On March 14, 1968, sheep grazing in Skull Valley began to act strangely. They stumbled, convulsed and collapsed. By sunset, thousands of sheep were dead or dying, and within days more than 6,400 sheep were dead. Sheep herders and veterinarians were mystified.
On March 20th, a toxicologist from the National Animal Disease Center arrived. He concluded that the sheep had died from a poison that had affected their nervous systems. The Army facility Dugway Proving Ground, which regularly conducted spray tests of the nerve agent VX, was only 20-30 miles from the grazing grounds. The Army denied any involvement in the matter.
On March 21st, Senator Frank Moss released a document that he had received from the Army. It stated that the Army had dispersed 320 gallons of “non-persistent” gas from an airplane on March 13th, as part of a spray test. The Army cancelled all spray testing at Dugway, but continued to deny that the nerve agent (called VX) could have caused the sheep deaths.
Governor Calvin L. Rampton became involved, placing calls to Washington and publicly stating that he believed that Dugway’s testing of VX caused the death of the sheep, and that the federal government should reimburse ranchers for their losses.
On March 25th, the Army publicly conceded that its testing may have led to the death of the sheep. On April 12th, the Public Health Service released a report verifying that the sheep died due to exposure from large amounts of a substance with identical properties to VX nerve agent. The ranchers sent a claim for $376,685 to cover their losses, and the Army paid the claim.
There’s still controversy over the death of the sheep in Skull Valley. While the Army paid the ranchers’ claim, it still denied that VX nerve agent conclusively caused the deaths. Pesticide sprayed in the area may have had a role in the incident; others have several conspiracy theories about the matter.