Utah’s Bonneville Salt Flats are an iconic setting for car commercials and feature films. Land speed records have been made and broken on its lunarlike surface for more than a century. Now the sprawling salt pan, about 185 kilometers west of Salt Lake City, is in trouble.
This year its normally rock-hard crust looked like gray, gritty soup. Without a firm track, organizers were forced to cancel Bonneville Speed Week, a major racing tournament, for the second consecutive year. The unwelcome decision put the 115-square-kilometer salt flats’ vulnerability in sharp relief. A large potash mine, just across Interstate 80 and south of the raceway, has drawn brine away from the aquifer under the salt flat for decades. Extreme storms, like last winter’s heavier-than-usual rains, have swept in from the surrounding watershed and dissolved the hard, salty surface into a muddy slush. The 20-kilometer-long racetrack has crumbled to 12 kilometers and the central basin, where salt is thickest, has degraded from a depth of 1.5 meters to 30 centimeters. The alarming signs have convinced the government, the mining company and the racing community to take action. “We’re measuring [the surface] in inches now,” says Stuart Gosswein, a spokesman for Save The Salt, a coalition of racing companies and fans.
The flats formed 17,000 years ago as a vast saline lake. As the water evaporated over millennia, a thick layer of salt remained on the lakebed. Today the crust is replenished naturally by winter rains, which carry minerals—including potash and halite (aka rock salt)—from the watershed. This brine floods the surface of the ancient basin and collects in a shallow aquifer. During the summer dry season the brine evaporates and its minerals percolate up to the surface, adding to the crust’s mass.
At least it is supposed to work that way. For the past five decades a succession of companies has held the license to operate the big mine across the highway. The mine extracts brine from the salt flat and surrounding land and feeds it into giant ponds. When the liquid evaporates, it leaves behind potash, a potassium-based mineral used in fertilizer, and salt.
In the 1990s the U.S. Bureau of Land Management (BLM), which manages the Bonneville Salt Flats as a Special Recreation Management Area and issues mining permits, realized that more salt was being taken out by the mine than was being replenished by nature—about 45 million to 70 million metric tons in all, says Kevin Oliver, the BLM’s West Desert District manager.
That discovery prompted an unusually amicable collaboration between the mine’s current owner, Intrepid Potash, the BLM, researchers at the University of Utah and the racing community to stanch the flow. In 1997 the company agreed to pay for a program to pump its excess salt back onto the flats. Intrepid adds water to the leftover salt and then floods the flats with millions of gallons of the solution, which yielded more than 450,000 metric tons of salt last winter. Intrepid spokesperson Gary Kohn estimates that the company has returned at least 4.5 million metric tons over the past 15 years. “We want to be good stewards of the environment, and we want to help understand what’s going on,” Kohn says.
The pumping program has stabilized the situation but it hasn’t rebuilt much mass, Gosswein says. To step up the process the group has worked with the BLM to experiment with laying down dry salt in specific areas, but the heavy rains last winter foiled their success. Another solution, he says, could be building walls around the racetrack to keep the replenished brine in and salt-dissolving storm water out.
The BLM and Intrepid are required by law to evaluate the salt’s long-term condition every 15 years. Brenda Bowen, a geophysicist at the University of Utah, is leading the current three-year study to determine whether the salt itself has altered since the last assessment in 2003, and if so, why. Previous sampling involved drilling a corkscrewlike augur into the crust to measure only the salt’s thickness. Bowen’s team will extract complex cores from 70 sites scattered around the flats, allowing analysis of its chemistry, microbes and balance of water to minerals: clues to what is currently driving the salt’s changes. “Is it climate change; is it racing, is it mining? It’s probably all of those things,” Bowen says.
What Bowen discovers will guide the preservation of the flats for years to come, and could have an impact on the management of similar sites. Bolivia’s Uyuni Salt Flats—the largest in the world—are thought to hold 50 percent of the world’s lithium, a lightweight element used in rechargeable batteries. Salt pans in Argentina and Chile complete South America’s “lithium triangle,” a locus of interest for mining companies and electronics manufacturers. “We’ll be looking at how much can you poke and perturb a place before it reaches a new equilibrium” and the natural system changes irrevocably, Bowen says.
The Bonneville Salt Flats “are really special to a lot of people. It’s a beautiful and unique place,” Oliver says. Although Speed Week was put on hold this summer, racing fans expect fall tournaments to be held as scheduled—conditions permitting. But how long business as usual can go on remains unclear.