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In this section you will find detailed information, including national overviews and state and regional level assessments, from the 2000-2002 National Land and Water Resources Audit theme assessments.
Water resources - Availability - Victoria
Victoria
Victoria Overview
Water is fundamental to Victoria's future. It is critical to Victoria's economic performance, and it is vital to the health of every community, not only because of the economic activity it generates, but also because of its environmental, aesthetic and recreational values. It is a necessary input to Victoria's primary industries, and underpins economic growth in rural and regional Victoria. After manufacturing, agribusiness is Victoria's largest export earner. Dairying is the most prominent agricultural activity in the State, with mixed farming, orchards, vegetables and grapes being the other main irrigated farming activities. Currently around 30% ($1.8 billion) of Victoria's gross value of production ($6.1 billion) is produced in the northern irrigation regions, and there are plans to increase farm income from irrigated agriculture by $650 million per annum by the year 2010.
At the same time, the limits to the water that can be sustainably harvested have been reached already in many river systems, and will be very soon in many others. Current average annual water use in Victoria is around 5788 GL/a, with 89% of needs being met by surface water resources (5166 GL/a) and 11% by groundwater (622 GL/a). A further 814 GL of surface water is used to meet commitments to New South Wales on the Murray system, bringing total surface water diversions to 5980 GL/a. This level of usage represents around 87% of the estimated sustainable yield for surface water, 85% for groundwater within designated Groundwater Management Units and only 25% of the total groundwater resource in Victoria (< 5000 mg/L TDS). By 2050 it is expected that use of surface water will have risen by 7% relative to current levels to around 6422 GL/a, and groundwater use is expected to rise by 29% to 804 GL/a. This level of use (at 2050) represents around 94% of the sustainable yield for surface water. Additional demands for surface water will be met through water trading and through efficiency gains in water supply delivery and use.
Detailed information about the history of development and the management of water resources over the past 150 years in Victoria can be found in DWR (1989, 1992), DCE (1991), and Powell (1989, 1998). The most significant period of development of resources for both rural and urban water use was during the three decades from 1960, with around 6,900 GL of storage capacity being added during this period. This represents almost half of the current storage capacity (of around 15,500 GL) throughout the State, and about 80% of this storage capacity was built for irrigation purposes.
By the 1980s, the development of surface water resources throughout the State could be described as being in a 'mature' phase. Infrastructure development over the past 150 years had harnessed around half of the State's ultimately available water resources, and relatively sophisticated supply systems had been developed in many instances, with interconnected storages existing within many basins and connections also existing between some basins. In the same decade, there was a growing acceptance that the rate of development of the resource that had occurred over the past two to three decades was not sustainable. It was estimated that if development were to continue at the same rate, all available resources would be developed within 35 years. In addition, it was recognised that the focus on development of the resource had resulted in many of rivers and streams being degraded by altered flow regimes. Conflict over water, particularly during sustained droughts, was also seen to be a significant emerging issue. It was therefore clear that there was a need for more efficient use and management of existing resources.
Accordingly, a wide-ranging program of institutional and legislative reform was implemented in the late 1980s to ensure that water is managed effectively and used efficiently and that appropriate protection is given to environmental values. As a result of this change in focus from the continued development of new resources to the efficient management and use of existing resources, there has been no major storage development since the completion of Thomson and Blue Rock dams in the 1980s. The program of reform initiated in the late 1980s has continued in the context of the national water reform agenda adopted by the Council of Australian Governments in 1994, which was subsequently included in the National Competition Principles Agreement in 1995. Victoria is now well placed to meet national requirements.
Groundwater is the minor partner in the supply of the State's water, being mainly used by rural towns to supplement their surface water supply sources (especially in times of drought) and for irrigation. It also provides the sole source of water supplies for many remote farms. With increased pressure on surface water resources, groundwater has seen increasing use, requiring more intensive management, which again is consistent with the national water reform agenda.
The programs and policies that have been implemented as part of the water reform agenda are providing a sound foundation for the sustainable and efficient management and use of resources. Over the last decade Victoria's water management framework has led to a significant movement of water into higher-valued uses, and to major advances in the way droughts are handled. Moreover, it has introduced strong incentives for efficiencies in water distribution and use, which are driving major upgrading of on-farm and water authority practices. The environment is now recognised as having a valid right to water. In some over-allocated systems like the Wimmera, water that has been saved through more efficient delivery systems has already been returned to the environment, and further action along these lines is being actively pursued.
There is nevertheless still a considerable task ahead, and a range of difficult issues to be worked through. This will necessarily involve extensive consultation with all stakeholders, as informed public debate (in particular in relation to setting the boundaries between water for agriculture and for the environment) is critical for gaining acceptance of a way forward. The challenge now is to manage a finite and scarce resource in an environmentally responsible and equitable way. This will involve pursuing further opportunities for water savings and reuse, facilitating the transparent re-allocation of water to more productive use through water markets, ensuring the efficient delivery of services, and restoring the health of rivers and catchments.
