Great Salt Lake

Antelope Island at Great Salt Lake. Image by Annica Beckman from Pixabay

The Great Salt Lake is the largest saline lake in the Western Hemisphere and the eighth largest in the world. The ecology of the lake is an extraordinary example of the rich web of relationships between people, land, water, food and survival. The 15,000 square miles of various water environments, remote islands and shorelines, with 400,000 acres of wetlands, provide habitat for plants, brine shrimp, reptiles, amphibians, mammals, shorebirds and waterfowl. Birds rely on the lake, a critical link in the Pacific Flyway between North and South America. Every year 10 million birds from 338 different species come to rest, eat and breed during migrations of a thousand miles or more. With the decline of other lakes, GSL is increasingly important to these species.

Lake Levels

Due to its shallowness (an average of 14 feet deep and a maximum of 35 feet deep), the water level can fall dramatically during dry years and rise during wet years. When snowpack melts in the spring, the lake usually rises about 2 feet. In years with above-average snowpack, it can go up 3- to 4-feet. In 2021, the elevation only went up about 6 inches because of the poor snowpack.

The lake’s shallow, warm waters cause frequent, sometimes heavy lake-effect snowfall in the Wasatch Mountains, which contributes to snowpack (about 5- to 8%) and winter tourism. When the lake level is low, more lake bed is exposed, which can cause severe dust pollution. The dust carries heavy metals and chemicals into the air, which impacts air quality. At an average water level of 4,200 feet, the lake is approximately 75 miles long and 30 miles wide, with 335 miles of shoreline.

Record Low Lake Levels

The average daily value of the Great Salt Lake hit a new record low July 23, 2021 (reported July 24) when it dropped to 4191.3 as measured at the SaltAir gauge location. Lake levels continued to drop until fall storms moved in and agricultural irrigation ended for the season. Oct. 15-18, the lake’s elevation was 4190.3, a new record low. Until the extreme drought of 2021, the previous record low was set in October 1963, with an elevation of 4191.35, rounded to 4191.4 to conform with current data collection and a recorded size of 950 square miles. (In 1963, levels were measured to the hundredth. Today, they are measured to the tenth of a foot.) In 1986, the surface area was at the historic high of 3,300 square miles and an elevation of 4,211.65. USGS keeps records of the lake dating back to 1847 when the pioneers first settled in Utah.

Geography & Infrastructure

The geography of the lake combined with infrastructure has created a diversity of lake environments varying from the extremely salty North Arm (almost 28%) to the less salty South Arm (fluctuating between 6 and 27%). The Lucin Cutoff is a railroad line that runs across the lake, crossing the southern end of the Promontory Peninsula. The mostly solid causeway supporting the railway divides the lake into three arms: the northeast, northwest, and southern. The causeway obstructs the normal mixing of the lake’s waters because no major streams flow directly into the northwest arm, making it substantially saltier than the rest of the lake. This saltier environment promotes different types of algae than those growing in the southern part of the lake, leading to a marked color difference on the two sides of the causeway.

A causeway to Antelope Island in Davis County crosses the Great Salt Lake. Image by Angie Oliver from Pixabay

Economic Benefit

The Jordan, Weber, and Bear rivers flow into the lake and deposit a few million tons of dissolved solids (salts and minerals) in the lake each year. The economic output of GSL is $1.32 billion annually, with a total labor income of $375.1 million and total employment of 7,706 jobs. The industries that operate on the lake contribute significantly to the world supply of magnesium, sulfate of potash, and brine shrimp. Mining companies extract nearly 2 million tons of minerals per year. Water is removed from diked ponds by evaporation. There are over 85,000 acres of diked evaporation ponds in the Great Salt Lake – comprising an area twice that of San Francisco.

Additional Resources