Active management of environmental water in the Murray–Darling Basin

Abstract Water resource development in the Murray–Darling Basin, focussed on regulating the naturally highly variable stream flows to provide security of supply and support the extraction of large volumes of water for a range of consumptive uses, dominated much of the 20th century. These developments changed the natural flow regimes and resulted in negative environmental impacts. As these issues began to emerge, Commonwealth and state governments responded with decades of water reform focussed on addressing the impacts of flow regulation and water diversion on river and floodplain ecosystems. The first formal allocation of water for the environment was made in 1967, and since then, environmental water provisions have been implemented in many forms and localities across the Basin. Mechanisms for providing water for the environment include both ‘passive’ and ‘active’ approaches. Passive approaches include rules to protect a flow window or restrict consumptive use, whilst active approaches include the management of the volume, timing, and location of environmental water in real time, in response to the prevailing river flows and climatic conditions. The amount of environmental water that is available for active management in the Murray–Darling Basin has grown significantly over the past decade as a result of the purchase of water entitlements and from water savings generated by modernising irrigation infrastructure. This chapter covers the experience of environmental water holders in actively managing water for the environment in the Murray–Darling Basin. Adaptive management (including the need for effective relationships between managers and scientists), building legitimacy with local communities, and integrating environmental water into broader land and water management are all highlighted as key components to successful environmental water management.