A potentially huge underground reservoir of freshwater beneath the Great Salt Lake is coming into sharper focus with a new study that used airborne electromagnetic (AEM) surveys to X-ray geologic structures under Farmington Bay and Antelope Island off the lake\u2019s southeastern shore.<\/p>\n
An analysis of this data by University of Utah geophysicists shows that freshwater saturates the sediments beneath the lake\u2019s hypersaline surface to depths of 3 to 4 kilometers, or about 10,000 to 13,000 feet. The helicopter-borne geophysical survey was conducted last year after U scientists documented freshwater welling up under pressure at several spots on the lake\u2019s exposed playa in Farmington Bay, manifesting as strange phragmites-choked mounds<\/a>.<\/p>\n The study demonstrated for the first time the ability of AEM methods to detect freshwater underneath thethin layer of conductive salt water at the surface of the Great Salt Lake, according to lead author Michael Zhdanov<\/a>.\u00a0 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.<\/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. \u00a0If you know how deep, you know how wide, you know the porous space, you can calculate the potential freshwater volume,\u201d said Zhdanov, a distinguished professor of geology & geophysics and director of the Consortium for Electromagnetic Modeling and Inversion<\/a>, or CEMI.<\/p>\n A larger state-funded research effort focused on a newly discovered aquifer<\/p>\n The results appear in the Nature-affiliated journal Scientific Reports<\/a>. This study is part of a larger research project led by the U\u2019s Department of Geology & Geophysics and funded by the Utah Department of Natural Resources to understand the groundwater beneath Great Salt Lake, the largest terminal lake in the Western Hemisphere.<\/p>\n Overseen by some of the geology department\u2019s most senior faculty and their graduate students, this effort has already resulted in two other important papers, with more to follow.<\/p>\n The evidence produced in this new study suggests that freshwater is entering the subsurface toward the lake\u2019s interior, not its periphery as would be expected, according to hydrologist Bill Johnson, a co-author on all the Great Salt Lake groundwater papers.<\/p>\n \u201cThe unexpected part of this wasn\u2019t the salt lens that we see near the surface across the playa. It\u2019s that the freshwater underneath it extends so far in towards the interior of the lake and possibly under the entire lake. We don\u2019t know,\u201d Johnson said on a recent appearance on KPCW\u2019s Cool Science Radio<\/a> show. \u201cWhat we would normally expect as hydrologists is that the brine would occupy the entire volume underneath that lake. It\u2019s denser than the freshwater. You\u2019d expect the freshwater from the mountains to come in somewhere at the periphery. But we find it\u2019s coming in towards the interior. And there\u2019s what appears to be a deep volume of this freshwater coming in underneath that saline lens.\u201d<\/p>\n A potential water source to mitigate dust pollution<\/p>\n These studies were triggered by the appearance in recent years of circular mounds, each 50 to 100 meters in diameter and covered with 15-foot-tall thickets of reeds, on the dried-out bed of Farmington Bay. The lake\u2019s declining water levels have exposed 800 square miles of lake playa, which is now becoming a major source of dust pollution blowing into Utah\u2019s population centers.<\/p>\n Johnson, a professor of geology and geophysics, wants to explore whether the artesian groundwater could be safely tapped to mitigate the dust, which contains toxic metals.<\/p>\n \u201cThere 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,\u201d Johnson said. \u201cTo me, that\u2019s a primary objective because it\u2019s very practical and it\u2019s unlikely we\u2019ll be able to fill Farmington Bay and other parts of the playa enough to avoid some dust spots appearing at the higher elevations. This would be a great way to get at that.\u201d<\/p>\n Johnson and his Utah colleagues, including Mike Thorne and Kip Solomon, are seeking funding to expand the groundwater studies to cover a much larger portion of the lake.<\/p>\n 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. To see if this could be done, Johnson and Zhdanov hired a geophysical crew from Canada to fly electromagnetic equipment dangled under a helicopter in February 2025. The helicopter flew 10 east-west survey lines spanning Farmington Bay and across the northern portion of Antelope Island, for a total of 154 miles.<\/p>\n Looking under the playa<\/p>\n Zhdanov\u2019s team analyzed the resulting data to create a map of the saline-freshwater interface. It showed how one phragmites mound sat above a spot where freshwater pushed through a gap in the impervious layer underlying the lake.<\/p>\n \u201cRed means very conductive, blue is resistive,\u201d Zhdanov said while explaining the map. \u201cYou clearly see near surface is saline water, 10 meters underneath is resistive freshwater. You see clearly it\u2019s everywhere.\u201d<\/p>\n Zhdanov\u2019s research group CEMI has developed a technique to build 3D images of Earth\u2019s subsurface by integrating electromagnetic data gathered aerially with magnetic measurements. Applied in this study, the researchers were able to create a tomographic image extending deep beneath Farmington Bay, providing critical insights into its geological and hydrological structure.<\/p>\n The results of the magnetic data inversion show that the basement under the Farmington Bay playa is relatively shallow, less than 200 meters down, but then abruptly plunges to 3 to 4 kilometers. The drop-off, which occurs under the phragmites mound, represents a significant structural boundary that should be more fully explored.<\/p>\n \u201cThis is why we need to survey the entire Great Salt Lake. Then we\u2019ll know the top and the bottom,\u201d Zhdanov said. \u201cTo study the top, we use airborne electromagnetic methods, which give us the thickness of the saline layer and where the freshwater starts under the saline layer. To study the bottom, we use magnetic data. We use different techniques to study the vertical extent of these freshwater-saturated sediments, to find the\u00a0 depth to the basement.\u201d<\/p>\n This pilot study covered just a sliver of the lake, but Zhdanov believes his team can fly airborne electromagnetic survey lines spanning the lake\u2019s entire 1,500-square-mile footprint.<\/p>\n A lake-wide airborne survey could help guide regional water-resource planning and inform similar searches for freshwater under terminal lakes worldwide.<\/p>\n The study was published Feb. 27 in Scientific Reports under the title, \u201cAirborne Geophysical Imaging of Freshwater Reservoir Beneath the Eastern Margin of Great Salt Lake<\/a>.\u201d Co-authors include Michael Jorgensen, Bill Johnson, \u00a0and Kip Solomon of the U Department of Geology & Geophysics, and Leif Cox of TechnoImaging<\/a>, a university spinoff founded by Michael Zhdanov in 2005. \u00a0Funding came from Utah Department of Natural Resources, the Great Salt Lake Commissioners\u2019 Office, and the Consortium for Electromagnetic Modeling and Inversion (CEMI) at the University of Utah.<\/p>\n","protected":false},"excerpt":{"rendered":"A potentially huge underground reservoir of freshwater beneath the Great Salt Lake is coming into sharper focus with…\n","protected":false},"author":2,"featured_media":551513,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[64,63,272829,5440,128,121286],"class_list":["post-551512","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-au","tag-australia","tag-great-salt-lakegeophysicsmichael-zhdanovaemairborne-electromagnetic-surveysgroundwater","tag-newswise","tag-science","tag-university-of-utah"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/551512","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/comments?post=551512"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/551512\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media\/551513"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media?parent=551512"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/categories?post=551512"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/tags?post=551512"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}