Australian Natural Resources Atlas

Natural Resource Topics

Water - New South Wales - Water Resources Overview

Surface and Groundwater Management, Availability, Allocation and Efficiency of Use
State of New South Wales Water Resources Overview

Introduction

Water is one of our most precious natural resources and one that needs to be managed for the benefit of the whole NSW community. Water needs to be shared equitably between competing users such as towns, industry, and agriculture, while ensuring that the basic health of our aquatic ecosystems is maintained and not compromised.

Over the last few decades awareness has grown of the need to sustainably manage the whole water cycle and all of our water resources, including water in rivers, groundwater and other ecosystems such as wetlands and floodplains. Sustainable water management in NSW has therefore become a very complex issue and one that is constantly evolving.

NSW is in the midst of implementing a series of major water reform initiatives, which is changing many of the fundamental ways in which water is managed and shared between extractive users and the environment. A key element of the change is the NSW approach of providing an environmental flow share over the full range of flows in rivers. As a consequence of still being in the process of developing many of the initiatives, which is utilising a significant portion of government resources, some of the reporting requirements of the National Land and Water Resources Audit cannot be fully met at this stage. Where appropriate links have been provided from the Audit data to the appropriate NSW government Internet site. The NSW government sites are updated on a regular basis.

Legislative Framework

The water reform process began in the 1980s, with increasing recognition of environmental needs and changes to institutional and pricing arrangements. This was followed in 1995 and 1997 with a comprehensive set of water policy reform initiatives.

With finalisation of its policy position on a number of water sharing issues, through a discussion paper and consultation process, the Government released a white paper - 'A proposal for updated and consolidated water management legislation for New South Wales', in December 1999.

The proposed new legislation will include the following elements:

The proposed Water Management Act will replace a number of Acts that presently relate to water management in NSW. This will allow the Minister for Land and Water Conservation to have the role of the State's main water manager. Other reforms will be achieved by merging the operational parts of those Acts into the proposed Water Management Act. Redundant functions or duties will be repealed, and where possible, a single process for administering approvals, appeals and other similar arrangements will be incorporated in the new Act.

Certain operational provisions of the Water Act (1912) will be carried over with appropriate links to the proposed Water Management Act.

A number of other Acts have been created to cover the commercial operation of the major urban water authorities, Sydney Water Corporation (SWC), Hunter Water Corporation (HWC) and the privatised irrigation schemes.

COAG Compliance

NSW is progressing well with its implementation of the COAG Water Reform Framework. The water reforms have been advanced on a "whole of government" basis, with co-ordination provided by the Water Industry IDC and the Water Chief Executive Officers' (CEOs) forum. A significant feature of the NSW reforms has been the development of close government/community partnership mechanisms for water management planning and an emphasis on socio-economic assessment. Key elements of NSW actions are:

Cost Recovery and Pricing

Institutional Reform

Allocation and Trading

Environment and Water Quality

Public Consultation and Education

Water Industry Structure

The NSW water industry can be divided into two broad groups. The first group consists of organisations responsible for the management, regulation and auditing of the water industry. Included within this group are the DLWC, Environmental Protection Agency (EPA), HRC and IPART. The second group consists of operational organisations responsible for the supply and delivery of water to customers. Included within this group are the State Water Division of DLWC , the SWC and the HWC. Also within this group are a number of bodies licensed by the Water Act, who supply water to customers, including Irrigation Corporations, rural urban water supply schemes, Broken Hill and Cobar Water Boards and Gosford Wyong Water Supply Authority.

NSW has retained the operation of dams and the rivers in the regulated irrigation valleys within a government agency, as it considers operation of these systems, for river environmental needs, is at a development phase and it is too early to separate this role from the government. State Water operates as a business arm of DLWC; operating and maintaining supply infrastructure and supplying water to licensed users in those valleys. Licensed users in the Murray, Murrumbidgee and Lachlan valleys include the previous government Irrigation Areas and Districts that are now either private irrigation companies or state corporations. By the end of 2000, State Water will have full transparency in costing and full commercial accounting satisfying Treasury requirements for competitive neutrality.

The community and industry based WAC provides independent advice to the Minister for Land and Water Conservation on water resource management issues, and assists in major policy development and the review of water management plans, prior to their endorsement by Government. Fifteen water management committee's oversight the development of valley water sharing rules and ultimately water management plans. Five more management committees will begin to operate within year 2000.

Surface Water Resource

Reporting Units

For this Audit, the 55 surface water management areas, as designated by the DLWC, and as shown in Figure 1, have been adopted as the reporting unit for NSW. These surface water management areas largely coincide with the old Australian Water Resources Council (AWRC) basins. The only exceptions are the basins within which major storages are operated by the Department and the Barwon Darling management area.