Surface Water Reporting Units
For this Audit, the basins as designated by the Australian Water Resources Council (AWRC) have been adopted in Victoria as the basic reporting unit. There are 30 AWRC basins in Victoria, of which 11 are located north of the divide and form part of the Murray Darling Basin. Two of the AWRC basins (the Thomson and Upper Murray) have been further subdivided for reporting purposes, to distinguish between the relatively developed and undeveloped river systems within the basins. All reporting units are referred to as Surface Water Management Areas (SWMAs). A total of 32 have been defined for Victoria.
Groundwater Reporting Units
Groundwater abstraction, allocation and use information has been reported at three levels - Groundwater Management Units (GMUs), Unincorporated Areas (UAs) and Province. For the purposes of the Audit GMUs have been assumed to be identical to the Groundwater Management Areas (GMAs) identified throughout the State, which are areas where groundwater development has already occurred or where there is potential for groundwater development. To date 63 GMUs have been identified which cover 90% of the total groundwater allocations in the State. Groundwater Provinces are based on a combination of the principle hydrogeological basins and geological zones within Victoria. The Unincorporated Areas comprise the areas between the GMUs and the Province boundaries. Sixty-three GMUs have been reported on, along with 18 UAs.
For further information contact the Victorian Department of Sustainability and Environment www.dse.vic.gov.au.
How much surface water does Victoria have?
Hydrology
The Great Dividing Range is the dominant physiographic feature of Victoria and is the dominant influence on the distribution of precipitation and, in turn, streamflow across the State. The higher average altitude of the Divide in the east causes the major proportion of the State's precipitation to occur in the eastern half of the State, generating approximately 80% of the total streamflow. North of the Dividing Range precipitation decreases rapidly with increasing distance from the Divide. To the south of the Divide precipitation is higher and more reliable due to the proximity of the highland areas to the coast.
Annual rainfall varies from over 1400 mm in the Victorian Alps and the Otway Ranges to around 250 mm in parts of the Mallee. The Victorian Alps are located in the Great Dividing Range in the south-east of the State and span the Kiewa, Ovens and Upper Murray River basins. The combined streamflow from these basins represents approximately 25% of the total streamflow generated across the State.
The mean annual streamflow of the State under undeveloped conditions is estimated as 20,188,300 ML, which is equivalent to approximately 5% of all flows in Australian streams.
River flows in Victoria show distinct variations in time, with streamflows showing both a seasonal pattern and substantial year-on-year variability in discharge. Across the State as a whole about 60% of average annual discharge occurs in the four month period from July to October. In the western streams this proportion approaches 75%. In all areas of the State, river flows decrease during the summer and autumn months. In general, those basins that have their headwaters in the upland areas of eastern Victoria have more reliable flows, while those in the west experience a greater degree of variability.
Victorian streams, like all Australian streams, generally exhibit a higher degree of variation in annual flows than streams in Northern America and Europe although the variations in Victorian streams are somewhat less than in most other Australian States.
Available Resource
The total annual 'divertible' surface water resource is the average annual volume of surface water that can be diverted utilising both existing infrastructure and potential infrastructure under the ultimate level of development. The divertible yield is estimated without consideration being given to in-stream environmental water requirements.
For Victoria, the total annual 'divertible' surface water resource of 10,220 GL represents approximately 51% of the total streamflow of 20,188 GL. The remaining 49%, or 'non-divertible' portion of the total surface water resource, refers to water that is unsuitable for development for a variety of reasons including poor quality, high cost, the need to protect environmental values (other than in-stream values), and other social factors (such as the need to protect sites of special cultural significance).
The 'sustainable' yield is the estimated maximum volume of water that can be diverted after taking account of in-stream environmental water requirements. It is calculated as a long term average annual volume. While this concept is apparently relatively straightforward as defined, in practice the sustainable yield is very difficult to determine. Once environmental flow requirements at particular points within a SWMA have been determined, using simulation models it is possible to derive an estimate of the average volumetric 'environmental allocation' and the 'sustainable yield' for the SWMA. While Victoria has a variety of programs underway aimed at identifying, improving and protecting environmental flow requirements, the necessary investigations take considerable time and resources and have not been completed for most catchments.
Given the short time frame of the Audit, it was necessary to make some broad assumptions, and use a variety of approaches, to derive estimates of the sustainable yield for SWMAs in Victoria. Consideration was given to environmental water requirements (known and likely), existing users' rights, and related social and economic impacts.
