Intersecting Streams catchment

Water managers will optimise the outcomes of recent flows with a focus on creating opportunities for northern basin recovery.

Small tufts of grasses and reeds showing above the lake waters with blue sky in the background in Narran Lake Nature Reserve when it was in flood in April 2021

The Intersecting Streams cover an area of approximately 120,431 square kilometres. This area comprises the NSW sections of 4 key river systems: the Paroo, Warrego, Culgoa–Birrie–Bokhara–Narran connected system and Moonie River that originate in Queensland and terminate in New South Wales.

There are 3 listed Ramsar sites and areas indicated in the Directory of Important Wetlands located in the Paroo, Warrego and Narran water sources and an Important Bird Area (IBA) identified by BirdLife Australia.

Traditional Owner groups in the Intersecting Streams area include Budjiti, Euahlayi, Guwamu/Kooma, Kamilaroi, Kunja, Murrawarri and Ngemba.

Water for rivers and wetlands

The Intersecting Streams rely on rainfall in southern Queensland and connection across the NSW–Queensland border to generate the flows that support rivers and wetlands in this area.

The region saw average to slightly above average rainfall in mid-2021. This was followed by above to well above average rainfall from late 2021 to early 2022. This rainfall created periods of high flow across the Intersecting Streams, with notable flows up to 8229 ML per day in the Paroo (at Willara gauge), 8014 ML per day in the Culgoa (at Collerina gauge) and 3079 ML per day in the Narran (at Narran Park). This rainfall generated significant flow to Narran Lakes and the Paroo and Bulloo river wetlands.

With drought in the northern basin having eased, critical environmental demands have reduced, particularly in relation to connectivity. In 2022–23, the focus of water managers will shift to recovery and maintaining current catchment conditions where possible.

Weather and water forecast

The El Niño–Southern Oscillation (ENSO) outlook remains at La Nina, with a return to neutral ENSO during winter. Rainfall was below average and temperatures warmer than average in May and June 2022 for eastern mainland Australia, including the Intersecting Streams catchment, and this will continue in July.

Water availability is predicted to be higher than average. Commonwealth unregulated licenses are likely to be triggered with potential for protection of flows in the Warrego, Culgoa and Narran. Flows may be directed to the Western Floodplain at Toorale with the recently modified regulator at Boera allowing for more effective management of flows.

Water managers have prepared annual watering plans that consider a range of weather and water availability scenarios. This is known as resource availability scenario planning. There remains a significant degree of uncertainty around resource availability. On balance, the outlook is rated as ‘wet to very wet’.

1. ENSO: The interaction between the sea surface and atmosphere over the Pacific Ocean which results in dryer or wetter conditions (El Nino or La Nina).

Resource availability scenario

 Dry river reaches in lower Mehi near Collarenebri gauge 2

Very dry

Main aim: Protect

Avoid critical loss
Maintain key refuges
Avoid catastrophic events

 Red Gum, "Hells Gate", now called "Black Rocks", Darling River

Dry

Main aim: Maintain

Maintain river functioning
Maintain key functions of high priority wetlands

 Macquarie River Trail, Dubbo

Moderate

Main aim: Recover

Improve ecological health and resilience
Improve opportunities for plants and animals to breed, move and thrive

 Lower Murray

Wet to very wet

Main aim: Enhance

Restore key floodplain and wetland linkages
Enhance opportunities for plants and animals to breed, move and thrive

Key planned actions for 2022–23

 

Waterbird icon

Waterbirds

In 2022–23, water is likely to be retained in Narran Lake as a result of inflows which commenced in late 2021. A priority is to ensure adequate vegetation condition and water level should further inflows trigger another colonial waterbird breeding event in spring 2022.

Native fish icon

Native fish

A key priority for water managers is to support stocks of native fish and provide opportunities for them to breed and disperse into secure habitats.

Native vegetation icon

Vegetation

The water that reached the Narran Lakes in late 2021 and early 2022 is expected to have further improved vegetation condition in the lakes system following flows that replenished the lakes in early 2021. Water managers will prioritise opportunities that arise in 2022–23 to increase the duration of inundation of water- dependent vegetation.
In mid-2021, flows in the Warrego River inundated vegetation communities on the Toorale Western Floodplain wetland, and they were further inundated in late 2021 and early 2022. Repeated inundation in 2022–23 will increase vigour and diversity of wetland vegetation in this location.

Connectivity and water flow icon

 Connectivity

As these systems are typically intermittent, further flows and inter-system connections depend on rainfall occurring throughout the year.

Figure 1 Map of proposed annual priority targets in the Intersecting Streams Resource Plan area 2022–23.

Map of the Intersecting Streams Water Resource Plan area 2022–23

With a series of unregulated NSW rivers fed from Queensland, watering actions in the NSW portion of the Intersecting Streams area cannot be managed in the same way that water for the environment can be managed in other regulated systems. Environmental outcomes are typically generated by managing water for the environment through systems and reducing the volume of water that can be taken from rivers.

The NSW Government works with the Commonwealth Environmental Water Holder to manage water in the catchment. 

First Nation objectives in the catchment are outlined in the Aboriginal Environmental Water Priorities.


Water for the environment is a share of the water in dams and rivers that is set aside to support the long-term health of local rivers, creeks and wetlands. Healthy rivers carry water to homes, farms, schools and businesses. Rivers and wetlands are important cultural and spiritual sites for Aboriginal people, as well as the broader community.


Source

Maximum volume available
(megalitres – ML)

Volume expected 1 July under current conditions (megalitres – ML)

Water licenced to the Commonwealth

 

Moonie

 

 

Queensland unsupplemented

5,671 ML

Event-dependent

Condamine-Balonne

 

 

Nebine unsupplemented

5,920 ML

Event-dependent

Lower Balonne unsupplemented

68,317 ML

Event-dependent

Condamine-Balonne unsupplemented

1,062 ML

Event-dependent

Condamine-Balonne overland flow

 96,741 ML

 Event-dependent

Upper Condamine unsupplemented

 841 ML

Event-dependent

Upper Condamine groundwater

 40,221 ML

N.A.

St George (medium)

 45 ML

0 ML

Warrego

   

Queensland unsupplemented

39,445 ML

Event-dependent

New South Wales unregulated

17,826 ML

Event-dependent

Notes: This is an indicative summary of expected volumes to be available. For further detail and information on available volumes please contact the region via Department of Planning and Environment enquiries on 1300 361 967.

1 gigalitre = 1000 megalitres; 2.5 megalitre = 1 Olympic swimming pool.