In those basins with major storages the AWRC basin has been further subdivided to distinguish between those parts of the basins in which the DLWC regulates part of the river system to assure supply (regulated basin) and those where it does not (unregulated basin). In a number of the other basins, such as the Hawkesbury-Nepean, Sydney, Shoalhaven and the Snowy, significant regulation is carried out by other agencies but these basins have not been included in the DLWC regulated category. The regulated basins include the Murray-Riverina, Lower Darling, Murrumbidgee, Lachlan, Macquarie, Namoi, Gwydir and Border Rivers within the Murray -Darling basin, and the Bega, Hunter, and Richmond Rivers in coastal NSW. The subdivision boundaries are shown in Figure 1.

1. NSW Surface Water Management Areas

Map of NSW Surface Water Management Areas

Hydrology

By world standards Australia receives little rainfall on average, and loses much of this to evaporation. Australia not only has a low average rainfall compared with other continents, but its runoff averages only 12% of rainfall compared with around 40% for Europe and North America. For NSW the runoff averages 17% for the coastal basins (varying between 12% and 30%) and 3.5% for the inland basins (varying between 0.01% and 31%).

About 75% of the runoff occurs on the coast where 90% of the population is concentrated; yet the coast uses only about 20% of the total water used in the State. Eighty percent cent of water use occurs west of the Great Dividing Range, where only 25% of the surface runoff occurs.

The mean annual streamflow of the State under natural conditions is 42000 GL, which is equivalent to approximately 10 % of all flows in Australian streams.

NSW is located between the summer monsoon rainfall system of northern Australia and the winter cold front rainfall system of southern Australia. River flows in NSW show distinct variations in time, with streamflow showing both a seasonal pattern and substantial year to year variability in discharge.

The inland Murray and Murrumbidgee Rivers in the south of NSW experience most of their runoff in the late winter/spring period, with about 58% of the average annual natural flow in the Murrumbidgee River occurring in the four month period from July to October. The seasonal pattern in the northern inland rivers is less obvious with 36% of the average annual natural flow in the Gwydir River occurring in the four month period from July to October, and 31% in the three month period from January to March. The annual flow in the southern inland rivers is less variable than in the north rivers with the minimum and maximum annual natural flows for the Murrumbidgee being 12% and 392% of the average annual natural flow, while for the Gwydir River the range is 5% to 480%. The Macquarie River located in the central inland part of NSW demonstrates the most variability of the western flowing rivers with minimum and maximum annual natural flow ratios of 3% and 780%.

The inland rivers with the lowest average annual flows are those flowing from Queensland and crossing the border west of Mungindi. Therefore it is not unexpected that the Darling River is subject to extreme variability with minimum and maximum annual natural flow ratios of 7% and 300 %.

For coastal streams the catchment size and distance from the coast are the main factors influencing the flows. The large coastal catchments of the Clarence, Hunter and Hawkesbury -Nepean Rivers have proportionally low rates of flow. The exception is the Snowy River which benefits from snow melt, although a large part of its flow is now diverted inland.

Available Resource

The total average annual surface water resource for NSW is 42000 GL. This information has been determined from a combination of water resource system models and historical flow analysis.

The total annual divertible surface water resource for NSW cannot be provided at this stage as yield information cannot be determined for the unregulated rivers in the State. This is due to the lack of

NSW has therefore taken the approach that it is better to await the availability of data based on reliable and realistic analysis than to divert limited resources from the water reform process at this time.

NSW has, consequently, placed a high priority on the management of the unregulated rivers. Management plans for the most highly stressed unregulated rivers will be prepared by 2001. Plans for other stressed and high conservation unregulated rivers will be completed by 2003, and all major unregulated rivers completed by 2005.

As studies are completed yield information for unregulated streams will be available on the DLWC web site www.dlwc.nsw.gov.au

With respect to the regulated streams, most of these occur inland and are part of the Murray-Darling Basin. As this basin is subject to a cap on diversions, NSW has assumed that there will be no further infrastructure development in the basin that would increase diversions. In fact in the valleys where NSW has implemented environmental flow rules average annual diversions are expected to decrease below the MDBC cap values.

In these basins the divertible yield has been determined on the basis of simulation models which assume the 1993/94 levels of infrastructure development, cap management rules and, with the exception of the Macquarie basin, make no major provision for environmental flows. On the basis of no further development under the MDBC cap. the developed yield has been taken to be equal to the divertible yield for these basins. Finally, the sustainable yield has been taken as the average annual use with current infrastructure development and MDBC cap plus environmental flow rules.

For the regulated NSW portion of the Murray-Darling basin, both the total divertible and the developed yield is 68% of the total resource for that portion of the basin; while the sustainable yield is 42% of the total resource. This excludes those management areas where a sustainable yield is yet to be determined (the Murray, Barwon-Darling and NSW Border Rivers). Each of these three areas are considered to be over developed.

Of the coastal basins in which parts of the river systems are regulated by the DLWC, only the Hunter has been modelled and has yield values available; the remaining basins (Richmond and Bega), and those in which stream controls are exercised by other bodies, have not had yield values determined.

