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The Great Salt Lake is harboring an unexpected secret: a huge stash of water that\u2019s decidedly not salty.<\/p>\n
A team of researchers who x-rayed its subterranean structures<\/a> discovered that lurking below its briny surface is a vast and miles-deep reservoir of freshwater.<\/p>\n The findings, detailed in a new study<\/a> in the journal Scientific Reports, upend expectations that any freshwater presence would be small and relegated to the lake\u2019s outskirts, dumped there by nearby mountains.\u00a0In reality, it appears that possibly the entire saltwater lake is undergirded by freshwater.<\/p>\n \u201cWe were able to answer the question of how deep this potential reservoir is, and what its spatial extent is beneath the eastern lake margin.\u00a0 If you know how deep, you know how wide, you know the porous space, you can calculate the potential freshwater volume,\u201d said lead author Michael Zhdanov, a geophysicist at the University of Utah, in a statement<\/a> about the work.<\/p>\n Scientists had a sneaking suspicion that there was a hidden freshwater presence with the sudden appearance in the past few years of large mounds of reeds popping up in regions of dry exposed lakebed called playa.<\/p>\n To probe the depths beneath the lake, the researchers conducted what\u2019s known as airborne electromagnetic surveys by flying over the saltwater body in a helicopter and pointing instruments that measure the electrical conductivity on the ground. The resulting signals help distinguish between salt and fresh water \u2014 salt makes the liquid it\u2019s suspended in far more conductive \u2014 and tease out the composition of the rocks and soils.\u00a0<\/p>\n Some 154 miles of flying later, the team had collected the data they were looking for. After using it to create a map of the lake, they found that spikes of resistive fresh water were turning up everywhere.\u00a0<\/p>\n That clued them in to an even bigger find: a sudden drop in the lake\u2019s subterranean layer called a basement, going from just a few hundred yards deep to over 2.5 miles. The freshwater appears to be saturating sediments trapped in this region, forming a deep reservoir.<\/p>\n Bill Johnson, a UT hydrologist and coauthor of the study, called the findings \u201cunexpected.\u201d<\/p>\n \u201cWhat we would normally expect as hydrologists is that the brine would occupy the entire volume underneath that lake,\u201d he explained in an interview<\/a> on KPCW\u2019s Cool Science Radio show, cited in the university release. \u201cIt\u2019s denser than the freshwater. You\u2019d expect the freshwater from the mountains to come in somewhere at the periphery.\u201d<\/p>\n \u201cBut we find it\u2019s coming in towards the interior,\u201d he added. \u201cAnd there\u2019s what appears to be a deep volume of this freshwater coming in underneath that saline lens.\u201d<\/p>\n The aerial survey spanned only a fraction of the huge lake\u2019s area, making it difficult to draw hard conclusions of this reservoir\u2019s true size. That it\u2019s there at all, however, has scientists hooked.<\/p>\n \u201cThis is why we need to survey the entire Great Salt Lake,\u201d Zhdanov said. \u201cThen we\u2019ll know the top and the bottom.\u201d<\/p>\n