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Strange Islands and Hidden Springs Showed Up In Great Salt Lake — Now, The Scientists Know Why

On the bed of the saline lake, Bill and his colleague made a groundbreaking discovery of an underground freshwater reservoir.

BY NEHA B.

PUBLISHED 4 HOURS AGO

(L) Geoscientists investigating salt lake's shores with piezometers (Cover Image Source: Facebook | University of Utah) | (R) The Great Salt Lake in Utah, USA. (Representative Cover Image Source: Getty Images | Nick Pedersen)

The Great Salt Lake is drying. In the past few years, its waters have shrunk to almost half, NPR said. The dwindling waters cause the wet sediment on the shore to dry up. And as it dries, it turns into a carpet of leached dust, silt, and toxic chemicals. Day after day, winds blowing over these shores cough up the toxic chemicals into the attached settlements where humans dwell. Several years ago, Bill Johnson, a geochemist from the University of Utah, visited the lake and noticed the strange bubbling of water and gases on the surface.

The Great Salt Lake nearby Salt Lake City, Utah, USA, North America. (Representative Image Source: Getty Images | Alex Potemkin)

His suspicion exploded into a full-fledged curiosity when he and his fellow scientists observed a trail of mounds on the southeast shores of the lake. In summer this year, they presented a study at the Geochemical Society’s 2025 Goldschmidt conference, revealing that the lakebed carried a mysterious treasure trove of freshwater that could revolutionize the water culture in this region.

Person watching an island from the shore of The Great Salt Lake nearby Salt Lake City, Utah, USA, North America. (Representative Image Source: Getty Images | Kryssia Campos) — Person watching an island from the shore of The Great Salt Lake near Salt Lake City, Utah, USA, North America. (Representative Image Source: Getty Images | Kryssia Campos)

When Johnson had first noticed strange ripples on the surface of the lake, he tossed a gauze into the shallow water, only to be disappointed. It didn’t strike the bottom of the lake. “I always wondered what the heck that was, because it seemed like groundwater was coming to the system at a huge rate,” he said in a press release. Later on, his suspicions grew when some fellow geologists and geoscientists also noticed strange mounds emerging from the lake’s exposed playa, most of them choked with thickets of phragmites, the water-hogging invasive reed cluttering the lakeshore, as they described it.

Hipster wandering on the shores of The Great Salt Lake nearby Salt Lake City, Utah, USA, North America. (Representative Image Source: Getty Images | Alex Potemkin)

Most of the lake’s waters, they believed, came from rainfall and surface runoff. But these mounds and that strange bubbling of water and gases hinted that some water could be contributing from deep within the lakebed. This prompted them to investigate the saline waters and figure out the root cause of the protruding mounds, which probably made a fascinating discovery. They anticipated that something was lurking under the ground. All they needed was some sophisticated instruments.

Man in a desert in Utah near The Great Salt Lake nearby Salt Lake City, Utah, USA, North America. (Representative Image Source: Getty Images | AscentXMedia)

From the entire gear, two particular instruments became their greatest ally: piezometers and aerial electromagnetic surveyors. Together with a graduate student, Ebenzer Adomako-Mensah, Johnson visited the lake last year and mounted several piezometers on the lake’s grounds to record underground water pressures at various depths. Another crucial instrument that offered support in this investigation was a giant circular device that resembled a giant ferry wheel, except that it was suspended by a helicopter instead of being mounted on the ground.

As the pilot flew the copter in a grid pattern over the bay, the device dangling from it collected information about lake deposits lurking under the lake bed via airborne electromagnetic survey. The device was a brainchild of Expert Geophysics, a Canadian firm Johnson had hired in February 2025 for the investigation. Once the information was collected, an extensive analysis began. It revealed a complex picture of an underwater reservoir that was likely lurking on the lakebed. A secret plumbing system materialized on the canvas. Johnson hypothesized that the mounds they noticed were probably the result of the subsurface plumbing system that delivered fresh groundwater under pressure into the lake and its surrounding wetlands.

Aerial view of the Great Salt Lake nearby Salt Lake City, Utah, USA, North America. (Representative Image Source: Getty Images | Shunyu Fan)

“Water in the lake has spent a significant time underground on its way to the lake. But where that happened, we don’t know,” said Johnson. “Did that happen somewhere in the uplands where the water spent time in the ground and emerged in the stream before going to the lake? Or was it transmitted directly to the lake?” The team is not sure where this freshwater originated, such as in the mountains or a snowmelt. All they know is that it could be fresh all the way down. Wherever it originated, Johnson believes that it could prove to be an invaluable resource. “The last thing we wanted to do is for this to be characterized as a water resource we should be tapping,” he said. “It’s much more fragile than that, and we need to understand it better.”

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