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Dead sheep owned by Ray Peck in Skull Valley, 1968[1]

The Dugway sheep incident, also known as the Skull Valley sheep kill, was a 1968 sheep kill that has been connected to United States Army chemical and biological warfare programs at Dugway Proving Ground in Utah. Six thousand sheep were killed on ranches near the base, and the popular explanation blamed Army testing of chemical weapons for the incident, though alternative explanations have been offered. A report, commissioned by Air Force Press Officer Jesse Stay and first made public in 1998, was called the "first documented admission" from the Army that a nerve agent killed the sheep at Skull Valley.


Since its founding in 1941, much of the activity at Dugway Proving Ground is a closely guarded secret. Activities at Dugway included aerial nerve agent testing. According to reports from New Scientist, Dugway was still producing small quantities of anthrax as late as 1998, 30 years after the United States renounced biological weapons.[2] There were at least 1,100 other chemical tests at Dugway during the time period of the Dugway sheep incident. In total, almost 500,000 lb (230,000 kg) of nerve agent were dispersed during open-air tests. There were also tests at Dugway with other weapons of mass destruction, including 328 open-air tests of biological weapons, 74 dirty bomb tests, and eight furnace heatings of nuclear material under open air conditions to simulate the dispersal of fallout in the case of meltdown of aeronautic nuclear reactors.


In the days preceding the Dugway sheep incident the United States Army at Dugway Proving Ground conducted at least three separate operations involving nerve agents. All three operations occurred on March 13, 1968. One involved the test firing of a chemical artillery shell, another the burning of 160 U.S. gallons (600 L) of nerve agent in an open air pit and in the third a jet aircraft sprayed nerve agent in a target area about 27 mi (43 km) west of Skull Valley. It is the third event that is usually connected to the Skull Valley sheep kill.

The incident log at Dugway Proving Ground indicated that the sheep incident began with a phone call on March 17, 1968 at 12:30 a.m. The director of the University of Utah's ecological and epidemiological contract with Dugway, a Dr. Bode, phoned Keith Smart, the chief of the ecology and epidemiology branch at Dugway to report that 3,000 sheep were dead in the Skull Valley area. The initial report of the incident came to Bode from the manager of a Skull Valley livestock company.[3] The sheep were grazing in an area about 27 mi (43 km) from the proving ground; total sheep deaths of 6,000-6,400 were reported over the next several days as a result of the incident.[4] The Dugway Safety Office's attempt to count the dead sheep compiled a total of 3,843.[5]

Possible causes

Previously obtained documents said one such demonstration also occurred the day before the mysterious sheep deaths in 1968.[6] On 13 March 1968, an F-4 Phantom strike aircraft flew a test mission over the Dugway Proving Ground with chemical dispensers containing VX. One of the dispensers was not completely emptied during the test, and as the F-4 gained altitude after its bombing run, VX trickled out in a trail behind the aircraft, drifted into Skull Valley, north of the proving ground, and settled over a huge flock of sheep.[7]

One explanation in the aftermath of the incident was that a chemical or biological agent had escaped from the Dugway Proving Ground. Circumstantial evidence seemed to support this assertion, the United States Army admitted to conducting open-air tests with the nerve agent VX in the days preceding the sheep kill.[3] The Army intimated that a spray nozzle had malfunctioned during the test causing an aircraft to continue spraying VX as it climbed to higher altitudes.[3][4] It was reported that a small amount of VX was found in the tissue of the dead sheep.[4]

Other information contradicted the initial assumptions about the cause of the incident. One contradiction to nerve agent exposure as a cause came in the symptoms of some of the sheep following the incident.[5] Several sheep, still alive, sat unmoving on the ground. The sheep refused to eat, but exhibited normal breathing patterns and showed signs of internal hemorrhaging.[5] Regular breathing and internal hemorrhaging are inconsistent with nerve agent exposure.[5] Interesting is; "...and in fact no other animals of any type, including cows, horses, dogs, rabbits, or birds, appeared to have suffered any ill effects, a circumstance that was hard to explain if VX had in fact causes the sheep deaths."[3]


The incident had an impact on the Army, and U.S. military policy within a year. The international infamy of the incident contributed to President Richard Nixon's decision to ban all open-air chemical weapon testing in 1969. The sheep incident was one of the events which helped contribute to a rise in public sentiment against the U.S. Army Chemical Corps during and after the Vietnam War.[8] Ultimately, the Chemical Corps was almost disbanded as a result.[8]