As a result of having more reliable streamflows in the southern valleys in the NSW portion of the Murray-Darling basin, the NSW management area with the most highly developed surface water resource is the Murrumbidgee basin, which has a developed yield of 2,186 GL. This represents 25% of the total resources and 36% of the divertible yield of the NSW portion of the Murray-Darling basin.

Developed Use and Allocation

The major use of water in NSW is for irrigation and most of the irrigation development is located inland in the Murray-Darling basin.

The total volume of surface water allocated for use in NSW cannot be provided. Volumetric allocations have only been attached to licensed entitlements on the regulated rivers and the Barwon-Darling. At this stage licenses on unregulated rivers do not have volumetric allocations and a volumetric allocation is yet to be developed for the SWC and the HWC. As discussed in the Water Resource Management and in the Technical Report, NSW is progressively converting unregulated river licenses to volumetric management. As studies are completed, volumetric allocation information for unregulated streams will be made available on the DLWC web site www.dlwc.nsw.gov.au.

For the NSW regulated rivers and the Barwon-Darling portion of the Murray-Darling basin the total volume of water allocated for use is 7,995 GL.

NSW does not comprehensively collect details of crop usage. The average Level One use has been provided for the inland regulated rivers, the Barwon-Darling and the Hunter Basin based on the average use over the last five years at current levels of development, and MDBC cap (where applicable) and environmental flow management rules, from simulation models. Level one use has also been provided for the 1996/97 year. Water use is dominated by irrigation, which accounts for 95% of the total water allocation and uses an estimated 6,010 GL in an average each year. The difference between allocation and average use is due, in the main, to the effects of climate on the availability of the resource, with management responses to ensure Cap compliance, and some under-utilisation of allocations, also contributing.

Urban and industrial use accounts for a further 4% of the total water allocation, which is estimated to result in 253 GL of total use. Rural supplies only account for around 1% of total allocations, and an estimated 63 GL of annual use on average.

Water Supply Systems

There are eight major regulated river systems servicing predominantly irrigation development. In these systems, the river channel itself is the major water supply system from the one or more headwater storages. These systems occur in the Murray, Murrumbidgee, Lachlan, Macquarie, Namoi, Gwydir and Border River catchments in the Murray-Darling basin, and the Hunter River catchment on the coast. The major urban water supply schemes operated by Sydney Water Corporation services the greater Sydney region, the Hunter Corporation services Newcastle and the Gosford-Wyong Joint Water Supply Authority services the central coast. They are integrated systems that comprise of a number of dams and transfer works that divert water across basin boundaries. A number of other smaller rural urban water supply schemes exist on the coast and the inland. Most of these do not involve diversion of water across basin boundaries.

There are 90 storages (each with a volume capacity exceeding 1000 ML) located across the State. These represent a total storage capacity of 32065 GL.

Categorisation

The percentage of management areas in each 'development' category is summarised in Table 1.

Summary of Surface Water Management Area (SWMA) 'Development' Categories

Category Number Category Description Number of SWMAs (%)
1 Low Level Resource Development 30
2 Medium Level Resource Development 21
3 High Level Resource Development 5
4 Over Developed Resource 44

The Category 4, over-developed management areas comprise an area of some: 409000 sq. km

The NSW Water reform initiatives adopted a catchment classification system based on assessed level of environmental degradation (environmental stress) and proportion of flow extracted (hydrologic stress). This approach results in a matrix of 9 classifications of stress, which are grouped in 3 categories.

Summary of Surface Water Management Area (SWMA) 'Stressed Rivers' Categories

Category Number Category Description Number of SWMAs (%)
1 Unresolved 10
2 Low Combined Stress 35
3 Medium Combined Stress 26
4 High Combined Stress 29

The categorisation in Table 2 is the aggregated category for each SWMA based on the area of the 'Stressed Rivers' assessment for each river within in each SWMA.

Groundwater Resource

Reporting Units

Groundwater information has been reported at three levels- Groundwater Management Units (GMUs), Unincorporated Areas (UAs) and Province. GMUs are those parts of NSW where groundwater usage is intense, has reached or exceeded the most recent estimate of sustainable yield, where this situation is likely to occur if present trends continue, or where groundwater resources are judged to be at risk for any reason. There are 41 GMUs, ranging from as small as 4 km2 to nearly 40 000 km2. The largest GMUs are those in the eastern part of the Murray Basin, where the initial mid 1980s definition of a GMU included a large area in which saline water was dominant. While this tends to skew data for these larger areas, and there is an argument in favour of reducing their size, in practical terms the problem has been dealt with by subdivision of the GMU into zones. Most of the management effort applied is concentrated in those zones in which low salinity water can be obtained.

