The integrated hydrology model (InHM), a physics-based hydrologic-response model with sediment-transport capabilities, was used to simulate upstream impacts from dam construction/removal for a generalized approximation of the Searsville watershed in Portola Valley, California. Four 10-year simulation scenarios (pre-dam, early dam, current and post-dam) were considered. Each scenario was simulated using the same sequence of synthetically generated rainfall and evapotranspiration. For each scenario the boundary-value problem was constructed based on the available watershed information (e.g. topography, soils, geology, reservoir bathymetry and land use). The results from the simulations are presented in terms of the temporal and spatial characteristics of hydrologic response and sediment transport. The commonalities/differences between the four Searsville-like watershed scenarios are discussed. The effort demonstrates that heuristic physics-based simulation can be a useful tool for the characterization of dam-related impacts at the watershed scale. Copyright © 2008 John Wiley & Sons, Ltd.