National Water Commission

The Macquarie River is located within the Murray-Darling Drainage Division in central New South Wales. Although the complete Macquarie River catchment includes regulated and unregulated areas, only the regulated area was assessed for the water balance.

The Macquarie River is a tributary of the Barwon River, which in turn is a tributary of the Darling River. It has several tributaries, including the Bell, Cambells and Fish Rivers and there is complex system of anabranches and creeks in the lower catchment that connect the Macquarie River with the Bogan and Darling Rivers. The Macquarie Marshes are located in the north-east corner of the catchment and the Macquarie River does emerge from the wetlands before being joined by the Castlereagh River and then flowing into the Barwon River near Brewarrina. The Bogan River rises in the Harvey Ranges between Parkes and Peak Hill and flows northwest through a broad, flat landscape through Nyngan to join the Darling River near Bourke.

Irrigation within the Macquarie River – Regulated WMA includes private irrigation as well as several irrigation schemes (Narromine - Trangie, Buddah Lakes, Tenandra, Trangie – Nevertire, Nevertire and Marthaguy). There are two primary water storages within the study area, Burrendong and Windamere Dams. Major towns in the area include Dubbo, Wellington and Mudgee.

The Department of Natural Resources (DNR) is the licensing authority and manages both surface and groundwater diversions for urban, commercial/industrial, irrigation and environmental purposes. The Central West CMA is responsible for managing the native vegetation, soil and other natural resources in the catchment in conjunction with the community, local government, industry and State Government. State Water [http://www.statewater.com.au] manages the major water supply storages in New South Wales and supplies bulk water to the irrigation authorities, town water supply authorities, mines, electricity generators and other industry by releasing water from its dams into rivers to be accessed by downstream water users. State Water also delivers water for private irrigators and stock and domestic users and is responsible for delivering environmental flows, in accordance with rules as set out in NSW Water Sharing Plans, on regulated rivers in the state. Local councils treat the bulk water and deliver it to urban users in the major towns within the catchment as well as managing the wastewater collection and treatment network (e.g. Dubbo City Council).



Figure 1 Macquarie River - Regulated water management area locality map

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Rainfall across the Macquarie River - Regulated WMA was below average in 2004-05, at around 91% of long term average rainfall, however the 10 year average was 106% of the long term average (see Figure 2). In the history of its irrigation system, by June 2005, the Macquarie Valley had the lowest allocations and water deliveries (State Water, 2006).

Table 1 Summary of the Macquarie River - Regulated water management area contextual information

Figure 2 Annual rainfall for the Macquarie River - Regulated water management area (modified from BOM, 2006)




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




Figure 4 Modelled pre development streamflow hydrograph for the Macquarie River - Regulated water management area for the Macquarie River at Dubbo (site 421001)




Figure 5 Modelled pre development streamflow hydrograph for the Macquarie River - Regulated water management area - Macquarie River at Burrendong Dam (site 421078)




Figure 6 Representative bore hydrograph for the Macquarie River - Regulated water management area (Bore name: Dubbo)

Summary of the total water resources in the basin

The total volumes of water available and supplied from water resources in the Macquarie River – Regulated WMA are shown in Table 2

Table 2 Summary of water balance in the Macquarie River - Regulated water management area, 2004-05

Figure 7 Water balance summary diagram for Macquarie River - Regulated water management area

Outcomes from the water cycle report

The following information becomes apparent from Table 2.

• The water balance was completed for the regulated area of the Macquarie River catchment. There was a large amount of data available, including detailed modelling, for the regulated area, and hence the data quality for this water balance was relatively high. However, the balance may be misleading without considering the entire hydrological catchment (i.e. the combined regulated and unregulated areas). This is an opportunity for improvement in future assessments.
• The error in the water balance was 0%. This was due to the unaccounted for flows being incorporated with other items in the water balance. For surface water the balancing item was ‘Other losses’, the groundwater balancing item was the closing storage volume. Other jurisdictions reported unaccounted flows as an error term.
• The water balance was dominated by rainfall, groundwater extractions, surface water diversions and losses.
• Water use within the regulated area was predominantly for agriculture as there are few urban areas in the WMA. Additionally there was a significant volume of environmental flow in the WMA.
• The Macquarie Marshes are a significant ‘user’ of environmental water as a large amount of evapotranspiration occurs in these wetlands.
• Water used in the regulated area was sourced equally from groundwater and surface water resources in 2004-05. It should be noted that water use in this catchment from groundwater sources may be higher during periods of drought (as in 2004-05); however it is likely to revert back to predominantly surface water supply when surface water resources are available.
• The interaction between surface water and groundwater (predominantly seepage from streams to groundwater) was 16,000ML in 2004-05, or 4% of the total captured rainfall (sum of runoff and recharge).
• There was a very slight decrease in the amount of water in storage over 2004-05.
• The volume of on farm storage in farm dams / minor storages may be significant; however there was no data available at present on volumes in storage or used.
• The volume of groundwater stored was estimated by DNR by calculating the volume in the aquifer(s) to a depth of 20m below the ground surface (assuming a saturated thickness, estimating the water table drawdown depth from bore levels, and using the area and aquifer porosity). For the Macquarie River – Regulated area, the volume of groundwater at the end of the year was determined from the volume at the start of the year plus any unaccounted for groundwater errors (i.e. it has been used as the balancing item).
• Data could not be obtained for the following items in the water balance:
• Minor catchment dams (may be a large part of the water balance).
• Soil - unsaturated zone storage volumes
• Urban treated effluent (returns to the river)

Download 2004-05 water cycle report: