Monitoring the Darling Anabranch, NSW: a pilot study

"2003".

Project Number: Hydrologic & Aquatic Biota Rehabilitation on the Great Darling Anabranch M/BUS/61 HB66A.

MDFRC item.

A number of environmental issues associated with the regulation of flows in the Darling Anabranch have been reported. These include channel siltation, salinization, the increased incidence of blue-green algal blooms, the proliferation of some aquatic plants (e.g. Cumbungi) and fish (e.g. Carp), reductions in the numbers of native fish and yabbies, and the restriction of fish movement. To date, however, environmental monitoring within the Anabranch has been largely ad hoc in nature and lends only cursory support to these reports. This study presents the findings of two surveys of the Anabranch conducted during June and December 2002. Issues identified during the surveys were used to generate a framework for the future monitoring of the system. Because the processes that drive each of the recognised issues operate over different spatial and temporal scales, separate monitoring programs are proposed. The piping of water for domestic and stock use along the Anabranch as proposed by the DAMP (Nias 2002) provides an opportunity to address key environmental issues within the Anabranch by allowing for the removal of in-stream barriers and the re-instatement of a more natural (i.e. variable) water regime. Gauging the impacts of these actions will to a large extent depend on the availability of adequate reference (i.e. current) ecological data. As such data is scarce, it is vital that the suggested monitoring programs be implemented as soon as possible and that ongoing funding be secured. The success of actions aimed at addressing key environmental issues will depend on the level of understanding of the links between aspects of the proposed flow regime and ecosystem responses. It is anticipated that altering the flow regime of the Anabranch will enhance a broad range of environmental values. More precise modelling of ecosystem responses to specific flow regimes and flow volumes will be possible once channel topography has been mapped.