ABSTRACT: The Hydrological Simulation Program-FORTRAN (HSPF) describes discharge from a stream reach based on function tables (FTABLES) that relate stream stage, surface area, volume, and discharge. For this study, five FTABLE scenarios were compared to assess their effect on daily discharge rates predicted using HSPF. Four “field-based” FTABLE scenarios were developed using detailed cross section surveys collected at predefined intervals along 14 reaches in the study watershed. A fifth “digital-based” scenario was developed using digital elevation models (DEMs) and Natural Resource Conservation Service (NRCS) Regional Hydraulic Geometry Curves. The Smirnov k-sample test was used to compare average daily discharge rates simulated with HSPF using the five FTABLE scenarios. No significant difference in simulated stream discharge was found (p = 0.99) between the five FTABLE scenarios. Additional examination of the four field-based scenarios revealed that the number of cross sections per stream reach used to generate FTABLES had little effect on the resulting stage discharge relationship. These findings suggest that FTABLES generated using digital data are a viable option when simulating stream discharge with HSPF and that if field data are used to generate FTABLES, using fewer cross sections will not adversely affect simulated discharge predictions.