The type of usage (urban, hydroelectric, agriculture) did not alter the level of information available, although the level of development usually correlated with the level of information available for those areas. Low levels of development generally coincided with lower levels of data and information availability as more investigations occur in the highly developed regions.

The key points to note are:

Capital cities show up as “over-developed” due to the fact that most are dependent on transfers in for supply (i.e. the recharge and runoff within the water balance area does not meet the demand);
Data availability and reliability closely mimics the water utilisation factor which reports the level of development of the available resource;
Several of the over-developed areas are due to groundwater resource development which is either not licensed (e.g. petroleum wells) or does not include some of the use types in the extraction licensing process (e.g. stock and domestic bores);
Nearly all the water balance areas are either highly or over developed in relation to the available recharge and runoff in the water balance area. This is mainly due to the way in which the water balance areas were selected as the level of development was one of the primary criteria for selection.

Summary of outcomes from water balances

WMA Name	Level of Groundwater / Surface water Interaction	Water Utilisation Factor	Data reliability and availability factor	Other Comments
New South Wales
Gwydir Regulated	Low	Moderate	Medium	Highly developed area; higher than average rainfall for 2004-05
Richmond	n/a	Low	Medium	Major water use is for urban water supplies.
Namoi River – Regulated	Low	Moderate	Medium	Highly developed area; higher than average rainfall for 2004-05
Macquarie River – Regulated	Moderate	Moderate	Medium	Highly developed area;
Hunter River – Regulated	Moderate	Moderate	Medium	Highly developed area; higher than average rainfall for 2004-05
Lachlan River – Regulated	High	Moderate	Medium	86% of water used was sourced from groundwater but would normally be surface water
Murrumbidgee River – Regulated	Moderate	High	Medium	18% returns from irrigation. Significant surface water inflows from other entities. Larger transfer out due to the Snowy Hydro Scheme.
Northern Territory
Daly River	Low	Low	Low	Environment’s share was 95% of flow in Daly River
Goyder River	Moderate	Low	Low	Environment’s share was 99% of flow in Daly River
Roper River	High	Low	Low	Environment’s share was 99% of flow in Roper River
Ti Tree	High	Low	Low	Though inflow equals outflow, the selected hydrograph shows water levels declining.
Mereenie Sandstone	n/a	Over-developed	Low	40% groundwater inflows are from other entities. Conscious mining policy for this WMA.
Queensland
Burnett	Negligible	Low	Medium	94% of water used was sourced from surface waters
Pioneer	Negligible	Low	Low	21% surface water returns from the economy (inflows) are from outside the entity.
Condamine-Balonne	n/a	Low	Low	Only 2% of surface water runoff was discharged to the lower reaches of the Murray-Darling Basin.
Barron	Negligible	Low	Low	About 90% of water used was sourced from surface water
Georgina-Diamantina	Low	Low	Low	As no flooding, all water used was sourced from groundwater
South Australia
Rocky River	High	n/a	Low	Recharge is equal to discharge, surface water runoff and baseflow were equal to surface water outflow
Barossa	High	Moderate	Low	Captured rainfall, extractions and diversions and outflow estimates dominated the balance representing more than 85% of the overall water resource
Patawalonga	High	Over-developed	Low	Groundwater discharge was significantly higher than recharge due to groundwater mining of the tertiary aquifer
