Cleveland, Mar 13: As Utah’s Great Salt Lake continues to shrink due to climate change and upstream water diversions, new scientific research has uncovered surprising findings beneath its exposed lakebed. A team of geoscientists from the University of Utah has identified a complex underground system that includes a largely freshwater aquifer hidden beneath the playa.
Since 1989, the lake has lost nearly 70% of its surface area, exposing about 800 square miles of mudflats and playa. While the lake’s decline poses serious environmental concerns, it has also created new opportunities for scientific research into the geology and hydrology beneath the lakebed.
The research team, led by geophysicist Mike Thorne, used advanced geophysical techniques including electrical resistivity tomography (ERT) to map underground structures along the southern and eastern edges of the lake. The technology works by sending electrical currents through the ground to measure resistance levels, allowing scientists to identify different underground materials and determine groundwater salinity.
The findings revealed a highly complex subsurface environment. In some areas, thick layers of salty groundwater lie just below the surface, while other locations contain freshwater only a few meters underground. Near the historic Saltair area, researchers also identified a mineral layer of mirabilite—a sodium sulfate deposit—that traps briny groundwater beneath it.
In contrast, areas closer to Lee’s Creek Natural Area and Farmington Bay show signs of shallow freshwater sources likely fed by mountain runoff from the nearby Wasatch Mountains or possibly remnants of ancient Lake Bonneville, which covered the region roughly 14,000 years ago.
The research is part of a larger hydrology project funded by the Utah Department of Natural Resources, aimed at understanding how groundwater systems interact with the shrinking lake. Scientists hope to determine how much freshwater exists beneath the playa and whether it could be used without damaging the fragile ecosystem.
“These discoveries show that the underground landscape beneath the Great Salt Lake is far more complex than previously thought,” said Thorne, associate professor in the University of Utah’s Department of Geology & Geophysics. “What appears to be a flat and uniform surface actually hides significant variability below.”
The study also contributes to broader scientific understanding of terminal lakes—bodies of water with no outlet where salts accumulate over time. Such lakes are found across the Great Basin and around the world, but many are rapidly shrinking due to water diversions and climate change.
Researchers believe the findings could help guide future environmental management strategies for the Great Salt Lake while also advancing global knowledge about groundwater systems beneath terminal lakes.
Further studies are underway to better understand how freshwater and saltwater interact beneath the lakebed, including rare natural processes where dense saltwater sinks through lighter freshwater layers.
The research findings were recently published in the journal Geosciences, with University of Utah graduate student Mason Jacketta serving as lead author.
