Scientists Just Found a Massive Freshwater Reservoir Hidden Beneath the Great Salt Lake
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Here’s what you’ll learn when you read this story:
- The Great Salt Lake is slowly drying up, dropping by more than half its size since just 1986.
- As some lakebed has been exposed, reed-filled mounds have appeared, which suggest the presence of freshwater lurking beneath the surface.
- A new study conducting aerial electromagnetic surveys confirmed that at least a part of Farmington Bay is home to a large groundwater reservoir, but scientists are unsure how far this reservoir extends.
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Utah’s Great Salt Lake is one of the most important bodies of water in the western U.S. For one, the 1,000-square-mile lake is a critical layover for the Pacific Flyway, with some 12 million birds from more than 300 species spending time in its waters every year. For another, the lake adds moisture to passing storms, which eventually dump their contents onto the mountains that lie to the east, where ski slopes reign supreme. According to the Utah Division of Water Resources, the state receives nearly 95 percent of its freshwater from snowpack.
Unfortunately, it’s no secret that the Great Salt Lake is struggling. While its 1,000-square-mile expanse might sound impressive on paper, it’s less than half the size that the lake was in 1986, and the salt water’s absence has exposed nearby Salt Lake City to increased levels of toxic dust. However, the lake’s struggles have also revealed something else that scientists didn’t expect. In recent years, circular mounds covered in 15-foot-tall thickets of reeds have appeared along the dried-out bed of an area known as Farmington Bay, suggesting that at least some level of groundwater lies beneath the lake.
To understand what exactly has fueled these reed-filled mounds, a team of geophysicists from the University of Utah conducted airborne electromagnetic (AEM) surveys in order to X-ray structures beneath Farmington Bay. They found that freshwater permeates the sediments beneath the hypersaline lakebed up to four kilometers (or roughly 13,000 feet) deep into the ground. The results of the study were published in the journal Scientific Reports.
“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,” Michael Zhdanov, the lead author of the study from the University of Utah, said in a press statement. “If you know how deep, you know how wide, you know the porous space, you can calculate the potential freshwater volume.”
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To accurately capture this volume, Zhdanov and his team hired a geophysical crew to conduct 10 east-west surveys, covering 154 miles in total. Using a helicopter outfitted with electromagnetic equipment, these surveys accurately captured the conductivity of the overlying brine, as well as the resistive fresh water that lies beneath. Stitching together this data into a comprehensive map showing the saline-freshwater boundary, the researchers noticed that the phragmite (reed) mounds appeared directly where freshwater pushed through the briney layer of the lake.
By combining this data with additional magnetic measurements, Zhdanov and his team successfully peered deeper beneath Farmington Bay, confirming that the freshwater may extend as far as four kilometers down.
“There are beneficial effects of this groundwater that we need to understand before we go extracting more of it,” Bill Johnson, a co-author of the study from the University of Utah, said in a press statement. “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.”
For now, scientists can’t say for certain if this newly discovered freshwater reservoir is the exception or the rule for the rest of the Great Salt Lake. Future aerial surveys will need to expand beyond this tiny sliver in order to capture the full extent of the lake’s freshwater treasure.
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But for the first time in a long time, there is a little bit of good news for the largest terminal lake in the U.S.
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