Researchers Analyzed Great Salt Lake History

A new 2026 study examined 240,000 years of lake data to identify past freshwater periods.

Updated on Oct. 8, 2026 in Geography

Isometric editorial illustration showing a single layered geological sediment core segment on an arid, salt-textured surface. — Researchers identified two prehistoric eras, Little Valley and Lake Bonneville, when the Great Salt Lake was a large, freshwater system. AI Illustration. Upload story photo >

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Scientists recently published a study identifying two historical eras where the Great Salt Lake was larger and less saline. The research provided a retrospective look at the lake through the analysis of a 120-meter sediment core.

Why it matters

This long-term perspective helps researchers understand the environmental fluctuations of the region. By mapping these ancient shifts, scientists gain context for how the lake responded to different climate conditions over deep time.

Researchers analyzed a 120-meter sediment core from the lake bed to reconstruct the history of the basin. The study utilized chemical signals from microbes within the core to estimate changes in salinity across 240,000 years.

The details

The study identified two distinct periods, Little Valley and Lake Bonneville, where the basin held significantly more water than its current 4,144 square kilometers. During these eras, the lake functioned as a freshwater system, a stark contrast to the modern environment which is up to 10 times saltier than seawater.

140,000 to 135,000 years ago: Little Valley lake period occurred.
30,000 to 16,000 years ago: Lake Bonneville lake period occurred.
2026: The research study was published.

The Big Picture

This study updates the paleolimnological reconstruction of the Bonneville Basin by providing new data on salinity transitions. The findings shift scientific understanding of how the basin oscillated between freshwater and hypersaline states throughout the Pleistocene.

Understanding these historical cycles provides essential context for modern water management in Utah. By studying how the lake functioned in the past, researchers can better project future environmental changes and the sustainability of the current water level.

The takeaway

The Great Salt Lake is far more dynamic than its current state suggests. Residents can better understand modern water issues by recognizing that the basin has experienced massive, long-term fluctuations in both volume and composition.