Earth. The survey produced the first detailed picture of where fresh water and brine coexist in the subsurface geology of the Great Salt Lake basin.

Why the Lake’s Decline Makes This Urgent

The Great Salt Lake has been shrinking for decades, but 2022 marked a grim milestone: the lake dropped to its lowest recorded level since measurements began in 1847. At that point, roughly 800 square miles of lakebed had been exposed — ancient sediment that had sat underwater for generations suddenly open to the air.

That exposed lakebed is not just dry dirt. It contains arsenic and mercury accumulated over centuries of natural and industrial processes. When wind moves across the dry flats, it picks up that toxic dust and carries it directly into the Salt Lake Valley, where approximately 2.5 million people live. The public health implications are significant and ongoing.

A Hidden Water Resource in a Megadrought

The region is currently enduring the driest 22-year stretch in at least 1,200 years — a megadrought that has stressed water supplies across the American West. In that context, an uncounted freshwater resource beneath the lakebed is more than a scientific curiosity. It could represent a meaningful addition to the region’s water accounting.

Water managers have spent years calculating what is available, what is being used, and what might run out. If a significant freshwater system exists beneath the Great Salt Lake that was never factored into those calculations, it raises immediate questions: How large is it? Where does it come from? Can it be accessed sustainably? Could protecting the lake’s water level help preserve this underground system as well?

What This Means for the Future

The discovery does not solve the Great Salt Lake crisis on its own. The lake is shrinking because of a combination of factors — prolonged drought, agricultural water diversion, and rising temperatures — and a subsurface aquifer cannot simply replace the lake’s surface water. But it adds a new layer of complexity to how scientists and policymakers understand the basin.

It also illustrates how much remains unknown about water systems in the American West, even in places that have been studied for over a century. Airborne electromagnetic surveying is now revealing hidden groundwater systems in other parts of the world, suggesting that more surprises like this one may be waiting beneath other lakes, deserts, and coastlines.

The Great Salt Lake has been called a dying lake. Beneath it, fresh water has been quietly waiting to be found.