Lower Limestone Coast	High	High	Low	Irrigation was a significant water use in the area with over 1,000,000 ML of groundwater used (~97% of inflows)
Tasmania
Macquarie	Negligible	Moderate	Low	25% of surface water returns are from irrigation.
South Esk	Negligible	Low	Low	Extractions and diversions were approximately 14% of the captured rainfall
Mersey	Negligible	High	Low	The water balance was dominated by rainfall, surface water flow out and water transfer out
Pittwater-Coal	Negligible	Low	Low	Extractions and diversions totalled 23% of captured rainfall
Victoria
Goulburn River	n/a	Moderate	Low	Environments’ share of surface water inflows was 19%
Broken River	n/a	Low	Low	Approximately 95% of extractions were from self-extracted water generally not metered
Ovens River	n/a	Low	Low	Runoff and outflow estimates dominated, representing more than 50% of the overall balance
Wimmera River	n/a	Low	Low	Environments’ share of total flow was 10%
Glenelg River	n/a	Moderate	Low	Large transfer out to Wimmera catchment for irrigation.
Moorabool River	n/a	Moderate	Low	Data accuracy for groundwater usage was low as much of it was self extracted and un-metered
Western Australia
Harvey River	n/a	Low	Low	Water use was predominantly from surface water resources (78%)
Collie River	Negligible	Low	Low	Water use was predominantly from surface water resources (74%)
Carnarvon GWA	High	Low	Low	Higher than average rainfall for 2004-05, 99% of surface water inflows are from other entities (Gascoyne River) due to the area definition.
Gnangara Mound	Moderate	Moderate	Low	Considerable portion of the Perth integrated water supply scheme which is highly developed and has had declining groundwater levels for many years.
South West Yarragadee	Moderate	Low	Low	Approximately a third of groundwater recharge discharges to ET. a further 20% is discharged to surface water as baseflow
Capital Cities
Australian Capital Territory water supply area	Moderate	Low	Low	Nearly wholly sourced from surface water, and groundwater is not well understood. 21% of inflows are sourced from other entities (NSW)
Adelaide water supply area	Moderate	Over-developed	Medium	37% urban treated effluent is returned to the economy
Brisbane water supply area	n/a	Low	Low	Desalination plant being considered along with water recycling.
Darwin water supply area	Low	Low	Low	The environments’ share of the total flow was 84%.
Hobart water supply area	n/a	Low	Low	96% of inflows are from other entities due to the boundary/catchment definition
Melbourne water supply area	n/a	Moderate	Low	Significant transfers in.
Sydney water supply area	High	Moderate	Low	6% surface water transferred in. Desalinisation plant is currently being considered.
Perth water supply area	Low	Low	Medium	Desalination plant commissioned in 2006.
Interjurisdictional Areas
Murray-Darling Basin	Negligible	Moderate	Low	Significant inflows from other entities.
Snowy River	Moderate	High	Low	Significant “in-stream” use as part of the hydro-electric scheme.
Cooper Creek	Low	Low	Low	High groundwater use possibly not licensed.
Ord River	Negligible	Low	Low	Limited development of the Order River Irrigation Scheme. Rising groundwater levels due to inefficient irrigation practices.
Lake Eyre Basin	Low	Low	Low	Significant groundwater inflows are from other entities, and significant groundwater extractions.
Great Artesian Basin	n/a	Over-developed	Low	Significant groundwater inflows are from other entities. Unacknowledged mining of the resource occurring.
Border Rivers	Negligible	Low	Low	34% of surface water runoff flows to downstream catchments

