Aspen prepared a Preliminary Draft EA (May 1997) to evaluate the potential environmental impacts that may result from the US Army's proposed action of acquiring the airspace above the Silurian Valley, northeast of Barstow, California. The proposed action would convert a portion of three existing military operations areas (MOAs) (Panamint, Shoshone, Silver MOAs) into fully restricted airspace areas (proposed as R-2502A, R-2502B, and R- 2502C) controlled by the National Training Center (NTC).