Annual environmental water priorities in the Lachlan catchment

Flow management in the Lachlan catchment will boost productivity and build system-scale resilience, where water is available. If conditions evolve into extreme dry, the focus will shift to providing drought refuges and avoiding irretrievable loss of species and habitat.

Priorities for 2019–20

Conditions are likely to be warmer and drier than average in the Lachlan catchment in the coming year.

Water managers plan to boost productivity and build system-scale resilience, where water is available. If dry conditions continue into extreme dry, the focus will shift to providing drought refuges and avoiding irretrievable loss of species and habitat.

In the Lachlan catchment, availability of planned water for the environment is substantially dependent on inflow conditions, while availability of licenced or held water for the environment from carryover is expected to be relatively high compared with other catchments. However, without further rain and inflows in autumn and winter, the Lachlan catchment will shift towards drought management (Extreme Events Policy) with the potential for restricted access to carryover water.  

Water for the environment flows are planned to the Lower Lachlan system to maintain connectivity and protect core vegetation communities. Other flows include deliveries to Merrowie and Merrimajeel creeks to support floodplain, creek and wetland vegetation, aquatic food web and refuge foraging habitat for waterbirds.

The management of water for the environment provides flexibility to respond to natural events that may occur during the year.

Further details on watering priorities for 2019–20 can be found in the Annual Environmental Watering Priorities 2019–20 (PDF 2.8MB).

Highlights from 2018–19

During 2018-19, managed watering events allowed native fish to move and breed along the length of the Lachlan River and its anabranches.

When flows arrived at the Great Cumbung Swamp, they supported partial inundation of the critical reed beds habitat, open water bodies and fringing wetland vegetation. Waterbirds also benefited from this and other refuge, and foraging habitat from Booligal to the Cumbung.

Water manager Joanne Lenehan said water for the environment was delivered to Lake Brewster to support aquatic plant establishment and recovery in the constructed outflow wetlands.

‘The Water Quality Allowance (WQA) was used for the first time to flush blue green algal blooms and prevent blooms re-forming in the lower Lachlan by breaking up stratification and maintaining acceptable levels of dissolved oxygen’, said Ms Lenehan.