Understanding the interactions of ecology and hydrology is essential for promoting effective watershed-based river management. This paper considers the influences of watershed-level landscape development on aquatic ecosystems within stream networks by using metrics of ecological connectivity and hydrologic condition. As landscape development shifts from downstream to upstream watershed locations, aquatic communities throughout the network will be affected by potential contaminant and sediment loading and changes in upstream source communities that are affected by landscape change. Although hydrologic effects propagate in the downstream direction, not all ecological effects are dependent on upstream to downstream mechanisms. Downstream to upstream processes are important in aquatic community maintenance and are critical concerns of a comprehensive management strategy. This research develops a model of species dispersion in a theoretical stream network based on fish movement potentials and associated hydrologic dispersion mechanisms. Management strategies can be modified to minimize adverse effects on aquatic communities. This is achieved by understanding mechanisms of community response to watershed-scale landscape change along with the corresponding hydrologic changes at different points in the network. The use of this approach will promote understanding of the links between physical and ecological processes in ways that contribute to improved watershed management in human-dominated areas. Copyright ASCE 2005.