The Great Salt Lake, the largest saltwater lake in the Western Hemisphere, is a terminal body of water that has sustained a unique ecosystem and regional economy for millennia. Historically known for its vast, shallow expanse, the lake is now experiencing a catastrophic decline in its water levels. This dramatic shrinking threatens to transform the region’s environment, economy, and public health.
Measuring the Magnitude of Decline
The question of “how much” the Great Salt Lake has shrunk is answered by several alarming quantitative metrics. The lake’s surface elevation has dropped nearly 19 feet below its average natural level since 1850, a decline that accelerated significantly after the year 2000. This drop culminated in the lake reaching its lowest recorded elevation of 4,188.3 feet above sea level in November 2022.
This loss of elevation has translated directly into a massive reduction in the lake’s footprint. The Great Salt Lake has lost 60% of its total surface area, shrinking from a high of approximately 3,300 square miles in the mid-1980s to a low of less than 950 square miles. The shallow nature of the lake means that small vertical drops result in vast stretches of newly exposed lakebed, changing islands into peninsulas and dramatically altering the shoreline.
The most severe measure of the decline is the sheer volume of water that has disappeared. The Great Salt Lake has lost an estimated 73% of its water volume. Since 2020, the lake has been losing water at an accelerated rate, averaging a deficit of about one million acre-feet annually. In total, approximately 26 million acre-feet of water have been lost from the lake itself, a staggering measure of the water deficit. This rapid and sustained loss of volume highlights the severity of the crisis compared to historical fluctuations.
The Role of Water Diversion and Climate
The primary drivers of the lake’s steep decline are a combination of excessive water diversion for human use and the intensifying effects of a changing climate. Human consumption has been estimated to lower the lake’s level by about 11 feet. Water inflows to the lake’s tributaries have declined by approximately 39% since 1850, a direct result of these upstream diversions.
This upstream water usage is predominantly for agriculture, which accounts for the vast majority of all diverted water in the region, with estimates ranging from 70% to 82% of Utah’s total diverted water. The Bear, Weber, and Jordan rivers, which are the main sources of inflow, are heavily tapped for irrigation and municipal needs. Consequently, the Great Salt Lake received less than a third of its natural streamflow between 2020 and 2023, severely limiting its ability to naturally recover.
Compounding the effects of diversion are regional climatic factors. Prolonged drought conditions and rising regional temperatures increase the rate of evaporation from the lake’s surface. Furthermore, a warmer climate means that a greater percentage of precipitation falls as rain rather than snow, reducing the slow, sustained release of water from the mountain snowpack that historically fed the lake during the spring and summer months.
Disrupting the Lake’s Ecosystem
The loss of water volume has directly led to a crisis of rising salinity, which is disrupting the lake’s delicate ecosystem. The Great Salt Lake is a terminal lake, and as water evaporates, its salt content becomes highly concentrated. The salinity in the main body of the lake has climbed to levels around 19%, significantly higher than ocean water.
This hypersaline environment threatens the lake’s foundation species: brine shrimp and brine flies. These invertebrates are highly adapted to salt water, but their life cycles are inhibited by extremely high salinity levels. A collapse in the populations of brine shrimp and brine flies would destroy the primary link in the lake’s food chain.
The Great Salt Lake is a globally significant stopover point for millions of migratory birds along the Pacific Flyway. These birds, including phalaropes, eared grebes, and various shorebirds, rely on the vast quantities of brine shrimp and brine flies for sustenance during their annual migrations. As the lake shrinks and the invertebrate populations decline, the birds lose both their feeding grounds and their nesting habitats within the surrounding wetlands, which are also dependent on the lake’s water levels.
Air Quality and Economic Stability
The shrinking Great Salt Lake poses direct threats to human health and the regional economy. The vast, newly exposed lakebed presents a significant air quality hazard, often referred to as “lakebed dust”. When high winds sweep across this dry surface, they carry fine sediment into the air and toward the densely populated Wasatch Front.
This dust is not merely irritating; it contains elevated concentrations of heavy metals such as arsenic, lead, and mercury, which have accumulated in the lakebed over millennia. The inhalation of this toxic dust poses a severe public health concern for nearby communities, potentially increasing the risk of respiratory illnesses and other long-term health issues. The exposure of these materials represents a lasting environmental consequence of the lake’s decline.
The lake also underpins a significant portion of the regional economy, contributing an estimated $2.5 billion annually through various industries. Mineral extraction companies depend on the hypersaline water to harvest salts, magnesium, and potash. As water levels drop, the viability of withdrawing water for these industrial operations decreases, threatening a major source of employment and commerce. Similarly, the decline impacts tourism and recreation, including boating and the once-thriving bird watching activities.