In summary:
- within the Murray Darling Basin, sustainable yields were equated to the average annual diversions from each SWMA with the Murray Darling Basin Cap in place. (The Cap limits annual diversions within the Basin to the 1993/94 level of development);
- for SWMAs in the southern part of Victoria where environmental values could potentially be threatened by further allocations, the sustainable yield was limited to the current allocation volume, pending the outcomes of further detailed investigations of environmental water requirements;
- for the remaining southern SWMAs, the sustainable yield was determined by calculating the total volume of water that can be extracted from the river system (during May to November) such that the degree of change to the natural flow regime is not 'unacceptable' as defined by the achievement of a rating of 5 for the Hydrology sub-index of the Index of Stream Condition. (Further information regarding the Index of Stream Condition can be found in the State Technical Report). Where the yield estimated using this method exceeded the assessed divertible yield of the SWMA, the sustainable yield was limited to the divertible yield.
Further details of the assumptions and methods adopted to determine sustainable yields, and the limitations of these methods, can be found in the State Overview and State Technical Reports.
For Victoria, the total sustainable yield is estimated to be 6,862 GL, or 34% of the total streamflow. Of this sustainable yield, 92% (equivalent to 31% of streamflow) has already been developed for use.
The management area with the most highly developed surface water resource is the Goulburn Basin, with a developed yield of 1,943 GL. This represents 31% of the total developed yield in the State.
| Basin/Surface Water Management Area | Mean Annual Run-off (GL/yr) | % of state | Natural mean annual out-flow (GL/yr) | In-flow (GL/yr) |
|---|---|---|---|---|
| Avoca River | 137 | .67 | no data | 0 |
| Avon River | 239 | 1.18 | 230 | 0 |
| Barwon River | 251 | 1.24 | 225 | 0 |
| Broken River | 326 | 1.61 | 238 | 0 |
| Bunyip River | 354 | 1.75 | 343 | 0 |
| Campaspe River | 305 | 1.51 | 163 | 0 |
| East Gippsland (Vic) | 655 | 3.24 | 887 | 232 |
| Glenelg River (Vic) | 705 | 3.49 | 633 | 0 |
| Goulburn River | 3,366 | 16.67 | 1,250 | 0 |
| Hopkins River | 406 | 2.01 | 399 | 0 |
| Kiewa River | 679 | 3.36 | 670 | 0 |
| Lake Corangamite | 121 | .6 | 0 | 0 |
| Latrobe River | 887 | 4.39 | 727 | 0 |
| Loddon River | 415 | 2.06 | 279 | 0 |
| Mallee (Vic) | 0 | 0 | 0 | 0 |
| Maribyrnong River | 126 | .62 | 118 | 0 |
| Mid-Murray River (Hume to SA Border) (Vic) | 0 | 0 | 3,874 | 6,338 |
| Millicent Coast (Vic) | 4 | .02 | no data | 0 |
| Mitchell River (Vic) | 1,100 | 5.45 | 1,088 | 0 |
| Mitta Mitta River | 1,439 | 7.13 | 1,419 | 0 |
| Moorabool River | 92 | .45 | 75 | 0 |
| Otway Coast | 750 | 3.72 | 728 | 0 |
| Ovens River | 1,692 | 8.38 | 1,666 | 0 |
| Portland Coast | 231 | 1.14 | 231 | 0 |
| Snowy River (Vic) | 863 | 4.27 | 1,667 | 804 |
| South Gippsland | 851 | 4.22 | 839 | 0 |
| Tambo River | 329 | 1.63 | 326 | 0 |
| Thomson-Macalister Rivers | 842 | 4.17 | 500 | 0 |
| Upper Murray River (Vic) | 1,364 | 6.76 | 2,183 | 822 |
| Werribee River | 147 | .73 | 105 | 0 |
| Wimmera - Avon Rivers | 317 | 1.57 | 0 | 0 |
| Yarra River | 1,200 | 5.94 | 779 | 0 |
How saline are Victoria's surface water resources?
