The State of Colorado is developing a water resources Decision Support System for the South Platte basin in northeastern Colorado. The groundwater component includes development of a MODFLOW model of the aquifer system to assist Colorado in managing this important resource. As part of this effort, a data-centered process is being implemented to allow the rapid development and modification of the model as data and needs evolve. The data-centered approach to groundwater modeling defines processes and tools that facilitate a linkage between data sources, conceptual model elements and a numerical groundwater model. This approach streamlines the modeling process when underlying data sets are expanded, simulation periods or discretization are changed, or other modifications need to be incorporated. Data being utilized in the modeling effort will reside in a data repository that is updated as information is collected by the State. These data include both the physical data on aquifer properties and configuration, and the water-rights records on diversions, consumptive use and return flows. Tools and processes will be implemented to link these data with conceptual model information to assist in formulating numerical models. These tools include geoprocessing within commercial GIS and model graphical user interface programs, and other programs to manage the water-rights information used in the model.