A year in the Gwydir catchment: 2024–25

Supporting native fish communities and wetlands, and connectivity were the focus of environmental flows in 2024–25.

Key outcomes

In 2024–25, moderate to wet conditions were experienced throughout the catchment. Water for the environment was delivered to support water-dependent plant and animal communities across the catchment. Environmental water managers worked with partner agencies and stakeholders to deliver water for the environment, which:

• provided an early season stimulus flow for river productivity downstream of the Copeton Dam into the Gwydir River, Carole Creek and Mehi River
• supported river connectivity through the Gwydir River system into the Barwon River via the Mehi River and Carole/Gil Gil creeks system
• inundated the central Gingham Watercourse, creating vital habitat and feeding grounds for waterbirds
• contributed to the resilience of wetlands and the watercourse habitats of the Mallowa Creek
• provided flows into the lower Gwydir Wetlands which supported some vegetation communities in completing their lifecycles.

Catchment conditions

During 2024–25, the Gwydir catchment experienced moderate to wet weather conditions. Combined with favourable environmental water accounts, this resulted in positive water availability.

The carryover of held water from the previous water year enabled good availability of planned environmental water and general security entitlements.

Partnering with Aboriginal peoples

Water for Country represents the planning and delivery of environmental water by the Department of Climate Change, Energy, the Environment and Water in collaboration with Aboriginal people across New South Wales. Where possible, this work continues to evolve, supporting ecological outcomes while also protecting and revitalising cultural places, values and interests.

In the 2024–25 water year, environmental water managers further developed and established relationships with Aboriginal groups and people by:

• supporting 2 Aboriginal members on the Gwydir Environmental Water Advisory Group to engage with the group’s process
• supporting Ozfish work at Whittaker’s Lagoon, which will continue from the 2024–25 water year onward
• the formation of the Bagaaybidi Gali Group, a Gwydir Aboriginal environmental water group, led by the Gwydir Reconnecting Watercourse Country Program. This group is supported by government agencies at the federal and state level. It includes members from Moree, Collarenebri and Mungindi local Aboriginal land councils, Gomeroi Native Title Applicant group, Moree Elder’s group, and youth and health service providers. The Bagaaybidi Gali Group will work and provide advice on issues connected to environmental water.

In 2025, community members and staff participated in a National Indigenous Mapping Workshop as part of the Reconnecting Watercourse Country Program. These activities are building toward a more collaborative, continued relationship.

Watering aims

Under expected dry to moderate weather and water availability, the Gwydir Environmental Water Advisory Group developed its annual environmental water priorities in the Gwydir catchment 2024–25.

Aims for the use of water for the environment were to:

• support waterbirds by providing inundated wetland habitats
• provide opportunities for native fish spawning, movement and recruitment
• support native wetland and riparian vegetation
• support connectivity throughout the valley and opportunistically support Barwon River connection via the Mehi River and/or Carole/Gil Gil creeks.

Other aims were to:

• protect refuge pools during low and cease-to-flow conditions
• keep water available for contingencies, such as supporting the recovery of wetland vegetation after wildfire
• maximise carryover for use in future dry times.

Water delivery

This table and chart provide a summary of 52,779 megalitres of water for the environment delivered in the Gwydir catchment during the 2024–25 water year.

Figures were accurate at the date of publishing but may be adjusted. Watering event numbers in the table and bar chart relate to location numbers marked on the map.

_{Notes: CEW = Commonwealth licensed environmental water; EWA = environmental water allowance accrued under the Water Sharing Plan; NSW = NSW licensed environmental water.}

Outcomes

In 2024–25, environmental water managers worked with stakeholders and the community to deliver flows to support a series of flow outcomes.

The first of the managed deliveries began in August 2024 as an early season stimulus flow in the Gwydir River. This was followed by a minimum flow target at Gravesend and ‘pothole filling’ or smoothing extractive water releases from Copeton Dam. The environmental releases following the stimulus flow were brief due to natural flows at Gravesend and minimal need for pothole filling. These events used 8,717 megalitres of managed environmental water. These flows:

• supported native fish communities, including Carole Creek and Mehi River
• boosted in-system productivity
• provided opportunities for native fish movement and spawning.

A combination of natural flows, planned, and held environmental water was delivered to Gingham Watercourse. Combined with rainfall and river flows in late March to early April 2025, target waterholes and wetlands were filled by season end. This provided refuge for water-dependent species through winter and is expected to persist through to spring 2025. In total 11,124 megalitres of managed environmental water was delivered to Gingham Watercourse, including the licensed environmental volume in the supplementary event in March–April.

To support wetland vegetation and other water-dependent environmental needs in the Lower Gwydir, 9,823 megalitres of NSW and Commonwealth managed environmental water was delivered from December 2024 to March 2025.

Held environmental water delivery of 15,765 megalitres into Mallowa Creek, its watercourse and wetlands provided ongoing support in restoring water-dependent communities over the summer.

Environmental water managers participated in supplementary events throughout the year, delivering water to the Barwon River via Carole/Gil Gil creeks and the Mehi River. This increased the duration of connectivity between the catchments.

Watering events for the water year were communicated to the Gwydir Environmental Water Advisory Group and local landholders via the bimonthly State of the Gwydir Watercourses Report.

Case study: adaptive management and constraints

Environmental water managers use adaptive management strategies to deliver water for the environment. This involves careful consideration of factors such as:

• pre-existing conditions
• ecological needs
• land uses across the floodplain.

Water availability, climatic conditions, scientific research, desired ecological outcomes, and stakeholder perspectives help guide decision-making and optimise environmental benefits.

Since the commissioning of Copeton Dam in 1976, river regulation and subsequent water extraction has significantly reduced the volume of water reaching the Gwydir Wetlands. Grazing enterprises in and around the wetlands, which were sustained by inflows before river regulation, have increasingly transitioned to dryland cropping. Areas that once supported wetlands and grazing, now form part of the highly productive broadacre cropping landscape of the Moree plains.

Our Water for the Environment program aims to support and mitigate the ecological impacts of river regulation and water extraction. Today, the wetlands of the Gwydir floodplain are estimated to be 10% of their original size. What remains of the Lower Gwydir Wetlands, also known as the Big Leather Wetlands, is now surrounded by intensive cropping.

In 2024–25, environmental water managers targeted the Lower Gwydir–Big Leather Wetlands for watering to support the completion of wetland vegetation life cycles and provide critical habitat for waterbirds. To achieve this, managers carefully balanced environmental objectives with active farming operations. For example, flow rates to the Lower Gwydir that are typically set at 250 megalitres/day were reduced to 100 megalitres/day to minimise inundation of downstream crops.

Coupled with planned environmental water, which was at times higher than the target, inundation was minimised for crops around and downstream of the main remnant wetland areas. However, not all the target wetland areas were inundated and vegetation outcomes were suboptimal on the outer edges of inundation.

To reduce these suboptimal outcomes, we are progressing the Reconnecting Watercourse Country program - a Northern Basin Toolkit project. Outcomes for this program are expected to enable farming and water for the environment to coexist with improved confidence, with fewer unfavourable environmental impacts.