Utah’s Great Salt Lake is disappearing

As a megadrought continues to affect the US southwest, Utah's Great Salt Lake dipped to its lowest recorded water level last month, requiring the rapidly expanding metropolis to reduce its water consumption. Large swaths of lakebed are now visible due to the decline in water levels between 1985 and 2022, as shown in satellite photographs.

The Great Salt Lake's surface water elevation decreased to an average of 1277 m above sea level, the lowest level since records first began to be kept in the middle of the 1800s, according to information from the US Geological Survey. This decrease in water level has caused the lake to lose over half of its historical average surface area, exposing almost 2000 square kilometers of lakebed—an area the same size as Tenerife.

According to the US Geological Survey, the lake only has little more than one-fourth as much water in it as it had in 1987, when it was at its highest level. Two of the primary causes of the lake's decrease are water use and the drought brought on by climate change.

The lake experiences cyclical cycles of water loss and replenishment after being refilled by rain and snowmelt. Officials claim that water entering the lake is outweighed by evaporation and depletion. Up until early fall or into the next winter, when incoming water equals or surpasses evaporative losses, it is anticipated that the lake's water levels will continue to drop.

The lakebed has been exposed in significant areas due to the lake's water levels dropping between 1985 (left) and 2022 (right), as shown in the satellite photos below.

The Great Salt Lake's diminishing water levels have a terrible impact on the region's economy, environment, and population. The lake produces snowfall, serves as a haven for a large number of migrating birds and other species, and provides millions of dollars in economic growth through mining and tourism.

The Great Salt Lake is one of the most salinized inland bodies of water in the world and the biggest saltwater lake in the western hemisphere. Millions of birds depend on flies and brine shrimp, which are endangered as the lake gets smaller and saltier, as a source of food.

The local air quality is also impacted by falling water levels. The dry soil causes an increase in dust in the air as the lake bottom dries up and more lakebed becomes visible. Copper, arsenic, and other harmful heavy metals that have collected in the lake are mixed throughout the dust, much of it leftover from the area's mining history.

When dust storms transport them into inhabited regions, they may eventually pose a risk to public health since they can harm the lungs when breathed and aggravate other respiratory conditions.

The figure below, created using information from the Copernicus Sentinel-5P satellite from 1 June to 15 July 2022, depicts the average aerosol concentrations close to the open sections of the lake bottom.

The lake's diminished capacity to replenish itself with water is another cause causing its water levels to decline. Every year, water from the streams that feed the lake is diverted to surrounding residential areas and agricultural, making it difficult for the lake to replenish the water it loses to evaporation.

Another factor contributing to the Great Salt Lake's desertification is the rise in water demand brought on by the expanding population of the Salt Lake City metropolitan area. Utah is expected to grow by approximately 50% by 2060, making it the US state with the highest rate of growth.

The figure below highlights Salt Lake City's urban growth between 1985 and 2019 using information from the World Settlement Footprint.

The World Settlement Footprint is the most complete dataset on human habitation ever produced, and it was developed to enhance knowledge of current patterns in urbanization worldwide. The German Aerospace Center (DLR) and the Google Earth Engine team are working together on a cooperative project called The World Settlement Footprint.