Dugway Proving Ground, about 85 miles southwest of Salt Lake City, is an Army facility established in 1942 to test biological and chemical weapons. It’s just south of the Utah Test and Training Range, together forming the largest overland special use airspace in the United States.

In 1968, 6,249 sheep in Skull Valley were poisoned with an organophosphate. This coincided with several open-air tests of the nerve agent VX at Dugway, thirty miles away from Skull Valley. The Army initially denied that nerve gas killed the sheep, blaming crop pesticides, but veterinary autopsies of the sheep definitively identified the presence of VX.

While the Army never admitted liability for the “Dugway sheep incident,” they did pay ranchers for their losses. On the official record, the claim was for 4,372 “disabled” sheep, of which about 2,150 were either killed outright by the VX, or were so critically injured that were euthanized. Another 1,877 exposed sheep were either “temporarily” injured or showed no signs of injury. They were all eventually euthanized by the ranchers, since even the potential for exposure to nerve gas had rendered them permanently unsalable for meat or wool.

In 2015, it was revealed that Dugway had sipped potentially live anthrax to more than 184 government and commercial labs over a decade. They’re looking in to it.

Some have called nearby Michael Army Airfield the “new Area 51” for secret aircraft testing, with Dugway Proving Ground serving as a buffer zone, as the Nevada Test Site served for Groom Lake.