Source-water protection area (SWPAs) were delineated eight years ago for production wells in a buried outwash valley in southwest Ohio using a steady-state MODFLOW simulation of groundwater flow and MODPATH for particle-tracking. A detailed uncertainty analysis was conducted at that time. The goal of this study is to use the same basic model to develop a transient simulation of the same system using recently collected data. The original steady-state model was calibrated to a set of hydraulic heads measured throughout the basin during a period of low-flow conditions and assumed to represent long-term average conditions. The calibrated model was used for delineation of source water protection area and for Well 1, the one year time-of-travel SWPA is 89.6 ha, for the five years time-of -travel SWPA is 220 ha and for Well 3, 33.9 and 44.1 ha, respectively. The updated model will be calibrated to a new set of hydraulic heads during low-flow conditions as well as temporally-variable heads during a variety of conditions. After calibrating the model to transient data, the SWPA will be re-delineated and compared with the original delineations. By performing this model verification, we will assess the importance in this case of developing the more complex transient model. We expect that the transient calibration will help to decrease the large uncertainty associated with SWPA delineations.