Following the incident, the Army and other state and federal agencies compiled reports, some of which were later characterized as "studies". A report which remained classified until 1978 and unreleased to the public until nearly 30 years after the incident was called the "first documented admission" by the Army that VX killed the sheep. In 1998, Jim Woolf, reporting for The Salt Lake Tribune, made the content of the report public for the first time. The report described the evidence that nerve agent was the cause of the sheep kill as "incontrovertible." The 1970 report, compiled by researchers at the U.S. Army's Edgewood Arsenal in Maryland, stated that VX was found in both snow and grass samples recovered from the area three weeks after the sheep incident.

The report concluded that the "quantity of VX originally present was sufficient to account for the death of the sheep." Even after the report surfaced the Army maintained that it did not accept responsibility for the incident nor did they admit negligence. As late as 1997, one year before the report went public, U.S. Department of Defense officials stated that "the reason it (the report) was never published is because it wasn't particularly revealing." Lee Davidson, Correspondent for Deseret News wrote in June 1994 that Ray Peck, who owned the sheep that were killed was outside working during the May 13, 1968, incident, and members of his family developed nervous-system illnesses for years afterwards, similar to ills reported by people exposed to low levels of VX in lab experiments. Also, the probe showed that medical tests the Army had used to claim humans were not affected are now considered inconclusive, and the Pecks had shown other signs of low-level VX exposure.[6]

See also


  1. Lee Davidson and Joe Bauman (2001-02-12). "Toxic Utah: A land littered with poisons". Deseret News.,3329,250010322,00.html. Retrieved 2008-03-18. 
  2. Hambling, David. "US army plans to bulk-buy anthrax", Newἠ Scientist,September 24, 2005. Retrieved November 27, 2007.
  3. 3.0 3.1 3.2 3.3 Regis, Edward. The Biology of Doom: The History of America's Secret Germ Warfare Project, (Google Books), Owl Books, 2000, p. 209, (ISBN 080505765X). Retrieved October 10, 2008.
  4. 4.0 4.1 4.2 Hoeber, Amoretta M. and Douglass, Jr. Joseph D. "The Neglected Threat of Chemical Warfare", (JSTOR), International Security, Vol. 3, No. 1. (Summer, 1978), pp. 55-82. Retrieved November 26, 2007.
  5. 5.0 5.1 5.2 5.3 Mauroni, Albert J. America's Struggle with Chemical-Biological Warfare, (Google Books), Praeger, Westport, Connecticut: 2000, p. 40, (ISBN 0275967565). Retrieved November 26, 2007.
  6. 6.0 6.1 "LETHAL BREEZE" By Lee Davidson, Correspondent Deseret News Sunday, June 5, 1994 Retrieved July 2, 2012:
  7. A History Of Chemical Warfare”, Greg goebel at (Accessed on January 31, 2010
  8. 8.0 8.1 Mauroni, Al. "The US Army Chemical Corps: Past, Present, and Future", Army Historical Foundation. Retrieved October 10, 2008.

Further reading

  • Boffey, Philip M. "Nerve Gas: Dugway Accident Linked to Utah Sheep Kill", (Citation, log-in required to view article) Science December 27, 1968, Vol. 162, No. 3861, pp. 1460 – 1464. Retrieved November 26, 2007.
  • Sheep & the Army, Time Magazine, April 5, 1968, accessed October 10, 2008.
  • "Toward the Doomsday Bug", Time Magazine, September 6, 1968, accessed October 12, 2008.
  • Van Kampen, K.R., et al. "Effects of nerve gas poisoning in sheep in Skull Valley, Utah", Journal of the American Veterinary Medical Association, (Abstract), April 15, 1970; Vol. 156 Issue:8 pp. 1032–5, accessed October 10, 2008.
  • Wright, Burton. "America's Struggle With Chemical-Biological Warfare", (Book review), Army Chemical Review, February, 2001, accessed via on October 12, 2008.

External links

  • Biewin, John. Sheep Kill, (radio broadcast), NPR, February 8, 1998, accessed October 10, 2008.
  • Cianciosi, Scott. "The Sheep Incident",, March 17, 2008, accessed October 12, 2008.

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