Definition of categories used in table:

Level of groundwater / surface water interaction (absolute):

Not applicable = no information available
Negligible = 0 < 5%
Low = 5 < 10%
Moderate= 10 < 20 %
High = > 20%

Water utilisation factor: Level of development of the water resource = extraction + diversions + transfers out / recharge + runoff + transfers in.

Not applicable = no information available
Low = 0 < 30%
Moderate= 30 < 70 %
High = 70 - 100%
Over-developed > 100%

Data reliability and availability factor (an average of the data reliability % from the Category A to E assessments for each component of the water balance and the data availability % for the water balance)

Not applicable = no information available
High = 0 - 25%
Medium= 25 - 50 %
Low = 50 - 100%
Poor > 100%

Responses to key questions relating to water cycle outcomes

Where do the majority of waters come from?

The water balances in south-eastern Australia and along the eastern coastline show that water is predominantly sourced from surface waters. In the northern and central regions groundwater is the dominant water source. In Western Australia groundwater is a major source of water for Perth and central coast region, surface water is dominant in south west and northern regions (e.g. Ord River).

What was the overall change in resource availability in 2004-05?

Eighteen of the 51 water balances showed a decrease in volume of surface water stored in 2004-05. Another 13 showed an increase in surface storage volume. Only two of these areas showed a marked increase; in the Goulburn (200 GL) and Murray-Darling Basin (830 GL), with most of the others showing an increase of between 1 and 20 GL.

Conversely, the areas showing a decrease in storage showed a more marked drop in water stored averaging between 50 and 200 GL. Some notable reductions in storage occurred in Brisbane (343 GL), Sydney (239 GL), Burnett (189 GL), Darwin (54 GL), Mersey (130 GL), Snowy (73 GL), and Ord River (1210 GL) water balances. Melbourne, Adelaide, Perth and Hobart had changes in storage less than 20 GL which is probably due to the fact that these cities rely heavily on transfers in for their water supply and the storages within the water balance area are balanced throughout the year.

Storage volumes in Melbourne’s Silvan Reservoir are maintained by transfers from the Upper Yarra Reservoir, which in turn receives inter basin transfers from the Thomson Reservoir.
Image by Robert Molloy, sourced from SKM

What was the contextual climatic story that influenced availability?

On average, 92% of average rainfall fell in 2004-05 for the water balance areas. In Victoria average rainfall occurred across the selected areas, with higher than average rainfalls falling in northern NSW in the Gwydir, Hunter and Namoi areas. In all other water balance areas rainfall ranged from 45% of average to 100% of average rainfall.

How sensitive were water restrictions to small changes in demand / climate / land use? (if known).

Water restriction information was collated for each of the water balance areas for the 2004-05. In many cases this information was a broad overview of the water restrictions which changed several times throughout the year. The impact of the water restrictions on demand and water extraction / use was not investigated as part of this project and requires a more in-depth review over a longer time period to determine the actual impact of water restrictions on water use. Generally it is known that in times of restrictions alternate water supplies (e.g. groundwater, effluent recycling, etc) are sought when surface water restrictions are applied. This has been noted in the Murray-Darling Basin over the last 10 to 20 years where the cap has restricted surface water use and alternative sources that were not capped such as groundwater have now been extensively developed.

What information is available about minor storages (farm dams) and how much influence do they have on water availability?

Some information was available on farm dams where specific studies have been undertaken, notably in south eastern Australia and south west Western Australia where the use of remote sensing has allowed for mapping of farm dams. In general the information is limited and in many of the water balance areas there was little data available. Even when information is available on the number of farm dams the actual capacity of the dams and volume used in any one year, or volume in storage at a particular date is not always known. Further work is required to understand the impact of farm dams on stream flows with some works already estimating significant impacts on streams in the Murray-Darling Basin and other regions.

What can be inferred from the relative levels of winter inflow and diversions with respect to sustainability of these practices?

Due to this assessment being undertaken on an annual basis the impact of winter inflows and other seasonal influences was not assessed. Climatic data has been presented on a monthly basis in the Regional Water Resources Assessments to add further contextual information for each area.

Can an estimate of the relative importance of groundwater /surface water interconnection be made from the balances?

An assessment of the importance of groundwater and surface water interactions has been made. This has highlighted that the interactions are significant in those areas where it has been assessed, and in many areas it is not well understood. Technical reviews of the methods to assess the groundwater and surface water interactions are currently occurring in many states and territories and the level of information and understanding of this issue is expected to increase in the next 5 to 10 years.

What usage data was obtained from the states/ territories and how did it compare to the ABS data or other sources of information?

Extraction and diversion volumes were obtained from the states and territories for each of the water balance areas. This data was compared with the level of entitlements and water use data compiled by the ABS and was found to differ significantly in many areas. The main discrepancies appear to arise from either groundwater or surface water private diversions and extractions not being included in the ABS numbers (e.g. not licensed).

Further discussion of the water balance results is provided in the Water Availability National Perspective report, and the Regional Water Balances report, which are both available on the Publications page.

For individual results of water balance assessments go to Regional Water Resources Assessments

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Last Updated 22/06/2007