- Freshwater reservoir beneath Utah's Great Salt Lake spans about 3-4 km deep
- Researchers used airborne electromagnetic surveys to map freshwater under lake
- Freshwater saturates sediments beneath hypersaline lake to depths of 10,000 feet
Researchers have discovered a massive freshwater reservoir that could fill approximately 500,000 football fields beneath the Great Salt Lake in Utah. The hidden reservoir, located 3-4 kilometres deep, is a surprising find given the lake's hypersaline surface. Researchers from the University of Utah used airborne electromagnetic (AEM) surveys to map the subsurface and distinguished freshwater from saltwater based on electrical resistivity.
With the help of this innovative approach, the researchers were able to create a detailed 3D image of the lake's geological and hydrological framework.
According to the results published in the Nature-affiliated journal Scientific Reports, the freshwater saturated the sediments beneath the lake's hypersaline surface to depths of 3 to 4 kilometres, which is about 10,000 to 13,000 feet.
"We were able to answer the question of how deep is this potential reservoir, and what is its spatial extent beneath the eastern lake margin. If you know how deep, you know how wide, you know the porous space, you can calculate the potential freshwater volume," said lead author Michael Zhdanov, who is a professor of geology & geophysics and director of the Consortium for Electromagnetic Modeling and Inversion, or CEMI.
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Bill Johnson, who is a hydrologist and also a co-author on all the Great Salt Lake groundwater papers, suggests that freshwater is entering the subsurface toward the lake's interior, not its periphery.
"The unexpected part of this wasn't the salt lens that we see near the surface across the playa. It's that the freshwater underneath it extends so far in towards the interior of the lake and possibly under the entire lake. We don't know," Johnson said on a recent appearance on KPCW's Cool Science Radio show.
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"What we would normally expect as hydrologists is that the brine would occupy the entire volume underneath that lake. It's denser than the freshwater. You'd expect the freshwater from the mountains to come in somewhere at the periphery. But we find it's coming in towards the interior. And there's what appears to be deep volume of this freshwater coming in underneath that saline lens."
The discovery has significant implications for water management, particularly in reducing dust pollution. By harnessing this groundwater, it may be possible to wet the exposed lakebed without disrupting the freshwater system.
