National Water Commission

The Condamine-Balonne WMA covers the most upstream reaches of the Murray-Darling Basin. It incorporates the catchments of the Condamine and Maranoa Rivers as well as the Balonne, Culgoa and associated rivers from their confluence to the New South Wales border. The WMA includes three Water Supply Schemes: the Upper Condamine, Maranoa and St George Water Supply Schemes. While the Water Resource Plan (WRP) for the area was completed in 2004, the Resource Operation Plan is currently under development.

This area also covers two groundwater areas: Eastern Downs and Eastern Downs Ground water management area GMUs with the remainder of the area overlying the Great Artesian Basin GMU.



Figure 1 Condamine-Balonne water management area locality map

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Management of Water Supply

Natural Resources and Water (QNRW) is the licensing authority responsible for un-supplemented surface water diversions and groundwater extractions. They develop and manage the Water Resource Plans and Resource Operation Plans [http://www.nrw.qld.gov.au/wrp/index.html].

Sunwater manages the regulated supplemented water in the Condamine-Balonne along with water harvesting within the declared areas. As the ROP is currently under development, SunWater manages the water supply schemes under Interim Resource Operation Licenses (IROLs) issued by QNRW.

Local Government is responsible for retail water supply, the majority of which is sourced from SunWater. Toowoomba City Council lies within the Condamine-Balonne catchment but owns and manages the Perseverance and Cressbrook Dams within the Moreton catchment, as well as Cooby Dam within the Condamine-Balonne. Toowoomba City Council transfers water out of the Moreton WRP area, treats it and then delivers it to surrounding councils in both the Moreton and Condamine-Balonne catchments, with the majority discharged to the Condamine-Balonne.

Management of Waterways

The Condamine-Balonne WMA has a highly variable subtropical climate. Annual average rainfall varies significantly over the catchment with a strong rain shadow covering much of the Eastern Downs in the lee of the Great Dividing Range. The majority of rain falls through the summer with drier winter months (Figure 3).

The long term average annual rainfall over the region is 579 mm and the 2004-05 period rainfall for the region was 534 mm (Figure 2). The rainfall for the 2004-05 year was 92% of the long term average and the 10 year average was about average at 103% of the long term average. The total evapotranspiration was 522 mm (BRS, 2006) in 2004-05 (Table 1).

Table 1 Summary of Condamine-Balonne water management area contextual information

Figure 2 Annual rainfall for the Condamine-Balonne water management area (modified from BOM, 2006)




Figure 3 Monthly rainfall and evaporation for the Condamine-Balonne water management area (modified from BOM, 2006 & Climate Atlas)




Figure 4 Representative streamflow hydrograph for the Condamine-Balonne water management area for Maranoa River At Cashmere (gauge 422404A)

Summary of the total water resources in the basin

Table 2 Summary of water balance for Condamine-Balonne water management area, 2004-05

Figure 5 Water balance summary for Condamine-Balonne water management area

Outcomes from the water cycle report

The following information becomes apparent from Table 2.

• The surface water available in storage was about 23% less at the end of 2004-05 than at the start (no data for groundwater).
• There was a large surface water error term (-50%), likely due to the extremely large runoff figure.
• The groundwater error term was 21%, due to the absence of groundwater opening and closing volumes.
• The water balance was dominated by runoff and recharge and ET, with the total diversions and extractions making up only 18% of total runoff and recharge volumes.
• No estimate of surface water runoff or groundwater recharge was available for the system for the 2004-05 period. QNRW was not able to review the Water 2010 data to a sufficient level. Due to the sensitive nature of community consultation over the forthcoming ROP, QNRW was not comfortable with the use of the Water 2010 data to estimate these values. However, in the absence of other estimates, this data was used.
• Inflows to the Condamine system were distributed throughout the system.
• Water used in the Condamine – Balonne was sourced equally from groundwater and surface water resources.
• Only 2% of surface water runoff was discharged to the lower reaches of the Murray-Darling Basin.
• Water use was predominantly for irrigation in the catchment as there are few urban areas.
• The interaction between surface water and groundwater was not quantified in this balance.
• Data could not be obtained for the following items in the water balance:
• Onstream and offstream minor catchment and farm dams
• Groundwater storage volumes (renewable and non-renewable)
• Soil - unsaturated zone storage volumes
• River channels storage volumes
• Groundwater to surface water flow (baseflow)
• Groundwater discharge to springs
• Irrigation drainage returns and irrigation channel outfall returns
• Groundwater system gains
• Self-extracted water from minor catchment dams
• Losses from minor catchment dams
• Conveyance losses (seepage from channels)
• Seepage from streams to groundwater
• Evaporation from major storages
• Environmental releases
• Aquifer re-injection / extraction for re-injection
• Self extractions from groundwater
• Aquifer flow in/out of entity
• Groundwater extraction to outside of entity

Download 2004-05 water cycle report: