Lachlan River

Lachlan River 
Drought Stage

Stage 1 - Normal management

Stage 1 normal operations on 3 September 2020 eased from recovering since 14 August 2020. Previously stage 3 severe water shortage.

Storage Level
  • Wyangala Dam at 70% (852 GL) of active storage compared to 27% (335 GL) on 1 July 2019.
  • Zero for general security in 2019/20 and 2020/21 until 4 September 2020 when 28% general security allocation announced, increased to 38% in November 2020 and progressively to 64% in April 2021.
  • All restrictions on general security carryover lifted on 10 August 2020. Carryover previously restricted to 57% in 2020/21 and half the active amount further restricted in 2020/21.
  • Last general security allocation (prior to September 2020) made in August 2017.
  • Full town and domestic and stock allocations but reduced high security allocations to 87% in 2019/20 and 70% in July 2020. Full high security allocations announced on 10 August 2020.
  • Annual replenishment flows completed in 2019 to provide domestic and stock water.
  • Water Quality Allowance was released in January/February 2019 to reduce issues with blue-green algae outbreaks in the lower Lachlan.
  • Environmental water was delivered to Booligal Swamp in June, Booberoi Creek from June to August and mid Lachlan wetlands from July 2019.
  • Environmental release from Wyangala Dam commenced in September 2019. This provided water into Booberoi Creek, topped up Brewster weir pool and arrived in the Great Cumbung Swamp in mid November 2019.
  • Replenishment flows to lower Lachlan creeks ceased from 8 December 2019 and flows to the Willandra Creek system ceased from December 2019 because of dry conditions.
  • Water Quality Allowance was delivered in the Lower Lachlan during February 2020 to assist with maintaining end of system flows and to improve water quality.
  • Assistance provided to Cowra and Condobolin to access groundwater supplies.
  • Translucent environmental releases made from Lake Brewster between August and September 2020 to conserve volumes in Wyangala Dam. Translucent releases re-commenced from Wyangala Dam in late October.
  • Stock and domestic replenishments commenced in September 2020.
  • Release of up to 5.5 GL of the Water Quality Allowance commenced in late December 2020 and continued until March 2021 to mitigate the risk of low dissolved oxygen levels in the lower Lachlan. Releases were being used to target a flow of around 100 ML/day at Booligal Weir.
  • A further 1 GL of the Allowance was used in January 2021 to offset releases from lake Brewster which had high algal counts and were causing extremely low DO levels at Willandra Weir.
  • Inflows into the Lachlan normally occur in winter/spring. Minimal inflows occurred in 2019–close to the record minimums.
  • Since July 2020 substantial inflows have occurred increasing the capacity of Wyangala Dam from 16% at the start of July 2020 to 70% in April 2021.
  • Ongoing issues with low dissolved oxygen levels in the Lachlan River which can cause fish deaths.
  • Inflows to the Lachlan were well below minimums in December 2020. However, in March 2021 the Lachlan catchment experienced very wet conditions and good inflows to Wyangala Dam.
  • Domestic and stock, towns and high security licences will be allocated 100% of entitlement.