UAs in NSW are those areas where the degree of management needed is less. UAs constitute the largest part of the State, ranging in size from about 15800 km2 (Clarence Morton, Oxley Basins) to 238000 km2 (Lachlan Fold Belt Province). These areas comprise those parts of the main sedimentary basins and fractured rock provinces which are not included in the GMUs, namely the Clarence-Morton, Oxley, Gunnedah, Sydney and Murray Basins and the New England, Lachlan and Olary fractured rock provinces.

Two other important areas should be noted. The Border Rivers GMU and the Great Artesian Basin Province both cross State borders. Data for both areas have been compiled by the Queensland Department of Natural Resources, using data obtained from the Great Artesian Basin Consultative Committee and Border Rivers Commission respectively. The Great Artesian Basin has been reported on the basis of 13 groundwater management units, three of which are entirely in NSW.

GMUs and UAs have been grouped and/or defined for the purpose of this Audit into province areas. The concept of groundwater provinces was thought in the 1980s to be a logical basis on which to construct a groundwater management regime, and was used as a comparative unit for the 1985 review of Australia's water resources. In the event, however, this has been found to be impractical and groundwater management units have been defined on a much more detailed basis. Their boundaries are often influenced by, and in large part coincide with, geological features, but are also in large part purely administrative. The concept of groundwater provinces on a regional scale, as suggested by the earlier work, is therefore not regarded as particularly useful, but has been used here so that some comparisons can be made with the 1985 review.

Hydrogeology

The dominating influences on the location and magnitude of groundwater resources in New South Wales are geology, geomorphology and climate. The run-off divide formed by the Great Dividing Range separates the short steep eastwards flowing rivers which flow directly into the Pacific Ocean from the western flowing rivers which have a much longer and more circuitous course to the Southern Ocean as tributaries of the Murray River.

The eastern flowing rivers have, on the whole, had a relatively short period since the last major sea level changes in which to develop, and there has been only a limited development of alluvial deposits. Where such deposits do occur, they commonly grade laterally into unconsolidated estuarine and marine deposits. Consequently the highly productive aquifer systems often associated with alluvial deposits are generally not available in association with these eastern flowing rivers. Extensive, but shallow, alluvial deposits are associated with the Hunter and Richmond Rivers, and in the former case are important sources of groundwater mainly used for irrigation. The other coastal river systems have only limited groundwater resources associated with their alluvial deposits but are used extensively as a stock and domestic source of water especially during droughts.

The most productive aquifer systems in the eastern coastal region are the coastal dune deposits, which have been extensively developed along some parts of the coast during a succession of sea level changes. Of particular importance are the Tomago Sand Beds and associated Tomaree and Stockton deposits, which provide an important part of the water supply for Newcastle and surrounding areas.

The western flowing rivers have a much longer route to the sea, with lower gradients across the western slopes and plains. Alluvial deposits have formed extensively along their valley systems, and in the case of the southern rivers, in delta areas where in past times they debouched into the eastern marginal areas of the lakes and swamps of the Murray Basin. A large proportion of these deposits formed during periods when the climate was very humid, resulting in chemical deposition of the products of erosion from the highlands. Under these conditions, quartz grains remain as an inert residual product while all other products of decomposition are soluble and removed as part of the salt load of the rivers. The outcome of this process is the accumulation of thick and extensive deposits of clean quartz gravel and sand, and it is these deposits which form the main aquifers in the westerly flowing river systems in New South Wales.

The most substantial deposits within the river valleys are in the Murrumbidgee Valley (upstream of Narrandera), the Namoi Valley, and the Lachlan Valley (upstream from Hillston), and in all these areas it is possible to construct bores with very large supplies. Pumping rates of 20 ML/day are not uncommon, and the salinity of the water is as low as 300 mg/L. Less substantial resources are available in all the other westward flowing rivers, to a varying degree. In the case of the Murrumbidgee, Murray and Lachlan Rivers, extensive deposits of coarse quartz sand and gravel have accumulated in deltas formed where the rivers left the main valley system and entered the low lying Murray Basin area. These are best developed in the Darlington Point and Hillston areas on the Murrumbidgee and Lachlan Rivers respectively, and many bores are capable of yields of 30 ML/d or more.

The alluvial deposits described above are, in terms of their geological character, superficial. That is, they form a thin veneer on some parts of the landscape, obscuring the basement rocks beneath them. Those underlying rocks are of varying character and have a very wide range of water storage and transmitting capacity. Sandstone, with residual intergranular porosity, is in general the most highly productive of them and in New South Wales they occur in a number of large sedimentary basins. By far the most important from a groundwater sense is the Great Artesian Basin. It occupies an area which covers 20% of the Australian landmass extending over four States/Territories, and its water resources are discussed elsewhere.

