Annual environmental water priorities in the Macquarie catchment 2024–25

Water that is allocated and managed specifically to improve the health of rivers, wetlands and floodplains is known as water for the environment.

Our environmental water management teams work with environmental water advisory groups including landholders, Aboriginal stakeholders, partner agencies and other interested community members to develop detailed annual plans for the use of water for the environment in each catchment, including how its use is prioritised.

Water for rivers and wetlands

Projected water for the environment account balances at 1 July 2024 will depend on:

• rainfall in autumn and winter 2024
• possible triggering of the Macquarie Translucent Environmental Water Allowance
• planned maintenance of the Burrendong Dam penstock, which will constrain releases in June, July and August 2024.

It is estimated that available water for the environment at 1 July 2024 will be:

• 270–300 gigalitres (GL) of general security carryover in the regulated Wambuul – Macquarie River, in addition to 9.7 GL of supplementary and 5.8 GL of unregulated water held between NSW and the Commonwealth Environmental Water Holders.
• 18–20 GL of the Cudgegong Environmental Water Allowance carryover in the regulated Cudgegong River, in addition to any general security allocations.

The Macquarie–Cudgegong Environmental Water Advisory Group endorsed rolling and annual objectives for 2024–25. These include using environmental water to support:

• native fish, wetland vegetation, waterbirds and connectivity in the Wambuul – Macquarie River and Macquarie Marshes
• native fish and river processes, including flow variability, in the Cudgegong regulated reach.

Water managers plan to hold a portion of water aside as carryover in general security accounts to support rivers and wetlands over the next 2 to 3 years for future use.

Partnering with Aboriginal peoples

Water for Country is environmental water use planned by the Department of Climate Change, Energy, the Environment and Water (the department) and Aboriginal people to achieve shared benefits for the environment and cultural places, values and/or interests.

The Wiradjuri Wongaibon people of the Trangie area have a representative on the Macquarie–Cudgegong Environmental Water Advisory Group.

In 2024–25, we hope to continue to improve systems and representation to better include the voice of the Wiradjuri and Wayilwaan nations in environmental water planning. This includes to:

• continue to build local relationships with Aboriginal people
• support Aboriginal representatives to include their priorities in environmental water advisory group discussions
• partner with Aboriginal people to examine watering viability for selected assets, including areas near Trangie and Warren
• work with organisations across the catchment to inform the 2024 review and update of the Macquarie and Castlereagh Long-Term Water Plan.

Weather and water forecast

As of June 2024, the El Niño–Southern Oscillation outlook is neutral. That is, neither La Niña nor El Niño conditions are favoured as oceanic and atmospheric indicators have returned to neutral levels. International climate models suggest neutral El Niño–Southern Oscillation conditions will persist through the southern winter, but there are some signs that La Niña conditions could form later in the 2024–25 water year.

Water managers have prepared watering plans that consider a range of weather and water availability scenarios. This is known as resource availability scenario planning.

Resource availability scenario

This table provides details about how we plan for different resource availability scenarios. Wet trending towards moderate conditions are forecast for the Macquarie catchment in 2024–25, which means water availability planning will follow the ‘moderate’ and ‘wet’ scenarios.

Key planned actions

Native fish

Water for the environment will aim to support native fish populations in the mid-Wambuul – Macquarie River and regulated Cudgegong River.

The fish species supported will depend upon weather conditions. If river flows can be kept relatively stable, water managers will target species, such as Murray cod and eel-tailed catfish, which benefit from steady flows for breeding. Water managers will consider actions for flow specialists, including golden perch if larger, more variable flows occur.

Waterbirds

Proposed watering actions will benefit waterbirds by providing foraging habitat and general waterfowl breeding opportunities in inundated wetland areas and stream channels.

Flows targeting the maintenance of wetland vegetation in the Macquarie Marshes will support nesting habitat for large-scale aggregations of waterbirds. This will ensure the wetland will be ‘event ready’ should weather systems generate a suitable major flow event.

Vegetation

Actions will depend upon flow conditions and rainfall. At a minimum, it is expected that environmental water managers will deliver a flow pulse in spring 2024 to:

• the semi-permanent wetland of the Macquarie Marshes, an area of approximately 20,000 hectares, to support core wetland vegetation to grow, flower and set seed
• support riparian vegetation along the mid- and lower-Wambuul – Macquarie River and the regulated Cudgegong River
• help recharge shallow groundwater systems and support dependent vegetation.

Connectivity

Connectivity of the Macquarie catchment to the Barwon River has been consistent through 2021, 2022 and 2023. With a drying Macquarie Marshes, it is expected spring flows in 2024 may provide a limited-duration ecologically valuable flow connection along the lower Wambuul – Macquarie River to the Barwon River. Depending on water levels, this may allow native fish to move between catchments and provide base flows in the unregulated Barwon River to Brewarrina.

Map of proposed annual priority targets in the water resource plan area 2024–25