Toorale Water Infrastructure Project

Management of March 2020 flow event

Significant rainfall at Bourke and surrounds in early March generated localised flows in the Warrego River. This flow, as well as local runoff, entered Boera Dam on Toorale shortly after. The event coincided with a flow in the Darling River.

In response, the National Parks and Wildlife Service opened the pipes at Boera Dam on 6 March 2020 so that water could flow down the Warrego River and into the Darling River. Because inflows exceeded the capacity of the existing pipes, water bywashed from Boera Dam into the Western Floodplain on Toorale, which is an area of significant ecological value. Flows across the western floodplain have also reach the Darling River for the first time in nearly a decade. The image below shows the first of the flow passing through the pipes at Boera Dam, looking downstream into the Warrego River. 

A larger flow event, generated by ex-tropical cyclone Esther, caused major flooding in the Queensland section of the Warrego River catchment. This flow entered New South Wales and flowed south through Toorale in mid-March. The peak rate and largest volumes reached Boera in late March.

The Darling River has now reconnected with the Murray River for the first time in 2 years. Productivity generated by the rain and river flows is now filtering through the river system carrying vital nutrients and food for the native animals and plants downstream.

The Commonwealth Environmental Water Holder expects to account for both its Warrego and Darling rivers water access licences acquired with Toorale to deliver environmental outcomes in both rivers.

The area around the junction of the Warrego and Darling rivers is part of Country for the Kurnu-Baakandji Aboriginal People. Toorale has extensive evidence of Aboriginal occupation and activity, including over 500 known Aboriginal sites. Artefacts recorded during 2018 have been dated at over 50,000 years old.

Toorale is associated with significant water management and engineering achievements including the Boera Dam and Floodwaters Scheme constructed by Sir Samuel McCaughey around 1892. This scheme was one of the most successful and large 19th century civil engineering and water management constructions known to be undertaken by a private individual in New South Wales.

The Warrego and Darling rivers and their floodplains on Toorale provide habitat for a diverse variety of wildlife and plants, including threatened species. When inundated with water, the wetlands along the floodplain spring to life supporting an abundance of native fish, frogs and waterbirds including pelicans, brolgas and the endangered Australasian bittern. The lush lignum that has established on the western floodplain provides some of the best habitat for waterbird breeding in the northern Basin. 

Studies have also highlighted the importance of the Warrego River for many of our native fish species. For example, the Warrego River is a significant source of golden perch to the Barwon-Darling system.

The Warrego River can also be particularly important for the Darling River and its dependent communities in years when inflows from other rivers are critically low.

More information on the natural values of Toorale can be found at Commonwealth Environmental Water Office: Looking after Toorale's wildlife and plants.

Extensive ecological monitoring has been undertaken at Toorale. Annual monitoring results are available for the Warrego River and floodplain and the Darling River in annual reports at Commonwealth Environmental Water Office publications and resources.

Monitoring such as this will improve knowledge to inform decisions about relative environmental demands on Toorale and the Darling River to help balance water use.

The Australian Government’s purchase of 25,498 megalitres (ML) of Toorale water entitlements, as transferred to the Commonwealth Environmental Water Holder, comprised:

• 17,826 ML in the Warrego River
• 7,672 ML in the Darling River

The available amount of water that can be used under licence varies from year-to-year according to rainfall, inflows and catchment conditions.

A summary of how CEWO has used its Toorale water licences since 2008 can be found at History – Northern Unregulated Rivers (Intersecting Streams and Barwon-Darling).

In addition to the water returned through the purchase of licences, the regulating structures on Toorale are now managed to pass more of the total Warrego River flow to the Darling River than has been the case in the past.

Toorale has extensive historic infrastructure that was initially built to regulate water across the property for agricultural purposes. This includes water storage dams along the Warrego River that have altered the natural flow patterns. At the time the NSW Government purchased Toorale, the main in-channel storages, starting from the upstream end of the Warrego River, were Boera Dam, Booka Dam, Homestead Dam and Peebles Dam.

Management of flows on and through Toorale is currently constrained by the capacity of pipes at each dam. Movement of native fish between the Warrego and Darling rivers is also affected by these dams, as they currently do not have fish passages on them.

