Naturally occuring nitrates killed 71 wild horses on Nellis

The nitrates that caused the deaths of 71 wild horses last summer north of Las Vegas came from natural causes, the Bureau of Land Management said today.

The horses were found around a shallow pond of water on the Air Force's Nellis Test and Training Range in June.

According to a study conducted by the Desert Research Institute, nitrate concentrations soared because of evaporation and because of animal waste and natural nitrogen deposited in soils from the. The study concluded high nitrates led to the horses' deaths.

In July 2007 initial test results found high levels of nitrates in samples taken from water in the shallow pond and from blood serum and eye fluid taken from dead horses. The results indicated nitrate levels more than 3,000 parts per million.

Las Vegas Sun