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The Great Salt Lake is slowly drying up, dropping by more than half its size since just 1986.<\/p>\n
As some lakebed has been exposed, reed-filled mounds have appeared, which suggest the presence of freshwater lurking beneath the surface.<\/p>\n
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.<\/p>\n
Utah\u2019s 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<\/a>, 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<\/a>, 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<\/a>, the state receives nearly 95 percent of its freshwater from snowpack.<\/p>\n Unfortunately, it\u2019s no secret that the Great Salt Lake is struggling<\/a>. While its 1,000-square-mile expanse might sound impressive on paper, it\u2019s less than half the size that the lake was in 1986, and the salt water\u2019s<\/a> absence has exposed nearby Salt Lake City to increased levels of toxic dust. However, the lake\u2019s struggles have also revealed something else that scientists didn\u2019t 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.<\/p>\n 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<\/a> 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<\/a>.<\/p>\n \u201cWe were able to answer the question of how deep this potential reservoir<\/a> is, and what its spatial extent is beneath the eastern lake margin,\u201d Michael Zhdanov, the lead author of the study from the University of Utah, said in a press statement<\/a>. \u201cIf you know how deep, you know how wide, you know the porous space, you can calculate the potential freshwater volume.\u201d<\/p>\n 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<\/a> 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.<\/p>\n By combining this data with additional magnetic<\/a> measurements, Zhdanov and his team successfully peered deeper beneath Farmington Bay, confirming that the freshwater may extend as far as four kilometers down.<\/p>\n \u201cThere are beneficial effects of this groundwater<\/a> that we need to understand before we go extracting more of it,\u201d Bill Johnson, a co-author of the study from the University of Utah, said in a press statement. \u201cA 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.\u201d<\/p>\n For now, scientists can\u2019t 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\u2019s freshwater treasure<\/a>.<\/p>\n