Northern Unregulated Rivers
The northern unregulated rivers region includes the Barwon-Darling, the Condamine-Balonne, the Moonie, the Warrego and Border Rivers. These catchments are predominantly unregulated systems in which the majority of water use occurs by diversion of river and overland flows (water that breaks out of a watercourse as floodwater or runs across the land after rainfall) during episodic flow events. Water taken from unregulated sources is often stored in large, shallow floodplain storages known as ‘ring tanks’ or ‘turkey nest’ dams. These can range from 100’s of megalitres to several hundreds of giglitres in capacity.
The region includes many significant wetlands, including Wetlands of International Importance listed under the Ramsar Convention (Ramsar) and nationally important wetlands listed under the Directory of Important Wetlands in Australia (DIWA). Some of these wetlands include:
- Narran Lakes (Condamine-Balonne) (Ramsar)
- Currawinya Lakes (Ramsar)
- Paroo River Wetlands (Paroo River).Ramsar)
The Barwon-Darling River flows in a south-westerly direction from the north-east region of the NSW-QLD border. The catchment includes the Barwon River from Mungindi to the confluence of the Culgoa River near Brewarrina (where the Barwon becomes the Darling River) and the Darling River to the Menindee Lakes. The Darling River drains Queensland's Darling Downs via the Condamine-Balonne and Warrego rivers. This catchment is representative of a large Australian dryland river system. Key characteristics include its low gradient and large floodplain, climatic variability and arid to semi-arid conditions.
Covering 45,510 km2 or 4.4 per cent of the total area of the MDB, the Barwon-Darling catchment is bounded to the west by the Bulloo catchment and receives flow from the Paroo, Warrego and Condamine-Balonne rivers in the north and west, and the Moonie, Border Rivers, Gwydir, Namoi and Macquarie-Castlereagh Rivers to the east. While the Barwon-Darling River itself is unregulated, many of its tributaries are regulated.
The Barwon-Darling catchment is an ecologically significant area because it includes:
- wetlands along the river such as Wongalara Lake, Poopelloe Lake, Lake Woytchugga, Acres Billabong, Talyawalka Anabranch and Teryawynia Creek wetlands and several deflation basin wetlands (geological depressions formed by erosion when soil is shifted by the wind)
- major waterbird breeding habitat sites at lakes and other wetlands along the floodplain which are watered at a variety of flows
- the Barwon-Darling River channel and associated riparian habitats which support a wide variety of ecosystems and a number of fish species, including bony herring and golden perch
- a diverse range of flora species, including river red gum, black box, river cooba, coolabah and lignum
- fauna including species listed under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) such as Murray cod, Latham's snipe, rainbow bee-eater and superb parrot, and the NSW Threatened Species ACT 1995 (TSC Act) such as the blue-billed duck, the brolga and the grey falcon.
The Barwon-Darling River channel supports a wide variety of wetland types which vary along the river, and include anabranches, flood runners, billabongs, basins and swamps. The region also includes the significant environmental asset, Talyawalka Anabranch and Teryawynia Creek (listed as nationally important in the Directory of Important Wetlands in Australia). This site comprises the wetlands of the Talyawalka Anabranch of the Darling River and its tributary, Teryawynia Creek. These wetlands include numerous intermittent wet and dry lakebeds and are representative of a semi-arid inland floodplain wetland system. When inundated, the lakes provide habitat to more than 10,000 waterbirds.
The Condamine-Balonne region is mostly in southern Queensland, and is based around the Condamine and Balonne rivers. Spanning the high country in the east to the wide alluvial western plains of the lower Balonne catchment, the topography contains distinct tablelands, slopes and plains landforms. Nearly two-thirds of the region is comparatively flat. It rises in the Great Dividing Range near Warwick, is bounded to the west by the Warrego region, the south by the Border Rivers, Moonie and Barwon-Darling regions.
The Condamine-Balonne catchment covers 150,101km2 or 14.4 per cent of the MDB area. Tributaries include the Maranoa River which flows southward from the Carnarvon Range into the Beardmore Dam (capacity 82 GL) near St George. The main dam on the Condamine River is the Leslie Dam (capacity 106 GL). The Nebine Creek in the west of the region flows in a southerly direction and joins the Culgoa River in northern New South Wales upstream of Collerina. The catchment flows discharge either to the Barwon River (via the Culgoa and Bokhara rivers) or to the terminal lakes and wetlands of the Narran River.
The catchment is an ecologically significant area because it includes:
- several wetlands listed on the Directory of Important Wetlands in Australia (DIWA)
- endangered ecological communities including Brigalow-gidgee Woodland/shrubland in the Mulga Lands and Darling Riverine Plains Bioregions
- a diverse range of flora and fauna including lignum, river red gum woodland, straw-necked ibis and native fish
- species listed as vulnerable under state legislation including silver perch, freckled duck and Australian painted snipe, and under the EPBC Act including the great egret, cattle egret and Murray cod
- habitat for wetland-dependent species
- migratory bird habitat.
