1. Macroinvertebrate community composition was assessed in small streams of the Melbourne region to test the effects of (a) urban density (catchment imperviousness 0–51%) and (b) stormwater drainage intensity (comparing the intensively drained metropolitan area with urban areas of the hinterland, which had open drains and some localized stormwater drainage). 2. Hinterland communities separated into two groups of sites correlating strongly with patterns of electrical conductivity (EC), basalt geology and annual rainfall. Community composition varied little in the high‐EC, western group (imperviousness 0.2–1.2%), but in the eastern group it was strongly correlated with catchment imperviousness (0–12%), with lower taxon richness in more impervious catchments. 3. Metropolitan communities (imperviousness 1–51%) were all severely degraded, with high abundances of a few tolerant taxa. Community composition was poorly correlated with patterns of geology, rainfall or imperviousness. Differences between metropolitan and hinterland communities were well explained by patterns of biochemical oxygen demand and electrical conductivity, which were postulated to indicate the more efficient transport of pollutants to receiving streams by the metropolitan stormwater drainage system. 4. Degradation of macroinvertebrate community composition was well explained by urban density but intensive urban drainage increased degradation severely at even low urban densities. Quantification of relationships between imperviousness, drainage intensity and stream degradation can better inform the assessment, conservation and restoration of urban streams.

With drought and climate change leading to increased water scarcity at a time of increasing consumptive demand, the provision of environmental flows is a potentially divisive issue. Demonstrating the ecological effects of environmental flows is thus important for supporting policy and management decisions. We describe the development of a multi-basin monitoring and assessment program for environmental flows in Victoria, Australia. We examine the challenges associated with negotiating the turbulent boundary between water science and water management when building a partnership between multiple partners with differing priorities, expectations and responsibilities. We describe the mistakes made and corrective actions taken, and present a critical analysis of the lessons learned. Strong science–management collaboration will be aided by: explicit recognition of the importance of the engagement process, establishing the partnership at the outset, assessing and understanding the disparate needs of individual partners, frequent articulation of the shared vision that motivated the collaboration, and providing sufficient opportunities for information exchange among partners. Cullen first described the challenges to science-management collaboration twenty years ago, but to some extent, the same mistakes continue to be made. Our real-world example shows that it is possible to develop a strong partnership, even when such mistakes are made at the outset.

Around the world, governments are making huge investments in environmental flows. However, much of the rationale for these releases is based on expert opinion and is thus open to challenge. Empirical studies that relate ecological responses to flow restoration are mostly case studies of limited generality. Radically, different approaches are required to inform the development of general models that will allow us to predict the effects of environmental flows. Here, we describe the modelling framework being used in a major study of environmental flows in the Australian state of Victoria. The framework attempts to make best use of all the information available from the literature, experts, and monitoring data, to inform the development of general quantitative response models. It uses systematic review of the literature to develop evidence‐based conceptual models, formal expert elicitation to provide an initial quantification of model links, and data derived from purpose‐designed monitoring programs over large spatial scales. These elements come together in a Bayesian hierarchical model that quantifies the relationship between flow variation and ecological response and hence can be used to predict ecological responses to flow restoration. We illustrate the framework using the example of terrestrial vegetation encroachment into regulated river channels. Our modelling framework aims to develop general flow‐response models and can immediately be used to demonstrate the ecological return on investment from environmental flow programs. However, the framework also has the potential to be incorporated into planning and decision‐making processes, helping to drive a transformation in evidence‐based practice for environmental flow management. © 2014 The Authors. River Research and Applications published by John Wiley & Sons, Ltd.

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1. Epilithic and epiphytic diatom community composition were assessed in small streams of the Melbourne region to test the effects of (a) urban density (sub‐catchment imperviousness 0–51%) and (b) stormwater drainage intensity (comparing the intensively drained metropolitan area with urban areas of the hinterland, which had open drains and some localized stormwater drainage). 2. Communities separated into three groups: eastern hinterland, western hinterland and a metropolitan group. Separation of eastern and western hinterland groups, and of eastern and western sites within the metropolitan group were best explained by patterns of electrical conductivity, basalt geology and annual rainfall. Separation of metropolitan and hinterland groups, and patterns within the hinterland groups were best explained by nutrient gradients (phosphorus, ammonia and total nitrogen). 3. Nutrient concentrations were not only apparently influenced by urban density but also by effluents from small sewage treatment plants and agricultural activities at a few sites. 4. Species richness did not vary consistently between the metropolitan and hinterland groups but within the western hinterland, sites with low nutrient concentrations tended to be more species‐rich than mildly enriched sites. 5. Composition of both diatom and macroinvertebrate communities (assessed in a concurrent study) were sensitive indicators of urban‐derived impacts. However, diatoms were better indicators of nutrient enrichment, while macroinvertebrates were better integrative indicators of catchment disturbance.