For the last decade, the CEWH has funded river and floodplain wetland monitoring and research in the Warriku-Baaka (Warrego-Darling) Rivers and catchment (Figure 1). This work is part of the larger Flow – Monitoring, Evaluation and Research (Flow–MER) program that spans the entire Murray-Darling Basin.
The Warriku-Baaka (Warrego-Darling) Selected Area (Selected Area) is located around 80 km south-west of Bourke in northwestern NSW, and is contained within the boundary of the Toorale National Park and State Conservation Area (Figure 1). The Baaka (Darling) River catchment drains the north westerly portion of the MDB. Most of its tributaries (Macquarie, Castlereagh, Namoi, Gwydir, Macintyre and Condamine-Balonne Rivers) drain the Great Dividing Range in northern New South Wales and southern Queensland. In contrast, the Warriku (Warrego) catchment drains more arid and flat areas to the north of the Selected Area. The Warriku River only flows intermittently during periods of high rainfall in its upper catchment, usually manifesting downstream as slow-moving freshes and floods. Within the Selected Area, the Warriku River winds its way south to the Baaka River. It is bordered to the west by an extensive floodplain system known as the Western Floodplain (Figure 2).
The CEWH implemented the Long-term Intervention Monitoring (LTIM; 2014-2019) and the Flow-MER (2019-2024) programs in this area to evaluate the outcomes of Commonwealth water for the environment delivery. This story explores some key learnings since monitoring began in the Warrego-Darling Selected Area spanning times of severe drought (2018-20) to significant floods (2021-22; Figure 2).
From 2014 to late 2019 conditions were generally dry, and water quality suffered due to a lack of flow, resulting in disconnected pools and channels. Occasional rainfall promoted small natural flows, and Commonwealth water for the environment releases supported some frog and fish recruitment, before drought conditions reached extremes in 2017-2019 (Figure 3). In this period, the Warriku and Western Floodplains disconnected completely, and monitoring saw a transition in floodplain vegetation from a wet phase to a dry phase, with terrestrial species taking over.
The composition of inland floodplain vegetation communities, such as those on the Western Floodplain, fluctuates as the area alternates between wet and dry periods. Water loving species dominate wet periods, but as the floodplain dries these species die off, creating space for terrestrial species to move in.
Beginning in 2021, significant flows caused inundation across the Selected Area (Figure 4). Commonwealth water for the environment helped to extend this inundation into 2023 which resulted in the Western Floodplain shifting back to a wet state and biodiversity boomed. These favourable conditions sustained the growth of wirnta (lignum; Figure 6), coolibah seedlings and saplings, and promoted coolibah and blackbox flowering and seed development. Hyrtl’s tandan catfish (Figure 7) were observed at their highest abundance since 2016. Waterbird species richness, density and diversity was increased. Murray River turtle hatchlings were observed in Boera Dam in February 2023.
Sespite the wet conditions it was not all good news. Native fish species such as Murray cod and silver perch, which are expected to exist and flourish in the Selected Area, are in such small numbers that sampling efforts could not detected individuals on a regular basis. For these species to occupy the reaches of the Selected Area once again, re-stocking in combination with habitat restoration and good flow conditions will be needed.
The 2023-24 water year began with dry conditions which persisted until late February 2024. Water quality was especially poor in early 2024, with some monitoring sites having algal blooms as a result of high water temperatures and low dissolved oxygen. These conditions improved following the commencement of a sustained flow through the Area in January 2024, and heavy rainfalls in April and May 2024. Resulting inundation made some sites inaccessible for the Autumn surveys. Fish surveys saw the capture of some significant species, including 100-200 mm long golden perch and Hyrtl’s tandan in the Warriku.
The Selected Area has displayed distinctive wet and dry phases over the decade of monitoring. Throughout each phase, informed water for the environment releases helped maintain or extend hydrological connectivity between the Warriku and Baaka Rivers and the Western Floodplain. In doing so, these releases benefitted various flora and fauna species (Figure 8 and 9).
These learnings about the ecological processes occurring in the Junction of the Warrego and Darling Rivers Selected Area and how water for the environment can be used to aid these processes will inform continued adaptive management.
The Warriku-Baaka is a unique and diverse system that supports a rich diversity of plants and animals in a constantly changing environment. Our work here is to collect data, monitor ecosystem interactions and evaluate our findings so we can provide accurate and reliable information to the Commonwealth Environmental Water Holder for the effective management of environmental water.
The information on this website is presented by the Department of Climate Change, Energy, the Environment and Water (the Department) for the purposes of disseminating information to the public. It does not constitute legal or other professional advice.
The views and opinions expressed on this website are those of the authors and do not necessarily reflect those of the Australian Government or the Portfolio Ministers for the Department or indicate a commitment to a particular course of action.
While reasonable efforts have been made to ensure that the contents of this website are factually correct, the Commonwealth of Australia does not accept responsibility for the accuracy or completeness of its contents. The Department disclaims liability, to the extent permitted by law, for any liabilities, losses, damages and costs arising from any reliance on the contents of this website. You should seek legal or other professional advice in relation to your specific circumstances.
Use of this website is at a user’s own risk and the Department accepts no responsibility for any interference, loss, damage or disruption to your computer system which arises in connection with your use of this website or any linked website.
The Flow-MER program team acknowledge and respect the Traditional Owners as the First Peoples of the lands and waters of the Murray Darling Basin.
We recognise their unique ability to care for Country and their deep spiritual connection to it. We honour Elders past and present whose knowledge and wisdom has ensured the continuation of culture and traditional practices.
We are committed to genuinely partner, and meaningfully engage, with Traditional Owners and Aboriginal communities to support the protection of Country, the maintenance of spiritual and cultural practices and their broader aspirations in the 21st century and beyond. In particular we acknowledge the Traditional Owners of the seven Selected Areas where Flow-MER research is focussed.
Artwork credit: Wiradjuri Artist Rebecca Salcole
Artwork credit: Wiradjuri Artist Rebecca Salcole
The Goulburn River is known by several names as it travels first through Taungurung country in the hilly upper and middle reaches. Here, the river is called Waring.
As the river meanders downstream of Murchison and into the northern flatlands, the river winds through Yorta Yorta country and is called Kaiela, meaning ‘father of waters’. Eventually, the river flows to a confluence with the River Murray near Echuca. This confluence of rivers is known as Koninner.
We acknowledge and respect the Traditional Owners of the country this story has been written about, Taungurung and Yorta Yorta, and all the countries through which the Goulburn river flows. This story was written on Ngunnawal country. Sovereignty was never ceded, and we pay our respects to elders past, present and emerging.