Spatial and temporal variability in river flow regime is a fundamental driver of instream habitat structure and riverine communities. From the literature on environmental flows, more than 200 'ecologically relevant' hydrological variables have been identified. The ability of these indices to predict changes in riverine communities is highly variable. To date, despite the wide acknowledgement of the need for detailed analysis of paired hydrological and ecological series, few appropriate long-term series are available. Here, we examine the macroinvertebrate community response to inter-annual and regional flow variability. We also examine the potential redundancy among hydrological indices and explore how this can be reduced. The results highlight the response of benthic macroinvertebrate communities to periods of sustained low flow and the importance of taxonomic resolution. In addition, we consider how the classification of different river flow regimes offers a structured way to explore spatial and temporal hydroecological relationships. The results of this type of research help in the development of our understanding of hydroecological patterns and provide a baseline dataset to assess future hydroecological responses to climate change and anthropogenic modification of riverine ecosystems.