Lachlan catchment
Legend
Ramsar site
DIWA site
| Security | Registered entitlements (ML) |
|---|---|
| High | 733 |
| General | 85,249 |
| Total | 85,982 |
Water use planning
Environmental Water Delivery: Lachlan River collates current knowledge of the operational and administrative arrangements for the delivery of environmental water to the Lachlan River. The document provides an overview of the environmental assets and potential environmental water use options. This work has been undertaken to support the efficient and effective use of environmental water and to engage communities on how this may best be achieved. This aims to encourage community discussion and feedback on the use of environmental water, to identify future opportunities and recognise operational risks and constraints. Comments on the document are encouraged and can be provided to: ewater@environment.gov.au
Environmental watering in the catchment in 2011-12
Environmental watering in the catchment in previous years
During 2010-11, the Lachlan catchment experienced its first significant flows in over a decade. Significant rainfall in the catchment caused large volumes of water to flow through to the Great Cumbung Swamp, at the end of the system. A total of 7.4 gigalitres of Commonwealth environmental water was delivered to sites and provided as river flows within the Lachlan catchment during the year.
During spring and summer, Commonwealth environmental water was used to build on natural flows and supported bird breeding events at Merrowie Creek and Merrimajeel Creek in the Booligal wetlands. The event included bird breeding of approximately 64,000 pairs of straw necked ibis and 600 pairs of the nationally listed glossy ibis, as well as royal spoonbills, white ibis and freckled ducks. This was the first significant bird breeding event in the Booligal Wetlands since 2000. Further Commonwealth environmental water was delivered to Merrowie and Merrimajeel Creeks in winter 2011.
For further information about Commonwealth environmental watering in the Lachlan and the outcomes achieved, please refer to the Commonwealth environmental water Outcomes Reports and Annual Reports.
Catchment profile
Where is it?
The Lachlan Valley catchment in central western NSW centres on the Lachlan River. It is bounded to the east by the Great Dividing Range, to the north by the Macquarie, to the south by the Murrumbidgee and the north-west by the Darling catchment. Rising near Gunning in the east, the Lachlan River travels around 1,400 km. The diverse landscape influences the vegetation, which ranges from temperate forests, woodlands and grasslands in the east to semi-arid woodlands, mallee and shrublands in the west.
The catchment area is 86,554km2, or 8.3 per cent of the total MDB area. It is essentially a terminal system with the Lachlan River ending in the extensive wetlands of the Great Cumbung Swamp. The Lachlan River itself is only intermittently connected to the Murrumbidgee River when both rivers are in flood. Tributaries to the Lachlan include Belubula, Boorowa and Crookwell Rivers. The Lachlan catchment is regulated by the two major water storages of Wyangala Dam (capacity 1,220 GL) and Carcoar Dam (capacity around 36 GL), and other regulating weirs such as Booberoi and Lake Brewster.
What makes this place so special?
The Lachlan catchment is an ecologically significant area because it includes:
- wetlands in the lower western region covering 471,011 ha, 95 per cent of which are on the floodplain
- nine areas listed on the Directory of Important Wetlands in Australia (DIWA) with particular value as waterbird and migratory bird habitat
- native fish species including the Australian smelt , freshwater catfish , silver perch , golden perch , big-headed gudgeon and western carp gudgeon
- habitat for threatened species, such as Sloane's froglet, Australian painted snipe, osprey, blue-billed duck and the fishing bat
- areas of river red gum forest and woodland, black box woodland and lignum.
The nine nationally important wetlands in the Lachlan catchment are: Booligal Wetlands, Murrumbidgil Swamp/ Lake Merrimajeel, Cuba Dam, Merrowie Creek (Cuba Dam to Chillichil Swamp), Great Cumbung Swamp, Lachlan Swamp, Lake Brewster, Lower Mirrool Creek Floodplain, and Lake Cowal/Wilbertroy Wetlands. The Booligal Wetlands and the Great Cumbung Swamp are notable sites as both wetlands are well known for providing habitat for both large numbers and species of waterbirds, particularly straw-necked, white and glossy ibis, when the area is flooded. The catchment has been recorded to support 80,000 breeding pairs of ibis. The Great Cumbung Swamp also contains one of the largest stands of river red gums in NSW.
What does the latest science say about the ecological health of the catchment?
The Murray-Darling Basin Commission Sustainable Rivers Audit (SRA) used several criteria to rate the overall health of river ecosystems in the Murray-Darling Basin. The SRA reports the overall health of the Lachlan Valley Catchment as being very poor.
The CSIRO Sustainable Yields report on the Lachlan Valley Catchment indicated that the current level of surface water extraction in the Lachlan River (Lachlan Valley Catchment) is moderately high, with 28 per cent of average available water being diverted for use. Under the best estimate 2030 climate conditions there would be a decrease of 11 per cent in water availability.
Note that the boundaries of this catchment as defined by the Sustainable Rivers Audit and the Sustainable Yields report differ slightly to the boundaries used here.