A year in the Barwon-Darling catchment: 2023–24

Connectivity and native fish outcomes were the focus for environmental water managers in the Barwon–Darling catchment in 2023–24.

Key outcomes

Under moderate conditions, environmental water managers worked with the Commonwealth Environmental Water Holder to protect licenced water for the environment throughout late 2023 and early- to mid-2024. Licensed water for the environment protected natural inflows from the tributaries and local runoff, primarily in small fresh events and the lead and tail of a large fresh event.

Outcomes included:

• favourable conditions for native fish recruitment during summer
• connectivity with Menindee Lakes and the Lower Baaka – Darling with approximately 630 gigalitres of flow passing Wilcannia
• periodic inundation of riparian zones from small and large fresh events
• flows and inundation of priority instream Aboriginal sites.

Catchment conditions

During the first half of the 2023–24 water year over winter and spring, the Barwon–Darling catchment and its tributaries experienced below average rainfall. Conditions were relatively warm and dry and there were relatively few small flows.

This changed in December 2023, with rainfall at or above average for the remainder of the water year. This created a series of flow events over the summer of 2023–24 and autumn 2024, with significant contributions from the regulated eastern and unregulated western tributaries.

Partnering with Aboriginal peoples

Water for Country is environmental water use planned by the Department of Climate Change, Energy, the Environment and Water and Aboriginal people to achieve shared benefits for the environment and cultural places, values and/or interests. In the 2023–24 water year in the Barwon–Darling catchment, environmental water managers:

• continued work supporting Aboriginal peoples between Bourke and Mungindi to identify priority sites for environmental watering
• supported nation-led planning for the Toorale Cultural Watering Plan
• started to build relationships with Barkindji through the Toorale Joint Management Committee and meeting with Barkindji Prescribed Body Corporate. 

Watering aims

The Annual environmental water priorities in the Barwon-Darling Barwaan-Culliwatta-Baaka rivers 2023–24 were developed in response to moderate weather and water availability.

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

• increase connection between the Barwon–Darling River to Menindee Lakes
• support flow events that help recruit native fish into the local population
• support identified Aboriginal peoples’ priorities where possible.

With moderate conditions, environmental water managers used an adaptive approach to protect small freshes and the lead and tail of large fresh events to contribute to connectivity, maintain river functioning and improve ecological health and resilience.

Water delivery

This table and chart provide a summary of 64,436 megalitres of water for the environment protected in the Barwon–Darling catchment during the 2023–24 watering year.

This saw the addition of held environmental water from the Macquarie, Namoi, Gwydir and Border river systems protected under active management when it reached the Barwon–Darling. Of this held environmental water, 44,971 megalitres entered Lake Wetherall.

Figures are accurate at the date of publishing but may be adjusted. The watering event number in the table and chart relate to the location number marked on the map.

Notes: CEW = Commonwealth licensed environmental water.

Outcomes

In 2023–24, environmental water managers worked with stakeholders and the community to protect water for the environment. Supporting assets across the catchment such as native fish, riparian and wetland vegetation, and system connectivity.

Under active management rules, NSW and Commonwealth unregulated environmental water licenses were used to protect water for the environment to support connectivity along the Barwon–Darling River. Unregulated licenses were used during summer and autumn as natural events entered the system. Water was primarily protected in the reach upstream of Collarenebri and between Bourke and Louth. Active management protected flows beyond the river reach to Menindee Lakes.

Case study: regulated tributaries boost connection

Through spring and early summer, in addition to environmental water from Barwon–Darling licences, the Barwon–Darling received 31,476 megalitres of held environmental water from the regulated tributaries. These tributary flows were protected under active management along the length of the unregulated Barwon–Darling system just upstream of Menindee Lakes.

The Macquarie catchment provided the largest contribution of over 13,300 megalitres during a continuous period of 111 days. This was followed by some smaller contributions.

The Namoi and Gwydir catchments contributed over 8000 megalitres each. The Gwydir flows connected via the Carole-Gil Gil system and the Mehi River. Smaller flows were also received from the Border Rivers system.

These flows contributed greatly to base flows and small fresh events at critical times for native fish spawning and recruitment in the Barwon–Darling and downstream in Menindee Lakes.