The Great Plains Coal Gasification Plant (GPGP) is the first commercial coal-to-synthetic natural gas plant constructed and operated in the United States. This process stream design data report provides non-proprietary information to the public on the major GPGP process streams. The report includes a simplified plant process block flow diagram, process input/output diagrams, and stream design data sheets for 161 major GPGP process and effluent streams. This stream design data provides an important base for evaluation of plant and process performance and for verification of the Department of Energy's ASPEN (Advanced System for Process Engineering) computer simulation models of the GPGP processes. 8 refs., 22 figs., 2 tabs.