Table: Surface water resource by salinity class for divertible yield (GL)
| Surface Water Managemnet Area | <500 mg/l (GL/yr) | 500 - 1500 mg/l (GL/yr) | 1500 - 5000 mg/l (GL/yr) | 5000 -14000 mg/l (GL/yr) | >14000 mg/l (GL/yr) | Total volume (GL/yr) |
|---|---|---|---|---|---|---|
| Victoria | 10,051 | 10 | 140 | 1 | no data | 10,200 |
| Avoca River | 4 | no data | no data | no data | no data | 4 |
| Avon River | 61 | no data | no data | no data | no data | 61 |
| Barwon River | 43 | no data | 49 | no data | no data | 91 |
| Broken River | 131 | no data | no data | no data | no data | 131 |
| Bunyip River | 99 | no data | no data | no data | no data | 99 |
| Campaspe River | 121 | no data | no data | no data | no data | 121 |
| East Gippsland (Vic) | 143 | no data | no data | no data | no data | 143 |
| Glenelg River (Vic) | 85 | no data | no data | no data | no data | 85 |
| Goulburn River | 2,477 | no data | no data | no data | no data | 2,477 |
| Hopkins River | no data | 6 | 5 | no data | no data | 11 |
| Kiewa River | 190 | no data | no data | no data | no data | 190 |
| Lake Corangamite | no data | no data | 1 | no data | no data | 1 |
| Latrobe River | 487 | no data | no data | no data | no data | 487 |
| Loddon River | 109 | no data | no data | no data | no data | 109 |
| Mallee (Vic) | no data | no data | no data | no data | no data | 0 |
| Maribyrnong River | 36 | no data | 18 | no data | no data | 53 |
| Mid-Murray River (Hume to SA Border) (Vic) | 1,639 | no data | no data | no data | no data | 1,639 |
| Millicent Coast (Vic) | 1 | 1 | 1 | 1 | no data | 1 |
| Mitchell River (Vic) | 435 | no data | no data | no data | no data | 435 |
| Mitta Mitta River | 941 | no data | no data | no data | no data | 941 |
| Moorabool River | 66 | no data | 8 | no data | no data | 73 |
| Otway Coast | 174 | no data | 31 | no data | no data | 205 |
| Ovens River | 664 | no data | no data | no data | no data | 664 |
| Portland Coast | no data | 4 | 8 | no data | no data | 12 |
| Snowy River (Vic) | 482 | no data | no data | no data | no data | 482 |
| South Gippsland | 133 | no data | no data | no data | no data | 133 |
| Tambo River | 278 | no data | no data | no data | no data | 278 |
| Thomson-Macalister Rivers | 683 | no data | no data | no data | no data | 683 |
| Upper Murray River (Vic) | 4 | no data | no data | no data | no data | 4 |
| Werribee River | 36 | no data | no data | no data | no data | 36 |
| Wimmera - Avon Rivers | 71 | no data | 24 | no data | no data | 95 |
| Yarra River | 467 | no data | no data | no data | no data | 467 |
How much of Victoria's surface water resource has been developed?
There are ten major water supply systems supplying the majority of users across the State. These are the Melbourne (and Mornington Peninsula and District), Otway, Ballarat, Coliban/Campaspe, Werribee, Geelong and Bellarine Peninsula, Latrobe Valley, Thomson/Macalister, Wimmera-Mallee, and Goulburn-Murray Irrigation District (GMID) supply systems. The GMID and the Melbourne metropolitan system are the largest of these. They are both integrated systems comprising transfer works that divert water across basin boundaries.
Some of the 345 towns scattered throughout regional Victoria (with a total population of around 1 million) are serviced via these larger systems, but there are also many smaller urban supply systems servicing local centres. There is a total of some 304 urban water supply systems throughout the State, 87% of which draw their supplies from surface waters.
There are about 80 storages (with a capacity exceeding 1000 ML) located across the State. These represent a total storage capacity of around 15,500 GL for Victoria.
How committed are Victoria's surface water resources?
Twenty-four SWMAs (75%) are categorised as highly developed in terms of allocation and 18 SWMAs (56%) are categorised as highly developed in terms of current diversion. Of the 24 SWMAs that are highly developed in terms of allocation, 21 are considered to be fully developed (i.e. category 3*). These fully developed SWMAs include:
- the five SWMAs that feed into the Gippsland Lakes (Tambo, Mitchell, Avon, Thomson-Macalister and Latrobe Rivers), for which the SYs have been set at the current allocations pending completion of the Gippsland Lakes environmental study;
- the Snowy River (Vic) SWMA for which the SY has been set at the current allocation pending the outcome of the Snowy Water Inquiry;
- two SWMAs (Yarra and Moorabool Rivers), for which the SYs have been set at the current allocations pending the outcome of the Streamflow Management Plans currently being developed;
- two SWMAs (Lake Corangamite and Hopkins River) where any further development is constrained by the high salinity of the resource;
- eleven SWMAs in the Murray Darling Basin where SYs have been set to average annual usage under the MDBC Cap.
For these fully developed SWMAs, further development can only take place if rights are acquired via water trading or via efficiency gains or, in the case of those SWMAs where studies are currently underway, where those studies identify the fact that further resources can be made available for allocation without detriment to environmental values.
The remaining three basins that are categorised as highly developed in terms of allocation (Werribee and Glenelg Rivers, and Millicent Coast) are considered to have some limited scope for further development. There is further scope available in the seven SWMAs that fall into the medium (Bunyip, Maribyrnong and Barwon Rivers) and low (East Gippsland, South Gippsland, Otway Coast and Portland Coast) levels of resource development in terms of allocations.
Note: In the table below the total water diverted from the Mitta Mitta River SWMA includes 814 GL/yr diverted to NSW
| Basin/SWMA | Volume diverted (GL/yr) | Sustainable (GL/yr) | Diversion Development class |
|---|---|---|---|
| Avoca River | 4 | 4 | FULL DEVELOPMENT |
| Avon River | 8 | 8 | FULL DEVELOPMENT |
| Barwon River | 41 | 71 | MEDIUM DEVELOPMENT |
| Broken River | 32 | 32 | FULL DEVELOPMENT |
| Bunyip River | 11 | 99 | LOW DEVELOPMENT |
| Campaspe River | 121 | 121 | FULL DEVELOPMENT |
| East Gippsland (Vic) | 1 | 143 | LOW DEVELOPMENT |
| Glenelg River (Vic) | 72 | 85 | HIGH DEVELOPMENT |
| Goulburn River | 1,943 | 1,943 | FULL DEVELOPMENT |
| Hopkins River | 7 | 11 | MEDIUM DEVELOPMENT |
| Kiewa River | 9 | 9 | FULL DEVELOPMENT |
| Lake Corangamite | 1 | 1 | FULL DEVELOPMENT |
| Latrobe River | 161 | 262 | MEDIUM DEVELOPMENT |
| Loddon River | 109 | 109 | FULL DEVELOPMENT |
| Mallee (Vic) | 0 | 0 | FULL DEVELOPMENT |
| Maribyrnong River | 8 | 33 | LOW DEVELOPMENT |
| Mid-Murray River (Hume to SA Border) (Vic) | 1,639 | 1,639 | FULL DEVELOPMENT |
| Millicent Coast (Vic) | 1 | 1 | FULL DEVELOPMENT |
| Mitchell River (Vic) | 12 | 19 | MEDIUM DEVELOPMENT |
| Mitta Mitta River | 835 | 835 | FULL DEVELOPMENT |
| Moorabool River | 17 | 46 | MEDIUM DEVELOPMENT |
| Otway Coast | 20 | 205 | LOW DEVELOPMENT |
| Ovens River | 26 | 26 | FULL DEVELOPMENT |
| Portland Coast | 2 | 12 | LOW DEVELOPMENT |
| Snowy River (Vic) | 3 | 6 | MEDIUM DEVELOPMENT |
| South Gippsland | 12 | 136 | LOW DEVELOPMENT |
| Tambo River | 3 | 7 | MEDIUM DEVELOPMENT |
| Thomson-Macalister Rivers | 342 | 428 | HIGH DEVELOPMENT |
| Upper Murray River (Vic) | 4 | 4 | FULL DEVELOPMENT |
| Werribee River | 33 | 36 | HIGH DEVELOPMENT |
| Wimmera - Avon Rivers | 95 | 77 | OVER DEVELOPMENT |
| Yarra River | 421 | 467 | HIGH DEVELOPMENT |
The volume diverted is the total volume of the SWMA's surface water resources diverted for use both within the management area and for export to other management areas.
A four-class classification system was developed to provide a simple method to communicate the status of the use and allocation of Australia's water resources in relation to sustainable water management.
It is important to recognise that adequately quantifying a sustainable flow regime or sustainable yield and consequent operating rules is a complex matter. State, Territory and scientific agencies continue to develop and apply methods and measures for determining sustainable flow regimes and sustainable yields.
This categorisation provides a general guide only. Please refer to the State and Territory Overview and Technical reports for detail on the analysis methods used.
| Category | Development status | ||
| 1 | <30% | Low development | |
| 2 | 30 - 70% | Moderate development | |
| 3 | 70 - 100% | Highly developed | |
| 4 | 100% | Overdeveloped |
* Water use as a percentage of sustainable flow regime (surface water) and sustainable yield (groundwater)
How much groundwater does Victoria have?
Hydrogeology
The principal groundwater resources in Victoria are contained in Tertiary or younger aged unconsolidated sediments. By volume, the most significant resources are generally located to the south of the Great Dividing Range, with additional significant resources in the arid west and north west. Bore yields vary from as little as 0.5 L/s through to high capacity bores producing in excess of 100 L/s.
Available Resource
It is currently estimated that the groundwater resource in Victoria is capable of providing 3660 GL/a on a sustainable basis. This resource is variable in quality, and is hence applicable to differing use types according to the salinity of the waters. The resource is capable of providing 308 GL for potable use (<1000 mg/L) (all located in GMUs), 1900 GL for agricultural use (1000 - 1500 mg/L) (450 GL of which is in GMUs) and an additional 1450 GL (>5000 mg/L) (36 GL of which is in GMUs) for industrial use. The greatest potential for use occurs in the West Gippsland and Otway regions of the State. The most intensive use of groundwater occurs in the Shepparton and East Gippsland areas.
The depth to the resource varies from as little as 5 metres through to greater than 1000m. Resources less than 100m in depth are generally well developed. Deeper resources are developed primarily where high yields can be obtained and/or where artesian pressure enables free flow.
Sustainable Yield and Environmental Allocation
Sustainable yields have been estimated for all GMUs in Victoria. While a nationally agreed definition of sustainable yield is now available, there is as yet no agreed methodology for determining sustainable yields. In Victoria, the sustainable yield methodology varies across the State according to the aquifer characteristics being investigated.
In most cases, because of the lack of usage data and, in many cases bore hydrograph data, the sustainable yield has been determined as a percentage of rainfall, with adjustments made to take account of environmental requirements to the extent possible given currently available information. Checks on aquifer storage, river recharge/ discharge, aquifer throughflow, well interference, seawater intrusion and pressure/head loss are incorporated into the methodology. The most commonly considered issues are baseflow to river systems and the intrusion of seawater. The requirements of groundwater dependent ecosystems (GDEs) have not generally been considered explicitly in this process, as their requirements are as yet poorly understood. However, in estimating sustainable yields for groundwater management units, efforts have been made to avoid significant interference with GDEs. As the requirements of groundwater dependent ecosystems are evaluated, current government policy will allow for variation of the sustainable yield if the prospect of a detrimental impact emerges (e.g. seawater intrusion, which may result in aquifer salinisation).
It should be noted that the derived estimates of sustainable yield are relatively subjective. Until there is more substantial data on usage it will not be possible to derive water balances for the GMUs, and determine the recharge that provides the basis for sustainable yield. Similarly, the lack of information about the requirements of groundwater dependent ecosystems has meant that some fairly broad assumptions about these requirements have had to be made. Because of these, and other uncertainties such as the impact of climate variability and the likely impacts of plantation forestry on sustainable yields, a conservative approach has been adopted in the estimation of sustainable yields for GMUs.
When resource commitments in a GMU reach 70% of the estimated sustainable yield, the area is declared a Groundwater Supply Protection Area (GSPA), groundwater community management groups are established and more intensive management is triggered. This includes the development of a Groundwater Management Plan for the GSPA, which involves (inter alia) the establishment of programs to meter usage and more detailed monitoring of groundwater levels to allow better determination of the sustainable yield. It has become evident that some GMUs have been over-allocated prior to their delineation as a GMU in 1996. Review of the sustainable yield in these systems and other highly developed resources is being given a high priority in the GSPA process to ensure that the systems do not become over used, or have adverse impacts on any GDEs.
In areas outside of the GMUs the sustainable yield estimates are of low reliability, especially in the fractured rock systems. In areas such as the volcanic rises, sustainable yield estimates can be misleading due to the high recharge rates and low aquifer yields and, hence, low extraction capabilities. Care must be taken when interpreting resource availability in fractured rock systems, as it will not necessarily be the same as the sustainable yield. The salinity of the resource should also be considered at all times when determining groundwater resource availability, particularly in areas outside of the GMUs where the resource can be highly saline (>14,000 mg/L) and of little beneficial use.
Further details on the methodology used to estimate sustainable yields, and the limitations of these methods, are provided in the State Technical Report.
How committed are Victoria's groundwater resources?
Table: Allocation volumes (GL/yr in each development category)
Note: "GMU"=Groundwater Management Unit "UA"=Unallocated Area
| Province | Over | High | Med | Low | Total (GL/yr) | |
|---|---|---|---|---|---|---|
| Gippsland | GMU | 161 | 10 | 15 | 1 | 187 |
| UA | no data | no data | no data | 19 | 19 | |
| Lachlan | GMU | 256 | 198 | 58 | 27 | 538 |
| UA | no data | no data | no data | 71 | 71 | |
| Murray | GMU | 1,125 | 417 | 50 | 15 | 1,607 |
| UA | no data | no data | no data | 27 | 27 | |
| Otway Highlands | GMU | no data | no data | no data | no data | no data |
| UA | no data | no data | no data | 1 | 1 | |
| Otways | GMU | 24 | 34 | 93 | 187 | 336 |
| UA | no data | no data | 1 | 32 | 33 | |
| Port Phillip | GMU | 5 | 1 | 12 | 1 | 18 |
| UA | no data | no data | no data | 9 | 9 | |
| Westernport | GMU | 4 | 8 | no data | 1 | 12 |
| UA | no data | no data | no data | 3 | 3 |
A four-class classification system was developed to provide a simple method to communicate the status of the use and allocation of Australia's water resources in relation to sustainable water management.
It is important to recognise that adequately quantifying a sustainable flow regime or sustainable yield and consequent operating rules is a complex matter. State, Territory and scientific agencies continue to develop and apply methods and measures for determining sustainable flow regimes and sustainable yields.
