A year in the Namoi catchment: 2024–25

In 2024–25, rainfall and natural river flows meant only a small volume of environmental water was required to support native fish and maintain river connectivity in the Peel and Lower Namoi rivers.

Key outcomes

From winter through to late December 2024, the Namoi catchment experienced a range of rainfall generated flows, from small freshes to bankfull events.

Dry conditions returned in January and flow in the Lower Namoi decreased. To support native fish during this period, 5,921 megalitres of environmental water was delivered to the Lower Namoi. Rainfall returned during this delivery in early April, and the watering event was stopped. Large-scale flooding of the Lower Namoi River and its floodplain followed.

The Peel River enjoyed similar river flows and beneficial conditions throughout the year. Plans were made for an autumn delivery, but the return of rain meant no water for the environment was used in the Peel River.

In the Lower Namoi River, Commonwealth environmental water was used to maintain connectivity between the Namoi and Barwon rivers during autumn. This provided vital habitat and enabled native fish to move between the 2 river systems.

Catchment conditions

The 2024–25 water year began with a wet winter, and moderate rainfall persisted across the catchment until late summer, when conditions turned dry. This was followed by significant autumn rainfall, causing widespread flooding in the Peel and Lower Namoi catchments. Rainfall continued into winter, providing beneficial natural flows throughout both rivers.

At the beginning of the water year, Chaffey Dam was at 100% of its full supply level, Split Rock Dam was at 96% full supply level, and Keepit Dam was at 40% full supply level. To provide water supply to access licences located in the Lower Namoi for summer irrigation, a bulk water transfer from Split Rock to Keepit Dam occurred between November and February. Autumn rainfall produced inflows to all 3 dams, with final supply levels reaching approximately 80% for Keepit, 78% for Split Rock, and 100% for Chaffey.

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. This work continues to evolve, supporting ecological outcomes while also protecting and revitalising cultural places, values and interests.

Environmental water managers continue to build relationships with Aboriginal people in the catchment. Work with the Dharriwaa Elders Group and Gomeroi representatives through stakeholder advisory groups for environmental water delivery in the Namoi and Peel rivers is ongoing.

Water managers have supported a project led by the Department of Primary Industries and Regional Development – Fisheries, which aims to include cultural knowledge, experience and perspectives in the fish and flows framework to develop flow-related cultural objectives in support of fish conservation.

Watering aims

With full water accounts, environmental water managers identified water-use objectives in the Annual environmental water priorities in the Namoi catchment 2024–25, which were to:

• increase habitat and mobility opportunities for native fish across the Namoi and Peel rivers, and platypus in the Peel River
• provide spawning opportunities for native fish species
• increase connectivity between the Namoi and Barwon rivers
• improve water quality.

The fluctuating conditions over the water year influenced the environmental watering approach. Water managers adapted plans in response to changing catchment conditions and environmental needs. The year was characterised by wet and dry conditions, with the widespread autumn flooding key in recharging the river systems.

Water delivery

This table and chart provide summaries of the 5,921 megalitres of water for the environment delivered in the Namoi catchment during the 2024–25 watering 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.}

Outcomes

In 2024–25, environmental water managers adopted an adaptive approach to support the long-term health of the Namoi and Peel rivers. A key action was the delivery of 5,921 megalitres of Commonwealth environmental water between 22 March and 10 April 2025.

This release was designed to support connectivity in the Lower Namoi and Barwon rivers, and encourage native fish to migrate between the 2 systems. As a result, continuous connectivity was maintained between the Lower Namoi and Barwon rivers for the entire water year. This release supported river productivity and increased food availability to increase the health of other animals such as turtles, platypus, and water rats before cooler winter arrived.

A sequence of bankfull natural flow events occurred downstream of Chaffey Dam. These flows were beneficial to riverbed habitat as they scoured and moved instream sediment and stripped away built-up biofilm from the river’s gravel beds.

Case study: the time value of water

Environmental water managers face the challenge of using water at the optimal time for the greatest environmental benefit. This is especially true in the Namoi catchment, where environmental water holdings are small, at just 32 gigalitres, compared to 334 gigalitres in the regulated Macquarie.

Water for the environment can provide crucial support for rivers, wetlands, waterbirds, and native fish. However, natural flow events can also meet most environmental water demands and reduce the need for direct intervention. This was seen during the large-scale flooding in the Namoi catchment in 2024–25.

Wet years are often followed by dry periods. During these dry times, environmental water is used to prevent irreversible damage and permanent loss of water-dependent plants and animals. For example, water is released to maintain river pools and create refuges for native fish. These fish can then serve as breeding stock and help populations recover once the drought breaks.

In 2024–25, environmental water managers in the Namoi used a small portion of their allocation and carried over the remainder into the next year. This carryover:

• provides the flexibility to plan and release water when it will have the most significant impact
• allows effective use of a limited resource to support the long-term health of the Lower Namoi River.

The Peel River lacks this flexibility to carry over unused water. This presents a number of challenges:

• water managers are unable to plan for the long term
• native fish and other water-dependent species face increased risk during droughts due to limited water being available
• restriction of efforts to maintain the long-term health and resilience of the Peel River ecosystem.