Utah’s Great Salt Lake at sunset. (Credit: © Minyun Zhou | Dreamstime.com)
In a nutshell
- The Great Salt Lake reached its lowest level in 170+ years primarily due to reduced river flow, which caused three times more water loss than any other factor. However, increased evaporation from warming temperatures was necessary for the lake to hit its 2022 record low.
- As the lake shrinks, it exposes dry lakebeds that can release toxic dust into the air, threatening the health of 1.2 million Salt Lake City metropolitan residents. The decline also endangers $1.9 billion in annual economic benefits and the region’s winter sports industry.
- While increasing river flow could help restore lake levels quickly, long-term recovery faces challenges from rising temperatures that continue to increase evaporation rates. This makes comprehensive water management strategies crucial for the lake’s future.
PORTLAND, Ore. — Utah’s Great Salt Lake, the largest saltwater lake in the Western Hemisphere, hit a troubling milestone in 2022, dropping to its lowest water level since record-keeping began in 1847. This unprecedented decline threatens not just the lake’s ecosystem, but also poses serious risks to public health, the regional economy, and Utah’s winter sports industry.
Scientists from Portland State University and Oregon State University recently investigated why the lake has reached such historically low levels. Their findings, published in Geophysical Research Letters, point to two main culprits: decreased water flowing into the lake from rivers and streams, combined with increasing evaporation as temperatures rise.
“The lake has a lot of social and economic relevance for the region and Utah,” says Siiri Bigalke, the lead author and a Ph.D. candidate in PSU’s Earth, Environment and Society program, in a statement. Bigalke began the research while a master’s student at Utah State University. “It provides over $1.9 billion in annual economic revenue, serves as a vital feeding ground for millions of migratory birds and enhances snowfall over the Wasatch Mountain Range.”
To understand the lake’s history, imagine filling a bathtub where the water level changes based on what flows in and what drains out. Before 2021, the lowest water level was recorded in 1963. Then came a remarkable turnaround in the 1980s, when heavy rains and snowmelt filled the lake so much that it caused flooding along the eastern shoreline. The water rose so high that in 1987, officials had to pump excess water into the nearby desert to prevent damage to surrounding communities.
The research team created a mathematical model to track three main factors affecting the lake’s water level: how much water flows in from rivers, how much rain falls directly on the lake, and how much water evaporates into the air. They ran different scenarios to understand how each factor contributed to the lake’s decline.
Their findings revealed that reduced river flow played the biggest role, causing about three times more water loss than increased evaporation, which was the second most important factor. Changes in rainfall had surprisingly little impact. However, the researchers discovered something crucial: while less river water was the main driver of decline, the lake wouldn’t have hit its record low without the increased evaporation caused by warming temperatures.
“The contribution from warming to the evaporation is significant,” explains Paul Loikith, an associate professor of geography and director of PSU’s Climate Science Lab. “Without the warming trend, 2022 wouldn’t have been record low. Even though streamflow is dominant, the increase in evaporation was necessary to reach the record low.”
This creates an interesting puzzle for the future. As the region continues to warm, more water will evaporate from the lake’s surface. But as the lake shrinks, there’s less surface area from which water can evaporate. This self-limiting process makes it challenging to predict exactly how the lake will change in coming years. The threat of toxic dust also poses a major problem for the 1.2 million people living in or around Salt Lake City.
“As the lake shrinks, it’s exposing this dry lakebed that could possibly increase dust events into the metropolitan area, affecting the air quality for nearby residents,” adds Bigalke.
The good news is that the lake responds quickly when river flows increase, suggesting that better water management could help restore lake levels. The challenge lies in balancing human water needs with maintaining enough flow to sustain the lake, all while facing the ongoing effects of warming temperatures.
With the 2034 Winter Olympics set for Salt Lake City, the lake will undoubtedly serve as the centerpiece for the games and ceremonies. However, how much of the water will have evaporated between now and then will remain a serious concern.
Paper Summary
Methodology
The researchers created a mass-balance model that calculated year-to-year lake volume changes based on water inputs (streamflow and precipitation) and outputs (evaporation). They used data from three major tributaries – the Bear River, Jordan River, and Weber River – along with precipitation records from two weather stations and evaporation data from the European Center for Medium-Range Weather Forecasts. The model ran four simulations: one with all variables at their mid-20th century average, and three others where one variable followed actual observations while the others remained fixed.
Results
Low streamflow accounted for 3.64 cubic kilometers of water loss compared to the equilibrium state, while increased evaporation led to 1.27 cubic kilometers of loss. Precipitation changes only resulted in 0.40 cubic kilometers of water loss. The study found that streamflow variability dominates annual volume changes, but the warming-induced increase in evaporation was necessary for reaching the record low.
Limitations
The research excluded approximately 7% of streamflow from numerous small streams and didn’t account for groundwater inputs, which have been previously estimated at less than 2% of annual average water inputs. The model also used a relatively coarse time step of one year, which could introduce some uncertainty during periods of rapid change in lake surface area.
Discussion and Takeaways
The study represents the first comprehensive, peer-reviewed quantification of factors contributing to the Great Salt Lake’s decline. This scientific milestone provides crucial baseline data for policymakers and resource managers working to address the crisis.
The findings suggest that while streamflow management could lead to rapid volume recovery, continued warming poses a significant long-term challenge. The study emphasizes the need for comprehensive water management strategies that account for both immediate streamflow needs and long-term climate change impacts.
Beyond the ecological and economic impacts, the study highlights urgent public health concerns. As the lake recedes, exposed lakebeds can release dust containing various minerals and compounds that could affect air quality in the Salt Lake City metropolitan area, potentially impacting over a million residents.
The study’s findings have particular relevance for Utah’s winter sports industry. The lake’s effect on local weather patterns, particularly in creating enhanced snowfall over nearby mountains, plays a crucial role in supporting the region’s world-class ski resorts and its successful bid for the 2034 Winter Olympics.
Funding and Disclosures
The study was supported by NSF Grants AGS-2206997 and AGS-2024212. The researchers acknowledged contributions from Dr. Deepti Singh, Dr. Xiaoyu Bai, and members of the Utah State University Plants, Soils, and Climate department and the Utah State Climate Adaptation Science program.
Publication Information
Published in Geophysical Research Letters (2025), Volume 52, under the title “Explaining the 2022 Record Low Great Salt Lake Volume” by Siiri Bigalke, Paul Loikith, and Nicholas Siler from Portland State University and Oregon State University.