The Oxley Basin contains a sandstone formation, which is an extension of the main sandstone aquifer of the GAB, and although artesian conditions in it are such that bores do not flow to the surface it is possible to pump moderately large supplies of water from bores. The aquifer is extensively covered and obscured by the basalt of the Liverpool Range. Sandstone in the Clarence-Morton, Gunnedah and Sydney Basins are generally less productive than in the GAB or Oxley Basins. Stock and domestic supplies are commonly available, but bores with yields sufficient for irrigation, municipal or industrial use are rare. There are several areas within the Sydney Basin, where circumstances such as locally better permeability and/or recharge conditions in the Hawkesbury Sandstone aquifer have resulted in slightly higher pumping rates being available. Concentrated usage in some of these has led to a degree of competition locally for access to supplies.

Older fractured crystalline rocks of igneous or metamorphic origin form the landscape in large areas of the State, and have been grouped here into the New England, Lachlan Fold Belt and Olary Provinces. These rocks are intrinsically impermeable, and only attain a degree of porosity and permeability, which enables them to store and transmit water by secondary processes. Such processes may be tectonism (earth movements) which causes fracturing and jointing and consequently open spaces within the rock mass, or chemical erosion which may differentially remove some of the rock mass leaving a matrix of residual material with some porosity and permeability. In the more humid areas along the Great Dividing Range, small pumping rates sufficient for stock and domestic use and with salinity generally less than about 1500-2000 mg/L. Towards the west, as the rainfall decreases and the land slopes and elevation which control the hydraulic gradients decrease, the salinity increases gradually and is generally such that the water can only be used for stock watering and limited domestic purposes.

Available Resource

The available groundwater resources, based on estimated sustainable yield estimates are tabulated, together with usage and allocation amounts in Table3.

Use of the Resource

The estimated current groundwater usage is tabulated, together with sustainable yield estimates and allocation amounts in Table 3.

Sustainable Yield and Environmental Allocation

The following paragraphs have been adapted from the DLWC report "Sustainable Yield Estimates for High Risk Aquifers In NSW" (J Ross, 1999, In Press). They outline NSW current approach to estimation of sustainable yield.

One of the most basic pieces of data required for sensible management of a resource is the quantity of input to a system or "recharge". In the past, the quantity of recharge to an aquifer was accepted as an amount equivalent to the "safe yield" or quantity of water that could be removed from an aquifer artificially on a sustainable basis. We now understand that the "sustainable yield" of an aquifer is almost always a quantity that is considerably less than recharge so adequate provision for the environment can be made. Nevertheless, a sustainable yield figure is derived from a recharge determination. With this in mind, any sustainable yield study will always involve the determination of recharge as a first necessary step.

The following working definition has been adopted:

"Sustainable yield is that proportion of the long term average annual recharge which can be extracted each year without causing unacceptable impacts on the environment or other groundwater users"

From the above definition, it is immediately apparent that the actual "proportion" is not specifically given. This proportion will change according to each situation and is assigned differently to each aquifer system. Recharge calculations with "sustainability factors" applied to them act as interim sustainable yield figures. These "sustainability factors" are some proportion of long term annual average recharge. While adhering to the precautionary principle, sustainability factors are chosen according to level of knowledge of an aquifer system, level of use of that resource, the magnitude of perceived risk to that aquifer system and the environment, and the reliability of recharge to that system. As better understanding is developed, the sustainable yields can be adjusted accordingly. The initial figures are intended to be conservative while bearing in mind that it is most often easier to subsequently adjust Sustainable Yield values upward rather than downward. "Sustainability factors" offer protection to the integrity of the groundwater system itself and ultimately all groundwater users including the environment and ensure that neither temporary nor permanent damage to the aquifer system results from overuse.

Sustainable yield values can - and indeed will - change over time as our technical understanding of the dynamics of individual groundwater systems is enhanced as a result of more rigorous investigation and in response to changes in natural and socio-economic realities. In short, this is a commencement of a continuous process of periodic "review and adjustment" of sustainable yield estimates. It follows therefore that a set of sustainable yield figures will reflect a level of understanding that exists at a point in time. Groundwater management committees may change the sustainable yield factor to suit local conditions.

High levels of accuracy in determining sustainable yield require a degree of rigorous study that would take years if not decades to achieve. As many systems are either over-allocated or about to become over-allocated, it is not practical nor is it in the best interests to wait those decades before adopting allocation ceilings that are technically highly accurate. In short, at this stage a very high degree of accuracy is not required to commence management consistent with the philosophy of sustainability. Nevertheless, the approach applied has generated a set of figures that have been produced as a synthesis of knowledge accumulated to the present and have been adjusted according to good hydrogeological common sense and an understanding of local issues. Additionally, the approach has been conservative in the interest of resource protection but tempered with compromise recognising the need to preserve current development and acknowledging the importance of encouraging continued development where appropriate to do so.

Where rigorous numerical models have been developed and have resulted in the generation of acceptable recharge figures for an aquifer system, these values have been adopted as acceptable for use in sustainable yield determinations. In some cases systems that are similar to a modelled system have had recharge determined empirically using the modelled system as a reference.