This categorisation provides a general guide only. Please refer to the State and Territory Overview and Technical reports for detail on the analysis methods used.
| Category | Development status | |||||
|---|---|---|---|---|---|---|
| 1 | <30% | Low development | ||||
| 2 | 30 - 70% | Moderate development | ||||
| 3 | 70 - 100% | Highly developed | ||||
| 4 | 100% | Overdeveloped |
| Province | <1500 mg/l (GL/yr) | 5000 mg/l (GL/yr) | 14000 mg/l (GL/yr) | >14000 mg/l (GL/yr) | Total volume (GL/yr) | |
|---|---|---|---|---|---|---|
| Victoria | GMU | 242095 | 61915 | 244357 | 149085 | 2852010 |
| UA | 360000 | 218240 | 3810515 | |||
| Gippsland | GMU | 36,550 | 10 | 125 | 4 | 32 |
| UA | no data | 360 | no data | no data | 62 | |
| Lachlan | GMU | 342,635 | 268 | 6 | 7 | no data |
| UA | no data | no data | no data | 429 | no data | |
| Murray | GMU | 157,010 | 458 | 251 | 128 | 30 |
| UA | no data | no data | no data | no data | 500 | |
| Otway Highlands | GMU | no data | no data | no data | no data | no data |
| UA | no data | no data | no data | 86 | no data | |
| Otways | GMU | 55,850 | 198 | 597 | 78 | no data |
| UA | no data | no data | no data | 133 | no data | |
| Port Phillip | GMU | no data | no data | 3 | 27 | 5 |
| UA | no data | no data | no data | no data | 49 | |
| Westernport | GMU | no data | no data | 8 | no data | 11 |
| UA | no data | no data | no data | no data | 20 |
How much water does Victoria trade?
The Total reported Volume Traded in Victoria is 119 GL; in 160 transactions.
The State and Territory water management agencies continue to consider water use efficiency and optimisation strategies within existing infrastructure (e.g. water supply efficiency, precision irrigation and scheduling, water recycling, trading and pricing) as part of water resource development planning.
Recognising that water is a finite resource, the States and Territories have developed water allocation systems where security and reliability are assigned to entitlement, trading is provided so water can be moved to high value uses and the choices of individuals are maximised.
Part of the decision-making framework to enable and facilitate water trading, changes in water allocation and definition of rights to water is the need for water use monitoring. Water use monitoring will assist decision-making and provide an opportunity over time to evaluate the effectiveness of allocation policies.
Environmental water requirements
Surface Water
The Victorian Government is committed to striking a balance between satisfying existing demands to urban centres and irrigation industries and improving the environmental flow regime of rivers. The provision of water allocations for the environment is being addressed via a number of programs, which are detailed below. The aim is to maintain and, where possible, restore the environmental values of rivers and wetlands, whilst recognising existing entitlements.
Bulk Entitlements
Under the legislative framework of the Water Act 1989, Victoria's bulk entitlement (BE) program ensures secure, well-defined property rights, separate from land title, and it also enables the provision of water for the environment, either by establishing BEs specifically for the environment or by imposing conditions which specify an environmental flow regime on entitlements held by water authorities.
The first phase in implementing BEs throughout Victoria, involves the conversion of existing rights to water to BEs. While this conversion process is focussed on the conversion of existing ill-defined rights to water, it also provides the opportunity for negotiation of enhanced environmental flows (e.g. through adjustments to system operating rules).
To date, flow-sharing arrangements have been negotiated and agreed with stakeholders for 65% of some 190 identified water supply systems. One hundred and twenty formal BEs have been granted, which account for around 75% of the total volume of water extracted throughout the State. These include BEs for the Goulburn and Murray regulated systems in northern Victoria, which together account for about two-thirds of Victoria's usage.
The BE conversion process has already lead to improvements in environmental flows for various rivers around the State including the Werribee and Maribyrnong Rivers in the south-west of Victoria, the Thompson and Latrobe Rivers in Gippsland and the Goulburn River north of the Divide. BEs for the River Murray include specific provisions for looking after wetlands along the Murray, and consideration of provisions for in-stream flows is continuing. Work is also continuing on other major river systems including the Ovens, Broken, Loddon, Barwon, and Yarra Rivers.
While the BE conversion process has led to improvements in environmental flows (in around 90% of the systems converted to date), it does not typically result in environmental flow provisions that fully meet the needs of the environment. Environmental requirements will receive a high priority in the granting of new BEs, although no new BEs have as yet been granted. Ecological sustainability must be assessed and taken into account before any revisions can be made to a BE, and environmental requirements must also be met before any new BEs are granted.
Streamflow Management Plans
Provisions for environmental water requirements are also being made in Streamflow Management Plans (SMPs) for unregulated rivers that are not covered by the BE process. SMPs differ from BEs in that they are plans for the management of a number of diversion licenses on unregulated rivers rather than an explicit property right. These SMPs establish environmental objectives, environmental flow provisions (immediate and, where necessary long term), rostering rules for diversions in times of reduced flows, trading rules, and rules governing the granting of new licenses. The plans include mechanisms for reallocating water where negotiated environmental flows fall short of environmental flow requirements.
Priority is being given to the development of SMPs for stream systems that are recognised as being stressed. To cover the entire State, it has been estimated that around 100 SMPs will be required. Thirty nine streams have been identified as priority streams requiring SMPs. A total of 20 SMPs are currently at various stages of preparation. The status of SMPs for the identified priority can be summarised as follows:
- Draft SMPs have been prepared for three streams - the Merri River, Gellibrand River and Upper Latrobe River.
