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Environmental flow setting as a tool for maintaining ecological health in rivers has been a focus of debate for many years. Environmental flow setting often involves the establishment of base flow levels below impoundment structures as well as setting flushing flows in order to control excess periphyton accrual and sedimentation. The role of bedload transport and substrate stability is recognised as an integral part of effectively managing benthic communities, but environmental flow regulations often do not focus on managing sediment processes. Environmental flows which fail to scour periphyton have been attributed to increased biomass accumulation through increasing nutrient supply to periphyton mats. It may therefore be more effective to establish environmental flow models based on incipient motion thresholds. The aim of these models would be to establish target near-bed velocities as opposed to discharges …