💧 Unexpected: a vast freshwater reservoir beneath the Great Salt Lake

Beneath the salt-saturated waters of the Great Salt Lake in the United States lies a major surprise: a vast freshwater reservoir extending as a deep network.

To unveil this network, a team from the University of Utah used an airborne prospecting method: electromagnetic surveys. This technique enabled mapping geological formations up to several kilometers beneath the lakebed, revealing the presence of freshwater in areas previously considered entirely saline.


The collected data show that this freshwater permeates the sediments to a thickness that can reach three to four kilometers (approximately 1.9 to 2.5 miles). Unexpectedly, it extends well beyond the shores, a pattern that changes the understanding of groundwater flows in this type of environment. This configuration indicates that the water comes from deep sources, and not from the lake margins as previously assumed.


This discovery has practical applications, particularly for limiting dust pollution. The drop in water level has indeed exposed vast areas of lakebed, sources of toxic particles affecting surrounding populations. The freshwater could be used to moisten these areas and mitigate harmful emissions, offering a solution without excessively affecting the water balance.

The airborne method used is based on measuring electrical resistivity. By flying over the lake, a specially equipped helicopter measures electromagnetic fields, which allows differentiating freshwater, less conductive, from saltwater. This non-invasive approach provides a precise image of the underground layers, helping to delineate the boundaries between different water types and deep geological structures.

Researchers plan to extend these surveys to the entire Great Salt Lake. A comprehensive mapping could help plan water resource management and serve as a reference for other lakes around the world, where similar reserves might exist.