Food webs and river drainages are both hierarchical networks and complex adaptive systems. How does living within the second affect the first? Longitudinal gradients in productivity, disturbance regimes and habitat structure down rivers have long interested ecologists, but their effects on food web structure and dynamics are just beginning to be explored. Even less is known about how network structure per se influences river and riparian food webs and their members. We offer some preliminary observations and hypotheses about these interactions, emphasizing observations on upstream–downstream changes in food web structure and controls, and introducing some ideas and predictions about the unexplored question of food web responses to some of the network properties of river drainages.