When the flow down the Warrego River is larger than the capacity of pipes in Boera Dam, some water will spill onto the western floodplain. During larger flows, a portion of this water can return from the western floodplain to either the Warrego River or the Darling River. Similarly, if flows are larger than the capacity of the pipes at Peebles Dam at the bottom end of the Warrego River, water can back up and flow into Ross Billabong rather than down the Darling River.

When Toorale was purchased, the NSW and Australian governments agreed to 'demolish, remove, modify or decommission water infrastructure (on Toorale) to improve water flows for environmental purposes'. The Toorale Water Infrastructure Project is being undertaken to achieve this.

Such modifications to the infrastructure will give greater flexibility to share water between Toorale and the Darling River depending on relative needs, thus improving water flows for environmental and other purposes.

The Project aims to ensure that the important values of Toorale are maintained or enhanced, while achieving greater flexibility to pass more water to the Darling River in certain circumstances.

The Project objectives include:

• increase the maximum flow rate than can be delivered to the Darling River
• retain the capacity to divert flows from Boera Dam to the Western Floodplain
• maintain or improve the ecological values and processes for the Warrego and Darling rivers and connected floodplains
• improve fish passage connectivity between the Warrego and Darling Rivers
• minimise impacts to Aboriginal cultural heritage and support the recognition and maintenance of Aboriginal cultural values
• consider social and stakeholder values in the development of options, including adjacent and downstream stock and domestic water access
• minimise impacts to public road access and park operations
• consider recreational and aesthetic values.

The Project will be done in 2 phases:

Phase 1 – Removal of Peebles Dam (complete as of October 2019)

• • Peebles Dam is the most southern dam on Toorale.
• The project removed a section of the Peebles dam bank across the Warrego River to enable flows to pass unimpeded to the Darling River.
• More information on Phase 1 can be found on the Project’s review of environment factors webpage.

Phase 2 – Modifications to Boera, Booka and Homestead dams

• Boera Dam will have  gated culverts installed. The gates can be operated to either pass flow downstream in the Warrego River or out to the western floodplain, or a combination of both. The new structure will increase the capacity to pass flows down the Warrego from around 600 ML/day to potentially 1650 ML/day.
• Homestead and Booka dams will be modified to pass additional flow downstream by a ‘fill and spill’ arrangement. These structures will not require any active operation to pass inflows.
• Homestead Dam is currently breached and will be repaired as part of the project.
• Fishways to allow fish passage will be constructed at the three dams being modified so that fish can migrate upstream and downstream along the Warrego River (and into the Darling River). 
• More information on Phase 2 can be found on the Project’s public consultation webpage.

Information on the current process for managing the Commonwealth environmental water holdings at Toorale can be found at Commonwealth Environmental Water Office: Portfolio Management Plan - Northern Unregulated Rivers, 2019–20.

The new structures will allow for greater flexibility to meet the water needs of the environment and, in certain circumstances, downstream communities.  The proposed operating rules will prioritise flows to the Darling River when conditions are critically dry, while supporting floodplain values during higher sustained flows in the Warrego River or when the Darling River is flowing well.  

The new fishways will be operated to support fish movement between the Warrego and Darling Rivers during all flows.

The new structures and rules will be subject to approval from relevant government agencies.

The Project has engaged the Aboriginal community (represented by the Toorale Joint Management Committee), local landholders, downstream water users and representatives from local, state and Australian government departments. The proposal has been adjusted several times in response to issues raised and information provided.

Phase 1 of the project, the removal of Peebles Dam, commenced in early October as planned. It was completed ahead of schedule, on 29 October 2019. See time lapse footage of the dam removal below.

The detailed designs for Phase 2 are being finalised. The environmental assessment was on public exhibition in January and February 2020 and a number of submissions were received. Pending approvals, the works will commence in 2020 and are due for completion in 2021.

Public exhibition closed in February 2020. However, you can contact the project team at any time through the Department of Planning Industry and Environment, Environment, Energy and Science group at toorale.project@environment.nsw.gov.au.

If you’d like to be added to the mailing list for possible site visits and/or updates, please email toorale.project@environment.nsw.gov.au.