The first question asked was therefore "Does a model exist?" If so, has it produced acceptable recharge figures? If this was the case, those recharge figures were used. If not, alternate assessment was carried out.

Most systems however, have not been modelled. In those cases, inputs (or recharge) to the system have generally been kept to rainfall and river components of recharge. (Three systems, The Lower Lachlan, The Lower Murrumbidgee, and the Great Artesian Basin have been handled differently with regard to Sustainable Yield determinations and are given separate explanation below). "Throughflow" and "underflow" have in most cases been omitted from calculations in the interest of both simplicity and conservatism. Likewise, irrigation "returns" have not been considered even though in some situations, a certain proportion of irrigated water might be expected to access the underlying aquifer.

Two equations were used to estimate recharge. Both have a limited number of terms and allow recharge values to be assigned respectively to:

Rainfall recharge was calculated simply according to assessed rainfall, area and proportion of rainfall accessing the aquifer. River recharge was estimated using an equation, which is a modified form of the "Darcy" equation that is used in the assessment of river recharge in the "Modflow" software package that models groundwater flow. The result is a "theoretical" contribution of the river to the recharge. An additional factor was applied to this result as an "adjustment" factor intended to reduce the theoretical river recharge and is set as a) the fraction of the year and/or b). fraction of river reach - that is considered as a "loosing stream". In this way an actual river recharge component is produced.

There is a strong subjective character to the results achieved by the above method. This subjective character is unavoidable because of the "general" approach to the problem at hand. Additionally, in most cases our understanding of the groundwater systems in the State is general itself and requires that a variety of assumptions be made based on similarities to known conditions. These assumptions however are made with common sense and with hydrogeological principles in mind and are therefore valid within the needs of the present situation.

Once recharge values have been estimated, some proportion of that recharge is taken as the Sustainable Yield. The setting of this proportion again introduces an element of subjectivity. As a "default" however, 70% of average annual rainfall is taken as the proportion that can be extracted form the aquifer annually on a sustainable basis. This is consistent with the situation in Victoria where 70% is the default figure. Therefore unless designated otherwise for specific reasons 70% of annual average recharge is taken as the sustainable yield of the aquifer. Similar to the terms in the recharge equations, the sustainable yield "factor" is somewhat arbitrary but does offer what is considered to be adequate protection and security to the groundwater system, environment and extractive users.

GMU - Name Total abstraction ML/y Total Allocation ML/y Sustainable yield ML/y
Alstonville Basalt 4700 8200 22000
Araluen alluvium and weathered granite 570 494 1700
Bell Valley Alluvium 1050 5918 7000
Bellinger coastal sands 2 2 2080
Belubula River Alluvium 3000 19152 6000
Billabong Creek Alluvium 2330 7461 20000
Blue Mountains 10780 2509 39000
Botany Sand Beds 3904 5859 22500
Coolaburragundy-Talbragar Valley Alluvium 1800 7189 7000
Cudgegong Vally Alluvium 3200 15769 12000
GAB - Central - NSW 6580 6580 5750
GAB - Southern Recharge 70780 70780 53640
GAB - Surat NSW 36850 36850 10100
GAB - Warrego - NSW 44390 44390 38770
Hastings river alluvium 973 999 12710
Hunter Valley Alluvium 34491 106529 57000
Inverell Basalt 1549 3015 8560
Lower Gwydir Alluvium 40762 99032 35000
Lower Lachlan Alluvium 28011 237452 94000
Lower Macquarie Alluvium 34006 154021 48200
Lower Murray Alluvium 103170 332976 136000
Lower Murrumbidgee Alluvium 184063 384376 226000
Lower Namoi Alluvium 118849 213264 95000
Macleay alluvium and coastal sands 14171 15296 29330
Mangrove Mountain 674 2336 26624
Maroota Tertiary sand 182 182 200
Maules Creek Alluvium 665 8833 7000
Mid and Upper Murrumbidgee catchment fractured rock 2004 1577 6000
Mid Murrumbidgee Alluvium 36956 50823 89000
Miscellaneous tributaries of Namoi (alluvium) 4321 14906 5000
Molong limestone 800 4000 7000
Mudgee Limestone 510 2459 2000
North Coast fractured rocks 1200 2248 80000
Orange Basalt 6400 7684 17000
Peel River Alluvium 8000 33000 10000
Richmond coastal sands 6 6 13000
Richmond River alluvium 3608 4593 68000
Southern Highlands 9762 21494 221000
Tomago/Stockton/Tomaree Sandbeds 34816 52616 45000
Upper Lachlan Alluvium 47559 174474 205000
Upper Macquarie Alluvium 11000 43127 30000
Upper Murray Alluvium 13243 40041 30300
Upper Namoi Alluvium 81800 279176 118000
Viney Creek alluvium and coastal sands 1005 1001 21000
Young Granite 7095 18010 15500
Total, Groundwater Management Units 1021587 2540699 2005964
Unincorporated Areas Total abstraction ML/y Total Allocation ML/y Sustainable yield ML/y
UA - Clarence-Morton Basin 4515 8420 427545
UA - Gunnedah Basin 4069 7293 208000
UA - Lachlan Fold Belt Province 23552 47104 428900
UA - Murray Basin 2300 2300 480000
UA - New England province 32195 92 1864544
UA - Olary Province 265 501 153000
UA - Oxley Basin 10636 19252 179086
UA - Sydney Basin 7047 5857 554637
Total, Unincorporated Areas 84579 90819 4295712

Categorisation

The estimated current groundwater usage is tabulated, together with sustainable yield estimates and allocation amounts in Table 4.

