The Great Salt Lake, the largest saltwater lake in the Western Hemisphere, is a terminal lake, meaning it has no outlet and only loses water through evaporation. This unique characteristic has made its current rapid decline a crisis, setting off a chain reaction of ecological and economic threats across the region. The lake is disappearing due to a combination of long-term human water diversion and climate-driven factors that have significantly reduced the inflow of fresh water. The resulting loss of surface area and increased salinity have destabilized the entire ecosystem and created a serious public health hazard for nearby communities.
Measuring the Decline: Record Lows and Current Levels
The Great Salt Lake’s size is sensitive to water level changes because its basin has a very shallow, gently sloping floor. Historically, the lake maintained an average elevation of around 4,200 feet above sea level, covering approximately 1,700 square miles. This equilibrium has been severely disrupted by human activity over the past century.
The lake has repeatedly broken its own low-water records in recent years, demonstrating the severity of the decline. The historic low was officially reached in November 2022, when the water elevation dropped to 4,188.5 feet. This record-low elevation represents a massive reduction in the lake’s footprint.
The drop from the historical average of 4,200 feet has led to a major loss in volume and surface area. At its lowest point, the lake’s surface area shrank by roughly two-thirds from its historical average size. Because the lake is shallow, every foot of elevation loss exposes a vast amount of previously submerged lakebed, drastically affecting the total water volume.
Primary Drivers of Water Loss
The primary reason for the Great Salt Lake’s decline is the substantial reduction of water flowing into it from its three major tributaries: the Bear, Weber, and Jordan Rivers. Studies indicate that human water consumption is responsible for an estimated 67% to 73% of the current lake-level decline. This diversion has effectively lowered the lake’s surface by approximately 11 feet over the long term.
Agriculture is the largest consumer, accounting for nearly two-thirds of the total diverted water in the Great Salt Lake Basin. This water is drawn upstream for irrigation before it can reach the lake. The municipal and industrial sector is responsible for roughly 25% of the remaining diverted water, used for city supplies and various extraction processes.
The second major factor is climate change, which contributes an additional 8% to 11% to the lake’s decline through warming and drought. Higher temperatures increase the rate of evaporation from the lake’s surface and reservoirs upstream. Warming trends have also reduced the mountain snowpack, a major source of fresh water, leading to lower spring runoff into the tributaries.
Ecological and Industrial Impacts of Increased Salinity
As the lake’s volume shrinks, the remaining water becomes concentrated with salt, resulting in hyper-salinity that threatens the food web. The South Arm (Gilbert Bay), where river water enters, is the center of the lake’s ecosystem. Its health relies on a balanced salinity range, ideally between 90 and 130 grams of salt per liter. Salinity levels above 180 grams per liter (18%) begin to disrupt the algae and cyanobacteria that form the foundation of the ecosystem.
This hyper-salinity is devastating to the brine shrimp, a keystone species in the lake. When the water becomes too salty, the shrimp struggle to reproduce and maintain their populations. The collapse of the brine shrimp population has a cascading effect on the millions of migratory birds, such as eared grebes and phalaropes, that rely on the shrimp and brine flies for food along the Pacific Flyway.
The low water level and rising salinity also pose a direct threat to the lake’s billion-dollar mineral extraction industry. Companies harvest various minerals, including potassium sulfate (potash), magnesium, and salt, by pumping brine into shallow solar evaporation ponds. When the lake level drops, companies must invest millions to extend intake structures, dredge harbors, and dig long canals to access the brine. Restricted water flow, especially between the two arms of the lake, complicates achieving the precise salinity needed for efficient mineral extraction.
Hazards of the Exposed Lakebed
The loss of water has exposed hundreds of square miles of lakebed (the playa), creating a significant public health risk. This exposed sediment contains high concentrations of heavy metals and neurotoxins that have accumulated over centuries as a terminal basin for contaminants. Studies have confirmed the presence of arsenic, lead, copper, and mercury in the dried sediment.
When high winds sweep across the exposed playa, these toxic sediments are aerosolized into fine particulate matter (PM2.5 and PM10). This “lake effect dust” is then carried toward the Wasatch Front, where more than two million people reside. The dust particles, particularly those laced with arsenic and other metals, can be inhaled deep into the lungs.
The inhalation of this toxic dust is linked to increased rates of respiratory illnesses, including asthma, lung inflammation, and the potential for long-term damage like heart disease. Dust settling on the Wasatch Mountains further complicates the issue by darkening the snowpack surface. This darker snow absorbs more solar radiation, accelerating spring snowmelt and diminishing the overall water supply for the region.