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Study Reveals Vast Freshwater Reservoir Beneath Great Salt Lake
· Confirmed
In Short: University of Utah researchers have uncovered a vast underground reservoir of freshwater beneath the Great Salt Lake, according to a new study published in Attheu.
The study, which used airborne electromagnetic (AEM) surveys to X-ray geologic structures under Farmington Bay and Antelope Island, found that freshwater saturates the sediments beneath the lake’s hypersaline surface to depths of 3 to 4 kilometers, or about 10,000 to 13,000 feet.
Lead author Michael Zhdanov explained that the helicopter-borne geophysical survey was conducted last year after U scientists documented freshwater welling up under pressure at several spots on the lake’s exposed playa in Farmington Bay, manifesting as strange phragmites-choked mounds.
Researchers from the US analyzed a 120-meter (394-foot) sediment core taken from the lake bed, dating its layers by the radioactive decay of the minerals it carried.
The unexpected part of this discovery was the extent of the freshwater reservoir, which extends far into the interior of the lake and possibly under the entire lake.
Suspicions of the subterranean freshwater reservoir first arose with the sudden appearance of strange reed-covered islands, each 50 to 100 meters (164 to 328 feet) in diameter, in the dried-out lakebed.
The Great Salt Lake has dropped by about 22 feet (6.7 meters) since 1986, driven by drought, climate conditions, and water use, exposing 800 square miles of lake playa, which is now becoming a major source of dust pollution blowing into Utah’s population centers.
Bill Johnson, a UT hydrologist and coauthor of the study, called the findings 'unexpected.' He noted that the freshwater could potentially be used to wet dust hotspots and douse them in a meaningful way without perturbing the freshwater system too much.
The study demonstrated for the first time the ability of AEM methods to detect freshwater underneath the thin layer of conductive salt water at the surface of the Great Salt Lake.
Flat, step-like ledges cut into the mountains around the Great Salt Lake show where Lake Bonneville and Little Valley used to be, and suggest they were both around 300 meters deep.
For most of the past 240,000 years, the lake stayed about the same size but briefly grew 10 times larger on two separate occasions.
The data showed a continuous freshwater reservoir layer stretching from about 330 feet (100 meters) down to 2.5 miles (4 kilometers).
What this adds
Researchers from the US analyzed a 120-meter (394-foot) sediment core taken from the lake bed, dating its layers by the radioactive decay of the minerals it carried.
Suspicions of the subterranean freshwater reservoir first arose with the sudden appearance of strange reed-covered islands, each 50 to 100 meters (164 to 328 feet) in diameter, in the dried-out lakebed.
Flat, step-like ledges cut into the mountains around the Great Salt Lake show where Lake Bonneville and Little Valley used to be, and suggest they were both around 300 meters deep.
For most of the past 240,000 years, the lake stayed about the same size but briefly grew 10 times larger on two separate occasions.
Background
Researchers from the University of Utah have discovered a significant body of freshwater hidden beneath the Great Salt Lake playa, a finding that could reshape our understanding of subsurface water flow in the region.
What's confirmed
- “There are beneficial effects of this groundwater that we need to understand before we go extracting more of it. A first-order objective is to understand whether we could use this freshwater to wet dust hotspots and douse them in a meaningful way without perturbing the freshwater system too much,” Johnson said.
- “We were able to answer the question of how deep this potential reservoir is, and what its spatial extent is 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 Zhdanov, a distinguished professor of geology & geophysics and director of the Consortium for Electromagnetic Modeling and Inversion, or CEMI.
What's still developing
- This latest paper measured electrical resistivity to a depth of about 100 meters via airborne electromagnetic surveys to discern freshwater from brine, which is far more electrically conductive.
- Can’t-miss innovations from the bleeding edge of science and tech The Great Salt Lake is harboring an unexpected secret: a huge stash of water that’s decidedly not salty.
- That clued them in to an even bigger find: a sudden drop in the lake’s subterranean layer called a basement, going from just a few hundred yards deep to over 2.5 miles.
- We can often understand more about the future by looking into the past – and in the case of a new study published in Paleoceanography and Paleoclimatology, almost 240,000 years into the history of the Great Salt Lake in Utah.
- Utah geoscientists begin characterizing newly discovered mountain-sourced groundwater that extends thousands of feet beneath the playa.
- This groundwater fills tiny pore spaces within sediments that occupy the basin west of the Wasatch Mountains and lies beneath a salty layer roughly 30 feet thick.
- This previously unknown zone is now referred to as the “saltwater lens,” and its discovery is reshaping scientists’ understanding of subsurface water flow in the region.
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- His team also characterized the spatial extent of the freshwater reservoir beneath Farmington Bay and studied the potential depth of freshwater-saturated sediments by delineating the basement structure.
- “Red means very conductive, blue is resistive,” Zhdanov said while explaining this map, seen to the right.
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