Environmental impact studies are costly and time-consuming and involve the collection, review, and analysis of large volumes of information by experts. Conventional EIS/EIR approaches do not typically integrate information and knowledge in a practically applicable form. A unique, ArcView GIS-enabled expert system is being used by land managers, natural resource managers, and project developers to address this shortcoming. The system captures multidisciplinary expert knowledge, comprehensively predicts impacts, documents each analysis, pinpoints information deficiencies, rapidly facilitates "what-if" evaluation of alternatives, recommends mitigation and monitoring actions, and creates a range of text- and map-based reports. Once a given assessment is complete, the system is ready for use as an in-house environmental management decision support system.