The exposed, encrusted bed of the depleted Great Salt Lake stretches for miles and miles, merging with Utah’s West Desert somewhere off in a distance defined by mountain ridgelines rising above the horizon like jagged clouds.
Few know this rarely visited terrain better than Kevin Perry, an atmospheric sciences professor with the University of Utah who spent more than 125 days pedaling 2,300 miles of playa on a one-man data-gathering mission. His goal was to characterize the potential for the dry lakebed to release dust pollution over the Salt Lake City metro area, but he encountered things that utterly surprised him, including two bullet rounds shot at him.
The dry lakebed, 757 square miles of it exposed after decades of upstream water diversions and drought, is hardly the featureless, uniform expanse of sand most people envision. Instead, it is highly varied, embedded with curious objects, like jettisoned pieces of military aircraft, relic automobiles, a crane, tractors, anchors, shipwrecks, wildlife, even rocks that had moved by themselves, leaving mysterious tracks. But sadly he found no meteorites, something he was actually looking out for.
“This was essentially a fishing expedition,” Perry said last week in his office. “Nobody else was ever going to do this. It gives a
definitive answer of what’s out there. Then there’s no doubt about it. If it was out there, I would have seen it.”
Using a mountain bike pulling a trailer, Perry collected soil samples and recorded observations at 5,246 sites, each separated by 500 meters. His research team used the data to identify the playa’s “hot spots” likely to release dust when winds exceed 25 mph and areas where heavy metals have accumulated.
Salty accumulations were so hard on his equipment, Perry went through three bikes. He chose to personally gather all the data by bicycle to reduce costs, but, more importantly, to avoid breaking up the playa’s surface. He saw the damage all-terrain vehicles can do.
“It’s the crust that protects the lakebed from wind erosion,” he said. “I figured if I’m going everywhere [on the lakebed], the last thing I want to do is harm the thing I’m trying to study.”
Crust to dust
He found that 9% of the lakebed — still a vast 43,600 acres — is silty enough to put the dust known as PM10 in the air, according to the 319-page report Perry submitted to the Utah Department of Natural Resources with colleagues Erik Crosman and Sebastian Hoch.
DNR sponsored the study along with the Department of Facilities Construction and Management, which is participating as part of its assessment of the Utah State Prison’s future site near the lake’s southeast shore.
The study concluded 73% of the playa is protected with a crust that keeps the soils in place, and another 15% is vegetated, some of it invasive phragmites. These findings point to the need of protecting the lakebed from motorized use.
“I was surprised how much of it was actually covered by physical crust,” said Perry’s U. colleague Jim Steenburgh, who is not involved with the research. “That’s a good thing. It would be very bad if we, being humans, went out there and beat up that crust. Those dust sources would go up a lot.”
Previous research led by Utah State University found that diversions in the Bear, Jordan and Weber watersheds have lowered the level of the Great Salt Lake’s surface by 11 feet. Studies attributed 63% of these diversions — now totaling 1.4 million acre-feet a year — to agriculture, 13% to evaporative mineral extraction and 11% for municipal uses.
Perry and other scientists believe that historic lake levels will never be restored unless more water is allowed to reach the lake, yet future diversions totaling hundreds of thousands of acre-feet are proposed for the Bear River.
The disappearance of saline terminal lakes is a problem around the world, wherever diversions are preventing rivers from replenishing bodies such as California’s Mono and Owens Lake, Iran’s Lake Urmia and Israel’s Dead Sea.
If Utah keeps diverting more and more of the Great Salt Lake’s tributaries, the lake will continue shrinking, according to biologist Bonnie Baxter, who heads Westminster College’s Great Salt Lake Institute.
“The number of acres [of exposed lakebed] are going to get larger. The number of problem sites are likely to increase and maybe even other problem sites appear because of less groundwater,” said Baxter, who co-edited the forthcoming book “Great Salt Lake Biology: A Terminal Lake in a Time of Change.” “There are a lot of springs around the margins of the lake. But those are disappearing. So maybe this site isn’t a significant air-quality problem now, but that could change.”
As the lake becomes more depleted, she said, the exposed playa will pose a greater threat to Utah’s air quality and put more dust on the Wasatch Mountains’ snowpack, making it melt sooner, potentially disrupting water supplies and adding to the ecological decline of the lake.
“Since white people came into the valley [in the 1840s], we have a history of dumping into the lake. All that is going to become airborne,” Baxter said. “The heavy metals that are there and other pollutants are likely going to be a piece of that dust storm.”
Blowin’ in the wind
Perry’s sampling regimen equated to one observation point per 92 acres of lakebed, with sampling locations separated by 500 meters in a massive grid. At each site, he recorded visual observations, took three soil samples — two from the surface and the other from under the crust — and assessed the sites’ potential for generating wind-borne dust.
He collected nearly 16,000 soil samples weighing at least four tons.
His research team consolidated these samples into 122 batches, each representing 16 square kilometers of dry lakebed, then analyzed them for 53 elements. The team found troubling concentrations of nine heavy metals, including arsenic, cobalt, antimony, lithium, manganese, vanadium and zirconium, copper and lanthanum. High concentrations of these and other metals occurred in areas associated with discharges connected with industry, wastewater treatment and agriculture.
For example, high levels of copper were found near Kennecott Utah Copper’s smelting operations. Phosphorus was concentrated near the Utah Test and Training Range and in Bear River Bay. Perry suspects the phosphorus is associated with military munitions dropped near the lake’s southwest shore and with fertilizer-laden runoff entering the lake from the Bear and Weber rivers.
His study produced numerous maps of the lakebed showing the zones with elevated metals. Where these zones overlap with “hot spots” for wind erosion is where officials should do careful monitoring in the future.
“The entire lakebed is not blowing; only a small part of it is,” Perry said. “So when we do future dust research, we can go out to those specific areas and monitor them over time.”
While Perry brought back a priceless data trove, he also returned with lots of artifacts.
Among the souvenirs are a weather balloon, coyote skulls and a patent medicine bottle, which he determined predated 1906 because it had the word “cure” on the label. Regulators banned questionable claims like “cures” from the marketing of patent medicine, aka snake oil, after 1906.
He also dug up the two bullets fired toward him during hunting season when he was working in a remote corner of the lake’s northern edge. He’ll never forget the sound of the bullets slicing through the air.
“All of a sudden I hear a bullet hit about 20 yards off to my right. And I’m like, ‘What the heck was that?’ And then I heard one whiz past in the air,” he said. “I hit the deck and just waited, hoping that they would stop shooting at me. At this point, I was a mile and a half away from where anybody would be.”
He located the spots where the rounds hit the lakebed and extracted the bullets.
“I brought them back and one of my military folks took a look at them and they said, ‘Those are from an AR-15 rifle,’” he said. “After that, I was wearing hunter’s orange the entire time I was out there.”
He also gathered every mylar party balloon he found, and there were many, but those went in the trash.
The weirdest things he encountered, he left untouched: isolated rocks lying on the crust, followed by a track indicating inexplicable movement across the playa. But how can a rock move by itself? Perry has no idea, but he hopes to go back and gather the data that will explain the phenomenon, which has been observed on playas elsewhere.
“There’s a theory on how they move in Death Valley,” he said. “But I don’t think that is going to work out here on our Great Salt Lake because it involves a lot of ice.”