Nitrate that killed wild horses was from natural sources

Nitrate poisoning that killed 71 wild horses last year at Cactus Flat on the Tonopah Test Range in central Nevada came from natural sources and not remnants of aircraft de-icing fluids as former workers at an airfield at the range had suspected, Bureau of Land Management officials said today.

In a statement, BLM officials from the Las Vegas Field Office cited a long-awaited report by the Desert Research Institute. The institute's investigation found that high levels of nitrates in water the horses drank near Cactus Flat were from "a combination of evaporative concentration and animal waste and natural soil nitrogen" deposited from the air.

The carcasses of 71 wild horses were found in June 2007 on the Nevada Wild Horse Range, which is within the sprawling Nellis Air Force Range.