Annual environmental water priorities in the Macquarie-Castlereagh catchment

Water management will focus on continuing the ongoing task of drought recovery by maintaining drought refuges and core aquatic ecosystem values in the mid and lower Macquarie River.

Priorities for 2021–22

In 2021–22, water managers in the Macquarie will continue the ongoing task of drought recovery in the mid and lower Macquarie River.

Some riparian vegetation along the Mid and Lower-Macquarie River will be supported where flows are present that will also recharge groundwater systems to help sustain trees that rely on this water source.

An inundation event in the Macquarie Marshes will be provided from August to November 2021 through tributary flows and managed environmental flows.

An event in October will support fish hatched in 2020 to grow and be recruited into the adult population, while targeting a native fish breeding event for Murray cod, freshwater catfish and other small-bodied native fish. This will conclude in November with a pulse flow, allowing newly hatched fish to spread through the catchment.

In late winter early spring, a pulse is expected to create 6 to 8 weeks of flow connection between the Macquarie and Barwon rivers with the intention to allow young golden perch to travel from the Barwon River to the Macquarie-Castlereagh catchment.

Further details on watering priorities for 2021–22 can be found in the Macquarie–Castlereagh Catchment – Water for the Environment: Annual Priorities 2021–22 (PDF 1.4MB).

Highlights from 2020–21

The water year 2020-21 saw active engagement with the Macquarie-Cudgegong Environmental Water Advisory Group to establish opportunities for environmental outcomes from environmental water. Strong tributary flows until late September supported these opportunities.

Key actions included: 

  • the use of water for the environment in October to stabilise flows in the Mid-Macquarie River around Dubbo to support breeding of native fish species like Murray cod and freshwater catfish
  • a pulse flow to the Macquarie Marshes in November to support native fish dispersal and inundation of the Marshes for wetland plant growth
  • a low flow to the Marshes and Lower Macquarie River throughout summer to maintain core inundation of wetland areas.

For the first time since 2006, the Translucent Environmental Water Allowance settings were altered to seek drought recovery outcomes. This included setting maximum flow rates at Marebone Weir to encourage longer-duration events over shorter, high-flow rate events.

The monitoring of native fish in the Mid-Macquarie River funded by the Commonwealth Environmental Water Office indicated a successful breeding event with young cod, catfish and other fish species. While flows into the Marshes did not produce a large-scale colonial waterbird breeding event, there were positive signs of wetland vegetation recovery from the record drought of 2017 to 2020.