DUGWAY PROVING GROUND: THE TIME WHEN A TEST KILLED 6,000 SHEEP
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During the tense years of the Vietnam War, there was a place in the U.S. where the Army conducted several highly classified weapon tests. It was in the Utah desert, specifically the Dugway Proving Ground (DPG). There were no enemies, and it was far from any active battlefield.
One day, roughly 6,000 sheep were found deceased on nearby ranchland. Who could’ve caused it? Was it the Army? Was it the tests? Was it an enemy? No one knew the cause at first. But soon after, the Army learned that a small mistake had led to a massive, tragic consequence.
What Is the Dugway Proving Ground?
The Dugway Proving Ground is a massive testing site established in 1942 by the Army in Utah’s West Desert, about 85 miles southwest of Salt Lake City. The government chose Utah because the area was isolated, a necessity given the high global tensions following World War II.
Surrounded by mountains, the testing site had very few residents living nearby. For the Army, it was the perfect place to test dangerous materials without risking civilian lives.
By the 1960s, the DPG had become a primary hub for testing chemical and biological agents. Scientists and the military used it to study how lethal substances behaved after being released into the open air. The tests were strictly classified, and the civilians living nearby had no idea what was being dropped from the sky.
Despite being a restricted military area, Dugway was still part of a natural environment. Because of the surrounding mountains, the wind was highly unpredictable. Once something was released into the open air, the military was at the mercy of the weather.
The March 1968 Open-Air VX Nerve Agent Tests
On March 13, 1968, the Army was conducting a series of massive open-air tests at the site. These operations involved everything you might expect in real combat scenarios.
The military conducted three separate tests that day: the firing of a chemical artillery shell, the burning of VX agent in an open pit, and an aerial drop. It was the third test that would cause a disaster. VX nerve agent, one of the most toxic synthetic chemicals ever developed, was released over a designated area.
If inhaled or absorbed through the skin, VX shuts down the nervous system, causing uncontrollable muscle contractions. The victim loses the ability to breathe, and death follows rapidly.
During the aerial test, an F-4 Phantom aircraft was carrying two TMU-28/B spray tanks containing a total of 320 gallons of VX. Their mission was to release the agent over a target area 27 miles west of Skull Valley. The jet completed its run, but a malfunctioning nozzle prevented one of the tanks from emptying completely.
As the aircraft gained altitude to return to base, the remaining VX agent leaked from the tank. High above the drop zone, the unpredictable wind caught the lethal chemical and carried it northeast, directly toward civilian ranchlands.
The Skull Valley Sheep Kill
The VX agent reached Skull Valley, and before the Army even realized what had happened, local ranchers noticed something was terribly wrong. Just days before, the flocks had been perfectly healthy. Suddenly, animals were dropping dead by the thousands, prompting Tooele County Sheriff Fay Gillette to visit the valley.
"It was like a movie version of 'death and destruction' — you know, like after the bomb goes off," Gillette later recalled. "Sheep are lying all over. All of them down — patches of white as far as you could see."
The animals that were still alive were showing severe distress. Their heads were tilted, their muscles were twitching, and they walked in a stilted, uncoordinated manner before suffocating. In total, more than 6,000 sheep died. The behavioral pattern the sheep exhibited was completely consistent with VX nerve agent exposure.
Shortly thereafter, scientists from the National Communicable Disease Center in Atlanta collected water, grass, blood, and liver tissue samples from the Skull Valley area. They found that the compounds recovered were identical to the Army-supplied VX.
Did the Army Take Responsibility for the Dugway Incident?
During the immediate aftermath, the Army refused to accept accountability. Dugway officials initially denied conducting chemical weapons testing in the days prior, claiming their operations had no relevance to the massive sheep die-off.
As public attention grew and ranchers demanded answers, congressional hearings and investigations followed. While the Army publicly declined to admit formal legal negligence, a later-declassified 1970 internal report called the evidence linking Dugway’s VX to the dead sheep "incontrovertible." Quietly, the military paid the primary ranchers an out-of-court settlement of over $376,000 and helped bulldoze the carcasses.
Today, the Dugway Proving Ground sheep incident remains a powerful, haunting example of the profound risks associated with chemical weapons. There was no battle, no warning for the civilians, and no second chances for the livestock. It made one undeniable truth clear: there is no such thing as a "small mistake" when dealing with weapons of mass destruction.
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BY ALLISON KIRSCHBAUM
Veteran, Military History & Culture Writer at VeteranLife
Navy Veteran
Allison Kirschbaum is a Navy Veteran and an experienced historian. She has seven years of experience creating compelling digital content across diverse industries, including Military, Defense, History, SaaS, MarTech, FinTech, financial services, insurance, and manufacturing. She brings this expertis...
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Allison Kirschbaum is a Navy Veteran and an experienced historian. She has seven years of experience creating compelling digital content across diverse industries, including Military, Defense, History, SaaS, MarTech, FinTech, financial services, insurance, and manufacturing. She brings this expertis...