Abstraction Allocation
Category 1 (% 0f total) 44 27
Category 2 (% 0f total) 24 16
Category 3 (% 0f total) 16 7
Category 4 (% 0f total) 16 51

Joint Groundwater and Surface Water Use

During the late 1980s and early 1990s, conjunctive use of surface water and groundwater was encouraged in NSW by the issuing of licences which provided for a varying entitlement to groundwater, depending on surface water availability in any year. Licensees holding such a licence in addition to a surface water licence could, if they chose, increase their groundwater withdrawals in years when less than 100% of their entitlement to surface water was available because of low surface water resources. Arrangements varied between GMUs but in general the holder of a conjunctive licence could make up a large part of any surface water shortfall. It was useful while groundwater sources were substantially under-utilised, but became unworkable as sustainable groundwater yields were approached or exceeded. The increased groundwater use caused by such licences coincided with periods of maximum withdrawal by groundwater-only users and placed a severe strain on aquifers. Interference effects between pumping bores during irrigation periods became excessive.

Issue of conjunctive use licences has been discontinued. The conjunctive nature of surface and groundwater resources has been addressed by the development of aquifer sustainable yield estimates, which take account of river recharge. The aim of groundwater management in the GMUs is now to limit withdrawals to the sustainable yield. Some of the sustainable yield is derived from river recharge (or river losses), but withdrawals at rates which exceed sustainable yield and which would induce additional river losses will be progressively eliminated.

Potential for Development

Demand Trends

Demand in the NSW portion of the Murray-Darling basin (MDB) will remain static while ever the MDB Ministerial Council cap on water use is in place and the NSW government maintains its current approach to environmental flow management. There may be some change in the annual pattern of demand as users optimise their water use and management within the water sharing and cap bounds.

Some urban schemes within the NSW portion of the Murray-Darling basin may have increasing trends in demand due to population and industrial growth. This increased demand will be at the expense of reduced supply to low security users in that SWMA, so that total water use in the basin remains within cap limits.

Development Constraints

There is no surface water development potential within the NSW portion of the Murray-Darling basin while ever the Murray-Darling Basin Ministerial Council (MDBMC) cap on water use is in place and the NSW government maintains its current approach to environmental flow management. Surface water development can only take place via transfer of entitlements to higher value use and by improvements in water use efficiency.

Identification of the surface water development potential on the NSW coast is not possible until such time as flow management plans are developed for each of the coastal SWMAs.

The main constraint to development of groundwater resources is the extent to which they have already been developed. Allocations in the more productive aquifers have already reached or exceeded the latest estimate of sustainable yield. Further development will either cause water levels to fall to depths from which pumping is uneconomic or impossible, or induce entry of saline groundwater from adjoining areas, or both. Constraints to development of other areas are mainly the uncertainty about sustainable yield and the limit to the magnitude of individual bore supplies imposed by the physical characteristics of the aquifer formation.

Development Potential

Development potential within NSW involving additional use of resources will be confined to the NSW coast. This cannot be quantified until such time as flow management plans are developed for each of the coastal SWMAs. As this information is obtained it will be added to The DLWC website www.dlwc.nsw.gov.au

The potential for further development of groundwater resources is in general limited to some of the smaller inland river tributary valleys, some of the coastal sand and alluvial aquifer systems, and the wider areas of the unincorporated areas. Maximum withdrawal rates for individual bores are relatively low in all these cases, with maximum indicative pumping rates of no more than about 1 ML/d in most cases and in most cases less than this. There are some exceptions, such as the Oxley Basin unincorporated area, and small parts of some of the other unincorporated areas, where there is a limited potential within sustainable yield limits for the development of bores higher rate bores. Allocation in all areas where high pumping rates are available from the most productive unconsolidated alluvial aquifer systems have reached, exceeded, or are approaching, the estimated sustainable yield from those aquifers.

Forecast Use

Information on forecast use in NSW has been provided for the Murray-Darling basin and the coast. In both cases the full details of use cannot be provided at this stage. Forecast use data can only be provided when flow management plans are developed for each of the unregulated SWMAs. As this information is obtained it will be added to The DLWC website www.dlwc.nsw.gov.au

Within the NSW portion of the Murray-Darling basin the use in 2020 and 2050 will remain static at current levels. Even though the actual use in the unregulated valleys of the MD basin cannot be provided until volumetric conversion of licenses and flow management plans are completed, the management rules adopted will ensure that NSW total use within the basin does not increase above the MDBMC cap.