- Background information has been collected for 14 streams.
- A project group has been established for 8 streams.
- SMPs for the remaining 14 streams are scheduled for commencement in the next two years.
Preparation of these SMPs is both time-consuming (taking about two years) and expensive (costing over $100,000 per plan). Consideration is being given to the possibility of undertaking rapid assessments and putting in place some interim diversion limits and rules, so that some development via the issuing of new licences can continue in less stressed valleys, with reasonable confidence that environmental damage will not result.
The aim is to have SMPs prepared for all priority streams by the year 2005. The SMPs will provide a framework of rules to meet agreed principles to ensure the long-term environmental sustainability of rivers and streams and, by clarifying rights to water, create certainty regarding water availability for existing and possible future agricultural or other development. Regular review of plans is proposed as a critical element of an adaptive strategy for streamflow management.
Stressed Rivers Program
While improvements to environmental flows are achieved in about 90% of cases in the conversion of BEs, these improvements are often at the margin - the emphasis is on preventing further decline and on clarifying and protecting the rights of existing users. In a number of streams, further action to restore flows is called for.
The Stressed Rivers Program involves the identification of rivers that are stressed due to inadequate flow regimes, and the development and implementation of comprehensive work plans (River Restoration Plans) to improve their condition. These Plans will build on existing environmental provisions. They will set clear objectives for the improvement of river health, set priorities and identify mechanisms for enhancing the environmental flow regime, identify complementary in-stream and riparian habitat works that will maximise environmental gains, and establish agreed cost sharing arrangements for implementation of the Plans.
Progress to date with this program is as follows:
- Establishment of a Scientific Reference Panel (in 1997) that developed and applied criteria to identify and prioritise flow-stressed rivers for action. The Panel identified 35 river reaches as suffering a degree of stress on the basis of changes to their flow regimes. Based on criteria such as the environmental significance of the river, and the realistic potential for restoration, the Panel then proposed eight reaches as the priorities for action.
- Allocation of $400,000 by the Victorian Government for the development of eight River Restoration Plans by Catchment Management Authorities.
- Development of broad approach to determine action.
- Completion of the first case study on the Snowy River.
- Commencement of two further case studies for the Avoca/Wimmera/Glenelg/Avon and Thomson Rivers with scheduled completion of the draft plan by late 2001.
- Development of guidelines (based on the case studies) for developing integrated River Restoration Plans.
The aim is to have River Restoration Plans completed for the eight priority rivers (Glenelg, Avoca, Broken, Maribyrnong, Loddon and Lerderderg Rivers, the Thomson River downstream of Cowwarr Weir, and Badger Ck) by the year 2002. The Snowy River is also recognised as a priority river but, because of its national significance, it is regarded as a special case (see Management Initiatives Section below).
Groundwater
The Water Act 1989 requires that the environmental water requirements be considered in determining the sustainable yields of groundwater systems. The methodology adopted to date in estimating the sustainable yield of Groundwater Management Areas involves checks on aquifer storage, river recharge/discharge, aquifer throughflow, well interference, seawater intrusions and pressure/head loss. However, as noted above, while efforts are made to ensure that sustainable yields are set to avoid significant interference with groundwater dependent ecosystems (GDEs), the methodology does not yet give explicit consideration to the water requirements of, and provisions for GDEs.
As yet, there is no accepted definition of GDEs and their water requirements and appropriate provisions for their protection are not well understood. Consequently, no method yet exists for assessing these requirements.
The most commonly known GDE is river baseflow, and the interaction between groundwater and surface water is only partly understood. The variability within streams and across catchments means that no one methodology can be used to determine baseflow in streams, nor to determine the ecological impacts of reducing baseflow as a result of reductions in groundwater levels. Provisions to allow for the water requirements of GDEs will most likely require conjunctive management of surface water and groundwater resources to ensure that use of groundwater does not impact on surface water resources, and vice versa. It has been mooted that this could be undertaken via the development of 'Water Management Plans', which would encompass both the surface water and groundwater resources within a catchment or region.
Currently there is a push through the National Groundwater Committee for development of a definition of GDEs and a consistent methodology for taking these requirements into account in allocating groundwater. As this information becomes available it will be incorporated into the assessment of the sustainable yields of groundwater systems.
Further information
- Victoria Water Resources Assessment 2000 Report
- Victoria Water Resources Assessment 2000 Technical Report
- report from the study of Streamflow data and modelled streamflow
- Link to data available for download on the:
- extension of unimpaired monthly streamflow data and regionalisation of parameter values to estimate streamflow in ungauged catchments (NLWRA 2000)
- Surface Water Management Areas
- Groundwater management units and provinces - ARC/INFO export
- Link to the Map Maker to make a map using this information.
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