Abstract: At approximately 4:00 a.m. on March 20, 1991, a Southern Pacific freight train was traveling the track located along the coast at the perimeter of Vandenberg AFB. Approximately 6 to 8 in. of rain in the mountains nearby accumulated in a dry creek bed. As a 12 ft high wall of water struck the culvert that supported the train tracks, the culvert was mostly washed away, leaving the rails dangling across the area of the culvert. Consequently, as the train proceeded to cross, the rails spread and caused a derailment. No employees were injured and, although the train was carrying tank cars with naphtha, no appreciable amount spilled.