Wetlands of national importance in the catchment include Great Artesian Basin Springs, Lake Broadwater, The Gums Lagoon and Dalrymble and Blackfellow Creeks.
The Lower Balonne area (a complex floodplain channel system) supports the largest number of wetlands in the MDB and also hosts a number of nationally significant wetlands including the Ramsar-listed Narran Lake Nature Reserve. The Narran Lakes system comprises a series of interconnecting terminal drainage lakes (Back, Clear and Narran lakes) and wetlands of the Narran River that flow from the Balonne River. Part of the area comprises the internationally important, Ramsar-listed Narran Lake Nature Reserve. The lakes are one of the most important waterbird breeding habitats in eastern Australia, particularly for the straw-necked ibis.
Another wetland listed on the Directory of Important Wetlands in Australia (DIWA) is the Culgoa River Floodplain, which supports a significant area of coolabah woodlands. It is listed for the significance of its terrestrial floodplain vegetation including the large area of remnant coolabah woodlands. The Culgoa National Park in this area has high plant diversity with a low percentage of exotic species.
The Moonie Catchment is located predominantly in south-western Queensland and extends over the border into northern New South Wales. It is bounded to the east by the Border Rivers region, to the north by the Condamine-Balonne and to the south by the Barwon-Darling region. The catchment is essentially flat with low relief hills scattered throughout the floodplains of the Moonie River.
The catchment covers an area of 15,103km2 or 1.4 per cent of the MDB. It is one of the most heavily cleared in southern Queensland. From its headwaters east of Tara, the Moonie flows in a south-western direction and is joined by tributaries such as Teelba, Brigalow and Toombilla Creeks. It is an unregulated river, yet almost all irrigation in the area depends on surface water.
The Moonie catchment is an ecologically significant area because it includes:
- a major bioregion, the Southern Brigalow belt, with remnants of brigalow forests, poplar box, wilga and white cypress pine
- protected species including the Australian painted snipe, the freckled duck and the purple-spotted gudgeon
- a diverse range of flora and fauna, including river red gum, coolabah, lignum and black box vegetation communities, and fish communities including olive perchlet, bony bream, gudgeons, golden perch and freshwater eel-tailed catfish
- three endangered vegetation communities
- over 100 wetlands exceeding one hectare in area, many of which support bird breeding events
- high biodiversity and unique systems in-stream
The Thallon waterholes have been identified as a significant ecological site in the Moonie catchment. They are filled by overbank flows from the Moonie River during significant flow events. This wetland comprises two lakes of approximately 12 ha and 21 ha, and is a relatively permanent source of water. These act as refugia for organisms and have been recorded to support between 10,000 and 20,000 waterbirds.
The Warrego Catchment is predominantly in Queensland and spans the area from the Carnarvon Range at the northernmost point of the Murray-Darling Basin to the Darling River in northern New South Wales. It is bounded to the east by the Condamine-Balonne region, to the west by the Paroo region and forms the northern edge of the MDB. The region is generally flat with a gentle southwards gradient. The upper catchment of the Warrego River includes the Warrego and Chesterton ranges.
It covers a total area of 87,749km2, or 8.4 per cent of the Murray-Darling Basin. Tributaries to the Warrego include the Nive and Langlo Rivers. The Warrego River enters the Darling River downstream of Bourke, and during times of flood is connected to the Paroo River via Cuttaburra Creek. This system is one of the last unregulated systems in the MDB.
The Warrego catchment is an ecologically significant area because it includes:
- a wide variety of vegetation including native grasslands, saltbush shrubland, mulga woodlands and shrublands, brigalow and eucalypt stands
- one of the only places where silver perch breed naturally
- a diverse range of other fish communities including bony herring, golden perch and Australian smelt
- species listed under the NSW Threatened Species ACT 1995 (TSC Act) including Major Mitchell's cockatoo and brolga
- wetlands covering a total area of approximately 345,000 ha which are of critical importance to waterbird populations of the MDB.
Many wetlands in the Warrego River catchment are recognised as being of national importance; the two which have been most extensively researched are Yantabulla Swamp and the Warrego River Waterholes.
Yantabulla Swamp is part of the Cuttaburra Basin system, which is filled from various sources including Cuttaburra Creek and Paroo River overflow. The swamp covers over 37,000 ha and has been identified as the most important waterbird breeding site in north-west NSW. The main vegetation communities are cane grass, lignum, fringing yapunyah, river red gum, coolabah and river cooba.
The Warrego River Waterholes are a string of large permanent and intermittent waterholes covering some 500 ha along the river channel in Queensland. These sites are flooded seasonally in most years. They provide an invaluable habitat and refuge for a wide range of aquatic fauna including species listed under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) such as Murray cod. Significant waterbird populations are known to inhabit the waterholes particularly during periods of high flows.