A unique interpretation key emphasizing the environmental aspects of the petroleum industry was developed as an integral part of an aerial surveillance spill prevention system. The petroleum refinery key is a unique collection of aerial and ground photographs and textual information organized to expedite the location and identification of spill threats through the use of conventional and aerial multiband photographs. The addition of aerial multiband photographs, spill threat analyses, spectral and chemical analyses of spilled materials distinguish this key from standard military interpretation keys. Throughout the aerial spill detection key, the material descriptively related oil refinery features to potential contamination of natural water resources. In addition to serving as a reference manual for imagery interpreters, they key can aid in training imagery interpreters to recognize refinery facilities, equipment, processes and associated spill threats. The key, while prepared for petroleum refineries, can serve as a model for other industries for which imagery interpretation keys are desired.