Introduction << BACK TO CONTENTS How does water for the environment work? Water for the environment is released into rivers to mimic some of the flows that would have occurred naturally before the construction of dams, weirs and channels. This is vital to maintain the physical, chemical and biological health of rivers. Environmental water managers generally prioritise returning some of the small and medium sized river flows that are essential in the life cycles of native plants and animals. These flows can move sediment and nutrients through river systems, connect habitats and improve water quality. The timing, duration and volume of water for the environment is designed to support the plants and animals that rely on it. For example, fish such as Australian grayling rely on an increased river flow in autumn as it signals them to migrate downstream for spawning — when fish release eggs. Many wetlands are now either disconnected from the rivers that used to naturally fill them or are permanently connected to rivers or channels. This means that some wetlands do not get enough water, and others get too much. In wetlands, environmental water managers aim to mimic the natural wetland wetting and drying cycles on which many plants and animals depend for their diversity and long-term resilience. For example, where wetlands and floodplains have been cut off from natural river flows, water for the environment can be used to reconnect these areas, sometimes via irrigation infrastructure (such as pumps, channels and regulators). Before and after the development of dams, weirs and channels Rivers and wetlands provide water and land that is important to farms, towns, and industry. As a result, many of Victoria’s rivers and wetlands have been highly modified. For example, instead of water flowing across the landscape naturally, water is captured in storages by dams and weirs, diverted via pipelines, levees and constructed channels and used for towns, cities, industry and farming. Some of our rivers give up more than a third, and sometimes half, of their water for farms, homes, and businesses. Instead of flowing naturally, with high flows in winter and low flows in the hotter summer months, many rivers now run higher when water needs to be delivered for farming and urban use. These changes have affected water quality and interrupted many of the natural river and wetland processes native plants and animals need to survive, feed and breed. 5 | Victorian Environmental Water Holder
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