Annual environmental water priorities in the Gwydir catchment 2023–24

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

NSW environmental water management teams work with local community 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.

The catchment

The Gwydir catchment covers 25,596 square kilometres. The eastern upland creeks mainly flow into the Gwydir River upstream of Copeton Dam. Downstream, on the western floodplain, the Gwydir River splits into its main distributaries – the Mehi River (south), Carole Creek (north), Lower Gwydir and Gingham Channels (west/central). The Big Leather (Lower Gwydir) watercourse supports the state’s largest stand of marsh club rush. The Gingham Watercourse contains important colonial waterbird breeding habitats. The Gwydir wetlands are home to 4 wetland parcels listed under the Gwydir Ramsar landholder agreement.

The Gwydir catchment supports important Aboriginal cultural values for the Gomeroi/Kamilaroi people.

Water for rivers and wetlands

The Gwydir catchment experienced increasing wet conditions from 2021 to 2023. Major flooding occurred across the Gwydir River floodplain during March and April 2023.

Throughout the 2022–23 water year, water managers used water for the environment to support significant colonial waterbird breeding events in the Gwydir Wetlands after large-scale natural flooding. Other planned watering priorities in the system were achieved through natural and flooding flows.

Water in environmental accounts are currently full. In planning for 2023–24, water managers have applied:

• a set of principles and triggers to guide the watering of key water-dependent assets
• an adaptive approach to support fish and downstream ecological connectivity.

Measures are in place to provide water for any unforeseen water demands, such as for wetland fires and waterbird nesting.

With healthy account balances as of 1 July 2023, the Department of Climate Change, Energy, the Environment and Water (the department) can set aside water for use in future years to support the longer-term resilience of the catchment through drier times.

Aboriginal water management priorities

Water for Country is environmental water use planned by the department and Aboriginal people to achieve shared benefits for the environment and cultural places, values and/ or interests.

We are establishing the Gwydir First Nations Environmental Water Group to provide a platform for Aboriginal people to have a voice and participate in environmental water management, programs and decision-making processes. We are working with members of the Gwydir Environmental Water Advisory Group (EWAG) to ensure Aboriginal people are part of the planning process to ensure decisions made uphold the responsibilities of Aboriginal people as custodians of Country and water. 

Weather and water forecast

As at early June the El Niño–Southern Oscillation (ENSO¹) outlook remains at El Niño alert. This means that while the El Niño–Southern Oscillation is currently neutral, there is a 50% chance that an El Niño may develop later in 2023. This is about twice the normal likelihood. El Niño typically brings hot, dry conditions to Australia, often leading to drought and bushfires.

Long-range forecasts show there's an increased chance of below average rainfall for most of Australia during autumn 2023. El Niño alert is not a guarantee that El Niño will occur but is an indication that some of the typical indicators of El Nino are currently occurring. All climate models surveyed by the Bureau suggest that El Niño thresholds are likely to be approached or exceeded during the southern hemisphere winter.

Water managers have prepared watering plans that consider a range of weather and water availability scenarios. This is known as resource availability scenario planning. Moderate to wet conditions are forecast for the Gwydir catchment in 2023–24.

_{1. ENSO: The interaction between the sea surface and atmosphere over the Pacific Ocean which results in dryer (El Nino) or wetter (La Nina) conditions.}

Key planned actions for 2023–24

Waterbirds

Heavy catchment rainfall, resulting in large river flows and floodplain flooding, may trigger colonial waterbird breeding events in the wetland systems. In response, water managers may provide 15–25 gigalitres (GL) of held water for the environment to support these events.

Native fish

Water managers may use up to 25 GL to support native fish communities this season. In the absence of large natural flows, a release downstream of Copeton Dam will be made to stimulate early season river productivity with supporting environmental flows later in the season.

Vegetation

Water managers may use up to 20 GL across the catchment. Rainfall may trigger delivery of held environmental water into the Mehi River, Carole Creek and/or the Gwydir wetlands system. Water managers may also provide flows into the Mallowa Creek this season to continue ecological improvements and as part of their seasonal planning for this watercourse.

Connectivity

Water managers may provide water for the environment into the Carole Creek, Mehi and Gwydir rivers this season for connectivity support to native fish communities during possible extended dry periods. In addition to inter-catchment connectivity, water managers may consider addressing connection to the Barwon Barwaan River if warranted during the year.

Map of proposed annual priority targets in the water resource plan area 2023–24