Floodplain wetlands are important components of river systems, supporting primary production, rich biodiversity values, nursery habitats and refuges from conditions in the main river channel. Since European settlement and the onset of river regulation, the flow regimes of the Lachlan River have been substantially changed. Lachlan wetlands have also suffered from habitat degradation, the introduction of exotic species such as carp, increased floodplain barriers and water extraction.
The natural flooding regime for wetlands in the Lachlan region would have been winter/spring inundation once every 2 to 10 years. Since the draining of floodplains and construction of dams, weirs and levees to serve agriculture and rural towns, these wetlands have been increasingly isolated from the river and have had their flooding frequency greatly reduced. Where this has occurred over long periods of time, there is the potential threat to a wetlands ability to naturally recover when re-flooded, due to destruction of soil seedbanks and the decline of long-lived species such as river red gums.
There are major environmental benefits to restoring these floodplain wetlands to a more natural watering regime. Healthy wetlands can provide areas of biodiversity, nursery areas for native fish and crustaceans, nutrient sources for the rivers, and natural flood buffers. Wetlands can also provide extra water storage, tourism and recreational opportunities and, if managed appropriately, may support cropping or grazing when dry. They are also culturally important to local Aboriginal communities.
To best manage environmental flows the catchment needs to be addressed in a holistic manner. Every change that is made to land and water management within the riverine system may have benefits or repercussions further downstream and these impacts need to be considered. The wetlands and associated floodplains, are important components of the river system and it is necessary to address the entire river system when planning and delivering environmental flows.
