The extended period of low flow in the River Murray, coupled with low rainfall, has led to significant stress and in many cases the death of significant vegetation on the Chowilla floodplain. The majority of stressed River red gum communities are associated with temporary wetlands and creeks. Many of these areas have not experienced watering since 1996.
In 2004, a watering trial undertaken on Monoman Island demonstrated that stressed trees respond rapidly to an increase in available fresh water. Based on the success of this trial, a program of watering projects has been undertaken. A total of 24 sites have been watered on the Chowilla floodplain between 2004 and 2008.
Weir pool manipulation is a management option that provides the opportunity to artificially enhance river levels by raising weir levels to create ponding or flow retention. Alternatively, weir pool manipulation can be used to lower weir levels to reinstate a natural drying phase to wetlands/creeks that have been artificially inundated for long periods of time as a result of flow regulation. Manipulating locks and weirs also provides the opportunity to regulate floods by altering the extent of inundation and/or duration of these events, within a limited flow range.
Under entitlement conditions, locks 5 and 6 influence the Chowilla floodplain. Manipulation of these structures in isolation provides relatively limited opportunity. However, manipulation in conjunction with other management actions can provide significant ecological benefits.
Short-term solutions such as weir pool manipulation and pumping onto wetland sites continues to be effective at the local scale (less than 5% of the Chowilla floodplain has been watered in this way to date), but is only considered as supporting the longer-term Chowilla Creek environmental regulator solution. Approximately $2m has been invested in floodplain watering on Chowilla over the last 3 years resulting in significant ecological benefit, but it is not considered a viable approach for broader floodplain management.
Schultz, M. and Lenon, E (2008). Ecological Responses to the 2008 Chowilla Environmental Watering Program. Report prepared for the SA MDB NRM Board.
Brett Lane and Associates (2004) Survey of River Red Gum and Black Box Health along the River Murray in New South Wales, Victoria and South Australia. Report prepared for the MDBC (736kb)
Treilibs, C. (2007) Distribution of the Bush Stone Curlew Burhinus grallarius in relation to environmental watering on the Chowilla floodplain. Report for the DEH (1.8Mb)
Gehrig, S. (2005) Watering of River Red Gums (Eucalyptus camaldulensis) on Chowilla floodplain. Report for DWLBC (1.1Mb)
Aldridge, K. Deegan, B. Nicol, J. Burch, M. and Brookes, J. (2006) Ecological response to watering trials on Chowilla Floodplain, 2005-2006. Report for DWLBC (7.4Mb)
Overton, I.C. and Jolly, I.D. (2003). Investigation of Floodplain and Groundwater Interactions at Chowilla. CSIRO and DWLBC (17.4Mb)