The Chowilla floodplain is located 250 kilometres north-east of Adelaide in the Riverland region of South Australia, approximately 40 kilometres north-east of Renmark. It straddles the South Australian and New South Wales borders covering a total area of 17,700 hectares. Chowilla is one of six sites in the Murray-Darling Basin identified as being an Icon Site due to its ecological and cultural heritage significance; and it is also part of the Riverland Ramsar Wetland (recognised as a Wetland of International Importance under the Ramsar Convention). The floodplain contains a complex system of creeks, wetlands and floodplain habitats including the largest remaining area of River red gum woodland in the lower River Murray. It also supports a significant population of Murray Cod and a diverse range of terrestrial and aquatic biota.
Under the National Parks and Wildlife Act 1972, the SA portion of the Chowilla floodplain (which covers about 12,500ha) is gazetted as a Game Reserve. The Chowilla Reserve Management Plan guides land management activities over the area, which is overseen and implemented by the Department of Environment and Heritage (DEH).
The NSW portion of the Chowilla floodplain, known as Kulkurna (which covers about 5200ha) is owned by the NSW Government and is managed by the Department of Natural Resources.
Robertson Chowilla Pty Ltd has operated Chowilla Station as a wool-growing operation since 1865. They are leaseholders of 12,062ha of the Chowilla floodplain in SA. An agreement was struck between DEH and Robertson Chowilla Pty Ltd to exclude grazing from the majority of the Chowilla floodplain (83%) effective as of September 2005.
The Chowilla anabranch, like most of the lower River Murray floodplain is under significant threat. Of all the floodplain Icon Sites, Chowilla is the one system that is most affected by river regulation. As it is located in a semi-arid zone, the water required to maintain the habitat diversity and the unique character of the Chowilla floodplain is almost entirely derived from rainfall occurring well outside the region. The accumulation of salt in the soil profile and lack of flooding is causing severe stress and death of River red gum and Blackbox communities over the majority of the floodplain. Only one third of River red gum trees on Chowilla are currently classified as healthy and it is predicted that many of these will also experience a decline in health in the next 10 years without significant intervention.
To combat the threats to Chowilla, an Integrated Natural Resource Management Project has been established and is being coordinated by the South Australian Murray-Darling Basin Natural Resources Management Board (SA MDB NRM Board). As part of the project, short-term actions have been undertaken including weir pool raising and pumping water into temporary creeks and wetlands. Due to the low likelihood of significant flow being returned to the river and the urgency of the environmental problems, engineering solutions such as construction of major flow management infrastructure have been proposed.
Icon Site Objectives
By mid-2002, it was clear that the health of the River Murray system was in serious decline and that this was threatening the industries, communities and ecosystems that depend on it for their survival. To address this decline, the Murray-Darling Basin Ministerial Council (MDBMC) through the Living Murray Initiative established the First Step decision. This landmark decision aims to achieve specific environmental outcomes and objectives for six Icon Sites across the Basin, one of these assets being the Chowilla floodplain (including the Lindsay-Wallpolla system).
As part of The Living Murray Initiative First Step decision, three broad ecological objectives were identified for the Chowilla Floodplain Icon Site:
To maintain high biodiversity values of the Chowilla floodplain:
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High value wetlands maintained
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Current area of River red gum maintained
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At least 20% of the original area of Black box vegetation maintained
The objectives are clearly focused on maintaining the existing tree vegetation communities, but do not reflect the broader ecological values of the Chowilla floodplain. In support of The Living Murray objectives more specific ecological targets based on values and condition have been developed for the Chowilla floodplain. These include:
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Maintain or improve tree health within 70% of the Red Gum woodland area.
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Maintain or improve tree health within 45% of the Black Box woodland area.
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Provide conditions suitable for regeneration and seedling survival of all vegetation targets.
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Maintain successful recruitment of small and large bodied native fish
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Provide conditions conducive for successful breeding of colonial waterbirds in a minimum of 3 temporary wetland sites at a frequency of not less than 1 in 3 years
These objectives underpin the Integrated Natural Resources Management Project and reflect the intention to maintain and improve existing habitats.
MDBC (2006). The Chowilla Floodplain (including Lindsay-Wallpolla) Icon Site Environmental Management Plan. Murray-Darling Basin Commission (9.1Mb)