The unregulated rivers of the Northern Murray-Darling Basin
The Northern Murray-Darling Basin includes the Northern Intersecting Streams - Condamine-Balonne (Narran Lakes), Warrego (Toorale) and Moonie; and the Barwon-Darling River. These rivers support many unique plants and animals as well as domestic and agricultural water use, cultural values and practices of local Aboriginal Traditional Owners, and tourism and recreation.
The frequency and volume of water available to sustain the rivers, floodplains, lakes and wetlands of the Northern Basin have been affected by the diversion of water to support domestic water use and agriculture. This affects habitat, key breeding sites and drought refuges, threatening the survival of the many native animals, plants, birds and fish unique to the region.
The region has a number of sites that are important for their environmental values.
- The Lower Balonne River floodplain covers two million hectares in Queensland and New South Wales and supports the largest number of wetlands of any catchment in the Basin.
- Narran Lakes is an internationally significant Ramsar site for waterbirds, recording some of the largest and most diverse waterbird breeding events, and the highest densities and greatest abundances of waterbirds in Australia.
- The Warrego catchment along with the Condamine-Balonne supports the largest area of wetlands of any catchment in the Murray-Darling Basin. The Warrego, Moonie and Condamine-Balonne catchments are also increasingly recognised as important for golden perch, with fish spawned in these catchments dispersing to sites across the Northern Murray-Darling Basin and possibly even into the Southern Murray-Darling Basin.
- The nationally significant Warrego River Waterholes near Charleville are an important breeding area for native fish including Murray cod and silver perch. The Yantabulla Swamp is a mosaic of channels, floodways and wetlands within the Cuttaburra Creek system, that supports large numbers and a high diversity of waterbirds and when flooding provides breeding sites for ducks and colonial waterbirds.
- The Warrego Western Floodplain (Toorale) supports diverse floodplain and wetland vegetation communities and provides habitat for numerous waterbird species listed as threatened under Australian and state government legislation or in migratory bird treaties.
- The Moonie River has relatively long and deep waterholes that are critical for sustaining healthy native fish populations in (the often) long periods between flows in this system.
Map of the Northern Intersecting Streams showing Narran Lakes, Cuttaburra systems and Toorale (CSIRO 2007)
- The Barwon-Darling River covers a vast scale connecting the lower floodplain rivers, lakes and wetlands in the Northern Basin from Mungindi to Menindee, providing a critical dry period refuge and movement corridor for fish and waterbirds. The river connects the Northern to the Southern Murray-Darling Basin.
- The Talyawalka Anabranch-Teryaweynya Creek supports many thousands of waterbirds when inundated and is known for its coolibah and blackbox vegetation.
Map of the Barwon-Darling catchment showing Toorale at the junction of the Warrego and Darling rivers (CSIRO 2007)
Delivery of environmental water to date (as of September 2022)
Commonwealth water for the environment (unregulated entitlements) has been provided in the Barwon-Darling, Condamine-Balonne, Moonie and Warrego systems since 2010–11. This water helps protect a portion of the flow to help maintain natural river flows, provide drought refuge and habitat, support native fish populations and vegetation, and to build ecosystem resilience.
Like much of the northern Basin, the Intersecting Streams and Barwon-Darling system experienced very hot and dry conditions between 2017–18 and 2019–20. This resulted in long periods of low or no flows, which reduced the extent and quality of refuges and likely impacted on the condition of aquatic communities throughout these rivers.
Widespread rainfall in late summer and autumn 2020 provided much needed water to most tributaries of the Barwon-Darling, and into the Barwon River itself. These flows triggered unregulated entitlements of Commonwealth water for the environment in the Barwon-Darling and Intersecting Streams, helping to support natural flows, the replenishment of waterholes and reconnection to the Barwon River. Additional water was also secured in the Lower Balonne system under a pilot project to support the Narran Lakes.
Generally drier conditions returned for the first part of 2020–21 across parts of the northern Basin. Commonwealth water for the environment was delivered to the Barwon-Darling from the Gwydir and Border Rivers to support native fish as part of the ‘Northern Waterhole Top-up’ flow. Conditions improved again in autumn 2021, with rainfall again triggering Commonwealth unregulated entitlements in the Warrego, Moonie, Condamine-Balonne and Barwon-Darling systems, helping to protect a portion of the natural river flows, increasing connectivity and supporting native fish.
Due to ongoing rainfall, good flows continued in the northern unregulated rivers during the 2021-22 water year. These flows helped the system recover after the long dry and helped native fish to move as far downstream as Menindee Lakes and beyond. Around 44 gigalitres of Commonwealth water for the environment was protected in the Barwon-Darling early in the 21-22 water year, with rainfall-fed flows doing the job for the remainder of 21-22. Along with recovery and fish movement, flows in the Lower Balonne during 21-22 also helped support waterbirds breeding at the internationally significant Narran Lakes (Dharriwaa) for the first time since 2012. Almost 317 GL of Commonwealth water for the environment use was accounted at St George with over 127 GL flowing past the NSW-QLD border. We also accounted for almost 6 GL of Commonwealth environmental water in the Queensland Moonie, and almost 20 GL in the Queensland Warrego in 2021-22. It has been a bumper year for environmental water use and the outcomes that resulted.
A full listing of the use of unregulated entitlements in the intersection streams and Barwon-Darling can be found under the History tab.
What has environmental water achieved in the Northern Intersecting Streams and the Barwon-Darling?
Monitoring shows that environmental water in the Northern Intersecting Streams and the Barwon-Darling is supporting food, habitat, breeding and movement opportunities for many of the region’s unique plants and animals. It is also helping the system prepare for when dry conditions return.
A summary of preliminary results for 2021-22 are below with full monitoring reports available for each year.
Monitoring information is also provided by state governments and other organisations throughout the Northern Intersecting Streams and the Barwon-Darling.
- Following good rainfall, unregulated entitlements of Commonwealth water for the environment were utilised to protect natural river flows in the Lower Balonne, Warrego and Barwon-Darling rivers. In detail:
- In the Barwon-Darling, Commonwealth water for the environment helped to increase connectivity and support native fish movement and breeding early in the 21-22 water year.
- Flows in the Lower Balonne provided water to the internationally significant Narran Lake Nature Reserve for a third consecutive year, providing habitat for waterbirds breeding in significant numbers for the first time since 2012. Flows in the Condamine-Balonne including Commonwealth water for the environment also supported spawning and movement of golden perch in 2021-22.
- Commonwealth water for the environment from the Queensland Warrego in combination with natural flows in 2021-22 have continued to benefit the Toorale site, building on good flows in the last few years. Waterholes at Toorale are supporting vulnerable and listed international migratory bird species. Native plants on the Western floodplain at Toorale are in good condition. The Lower Warrego is also acting as a nursery for young golden perch.
- In the Moonie River, Commonwealth unregulated entitlements supported the aquatic ecosystems of the Moonie as well as reconnecting with the Barwon River.