The Great Salt Lake, or the “Bad Water,” as it was known to the Shoshoni, exists thanks to climate change.

The present lake was formed from a much larger lake, Lake Bonneville, about 30,000 years ago. A drier climate reduced Lake Bonneville to the Great Salt Lake’s current dimensions. The lake has persisted within its historical size range for nearly 13,000 years. Records show the lake was largest in 1985 at 8,500 square kilometers, and then shrank to 2,500 square kilometers in 2021, only 40 years later.

The evaporation of the lake seemed imminent just last year. Such concerns can change quickly.

Up to 1985, rapid lake growth resulted in flooding. At that time, as older residents of Utah will remember, the West Desert Pumping Project diverted nearly a cubic mile of water into a depression to the west to prevent flooding of farms to the east of the lake. The pumping stopped in 1989 as inflows from the Bear River and smaller rivers again declined. The pumps are in place still, just in case.

Changes in climate over thousands of years reduced the depth of Lake Bonneville from nearly 1,000 feet to today’s average of only 16 feet for the Great Salt Lake. The lake still contains nearly 4.6 cubic miles of water. The Great Salt Lake is a terminal lake — that is, water flows in, but does not flow out. Lake Bonneville did drain to the Snake River, at times, before 13,000 years ago. Since then, as a terminal lake, the lake exists due to a balance between inflow from rainfall and rivers competing with evaporation by the sun.

A simple calculation shows that the sun heating the Great Salt Lake could evaporate all its water in a year, leaving only salt pans and saline puddles behind. For millennia, the lake has been constantly replenished by inflow, but the inflow is changing as humans increasingly divert water for other purposes.

Today, as much as two-thirds of the potential river inflow never reaches the lake. Consequently, the lake is shrinking. However, it is not climate change, but human water use that’s cutting the Great Salt Lake’s lifeline. Humans take the water and then mutter something about “climate change,” hoping that no one will notice what they’re doing to Utah’s most famous natural symbol.

Manicured green lawns consume vast amounts of water, not to mention fertilizers and pesticides. The proposed Bear River Development Project would take 30% of the average Bear River water flow, mostly to water lawns. Thirty percent of the average Bear River water flow amounts to 100% in dry years. Then, the lake would shrink or even vanish.

A perfect green lawn, once a symbol of suburban bliss, is seen increasingly as an environmental threat, not just in semi-arid regions like Utah, but all over America. For Utahns determined to have a green lawn, “gray water” — waste water from individual homes— could be a way to keep their lawns green. That was the solution at Pebble Beach Golf where perfect greens trumped imperfect water. A better solution is to dispense with the perfect green lawn entirely, substituting native plants, which are beautiful as well as commensurate with the local environment.

Let’s take a closer look at the long-term history of the water level in the Great Salt Lake. Hydrologists have reconstructed the level of the lake over the past 600 years. The level changes constantly, but the average remains close to 4,202 feet above sea level. Utah’s geology agency data shows the same variations for more than 180 years. The ups and downs closely correlate with rainfall changes. If rainfall is high, the lake rises, and if low, the lake level sinks, just as one expects for a lake in close equilibrium with the climate. If human-originated climate change were altering the lake, the average would decline (or rise), but nothing remarkable is found during the entire industrial age, from 1800 to today. Climate change, clearly, is not the main threat to the lake.

Opinion: Making the Great Salt Lake into a national park
What is the Spiral Jetty without the Great Salt Lake?

The Great Salt Lake has important environmental, ecological and dollar values. The lake is responsible for a local “lake effect precipitation” — typically 10% of the average 16 inches a year is provided to areas toward the east. The semi-arid Great Salt Lake region has highly variable annual rainfall. The year 1979 was the driest year on record with 8.70 inches of measured rainfall, while only four years later, 1983 was the wettest year on record, with 24.26 inches.

The large variation in annual rainfall is due to weather, not climate change. The “average” Great Salt Lake level has been nearly constant over hundreds of years. The rapid variation in area results from evaporation and water diversion in the shallow lake.

The Great Salt Lake is a major tourist attraction for water sports, for viewing migratory birds and for enjoying the spectacular Utah scenery in quiet contemplation. If the Great Salt Lake is strangled by water diversion, its benefits — and a part of the soul of Utah — disappear. The Great Salt Lake wetlands are, biologically, highly productive sites and a critical wildlife habitat. The lake’s wetlands are essential resting and feeding sites for migratory birds. The rapidly expanding wind turbine “farms” on the Great Plains are directly in the paths of migratory birds, increasingly slaughtering them. Eliminating the migratory bird habitats could easily be a coup de grâce for those beautiful birds.

“Climate change” is blamed for lots of things, but water diversion is the greatest threat to the Great Salt Lake. Utahns should oppose water diversion for real estate development, and work to maintain natural water flows into the lake. The lake will still fluctuate, but as for thousands of years, it will not disappear. 

Decisions affecting Utah’s land and natural resources should be made by Utahns, not by unelected bureaucrats in the federal government or real estate developers. Utah needs to take back control of its land, as Eastern states have already done, and then do what’s best for Utah, and for its beautiful resource, the Great Salt Lake.

William Hayden Smith holds a doctorate in chemistry from Princeton University and is now a professor of earth and planetary sciences at Washington University in St. Louis, Missouri. His most recent work is at the interface of climate and energy and can be seen at