Categorisation in 2020 and 2050

Accurate categorisation for all SWMAs in NSW cannot be provided until flow management plans are developed for each of the unregulated SWMAs. However an attempt was made to obtain a categorisation for the catchment based on the work done for the stressed streams.

A variable P was determined for the total catchment on the basis of the combined stress classsification results from the stressed streams analysis

Total area of sub-catchments with high combined stress

P= Total area of classsified sub-catchments in basin

Categorisation was on the basis that:

Category 1 applies for 0% <= P < 30%

Category 2 for 30% <= P < 70%

Category 3 for 70% <= P <100%

Category 4 for P = 100%

Please refer to the attached Stressed Rivers Report(s) the NSW Department of Land and Water Conservation's website www.dlwc.nsw.gov.au for further information about categorisation of individual basins.

Note: there were still seven SWMAs where it was not possible to estimate a category.

Category

Number

 Category Description

Current

Number of

SWMAs (%)

2020

Number of

SWMAs (%)

2050

Number of

SWMAs (%)
1 Low Level Resource Development 21
2 Medium Level Resource Development 21
3 High Level Resource Development 2
4 Over Developed Resource 56

Environmental Water Requirements

Except for the East Coast and the uplands on the west of the divide, NSW rivers are generally small in channel capacity, flat graded, extremely sinuous with broad flood plains. Natural flows are extremely variable compared with rivers in most of the world. Generally the main channel of inland rivers carries only 10% to 50% of the flow in high floods. The rivers do not have a regular seasonal flow pattern to the same extent as the rest of the world. However, the southern inland rivers of NSW have a more regular seasonal pattern (wet winter/spring and dry summer/autumn) than the central and northern inland rivers. It is not uncommon for the lower parts of inland rivers to cease to flow for a few months during extreme droughts and have low flows for a few years during extended droughts. The periods between over-bank floods can be as long as 3 to 5 years for the southern inland rivers and up to 10 years for the northern inland rivers. On the other hand floods can occur a number of times during a year and a number of years in succession.

Australia's and NSW river based ecology has adapted to this variability, attuning itself to the extreme uncertainty and variability in stream flows and river levels. The recruitment of species generally takes place in periods of maximum food availability during over-bank flood flows of adequate duration. In extreme droughts the population probably declines to the most robust that survive in natural protected habitats. For most of the time species population is maintained by events that produce food from flood plains, billabongs and in-river benches.

Therefore the NSW Water Reform and its approach to sustainable management of surface water resources has focused on developing and implementing a series of management strategies that seek to restore some of the full range of the natural flow pattern to NSW rivers. The full range of the natural flow pattern has been altered by development within the whole catchment including, major dams, irrigation and other diversions, flood plain flow water harvesting, flood protection schemes, upland farm dams and the operational procedures used by water supply and distribution authorities and users.

A number of hydrologic measures other than average or median flows alone have been adopted as performance indicators for the development and implementation of Water Reform management actions. Action is being taken to base these measures on daily flow analysis. The measures include flow duration curves, flow sequences, ecologically significant event analysis (frequency and duration of events, duration between events).

Environmental requirements have been addressed, from a groundwater perspective, by reserving a default allowance of 30% of estimated long term average annual recharge. That is, under standard arrangements, the sustainable yield of an aquifer system is taken to be 70% of the recharge. This is in lieu of real information about the actual needs of groundwater dependent ecosystems, and will be used until such time as better information becomes available. Variation from the 70% allowance will be made in certain circumstances but to date has only really occurred in the Namoi valley where for social reasons and in the apparent absence of significant groundwater dependent ecosystems the sustainable yield has been taken as 100% of recharge.

The broad approach described above will operate at a Groundwater Management Unit and sub-unit (zone) level. Other measures to protect the environment, such as buffer zones or maintaining water levels within a band width , are used at the paddock scale to provide protection to the environment.

Water Resource Management

Surface Water Management Initiatives

The water reform process began in the 1980s, with increasing recognition of environmental needs and changes to institutional and pricing arrangements. The NSW water policy reforms, that formally began in 1995 and 1997, have been developed and implemented through a "whole of government" approach with the involvement of other key natural resource agencies

The 1995 water policy reforms aimed to:

The 1997 water policy reforms aimed to:

Groundwater Management Initiatives

Progression of water industry reforms has included a number of new approaches to groundwater management. They include:

Key Management Issues

There are a number of issues that will effect NSW's ability to achieve sustainable management of its surface and groundwater resources. The following are some of the important issues.

Data and Information Gaps

Water resource system models are the main management decision tools, which in future will need to be linked to improved economic, financial, social and environmental response models. Obviously good data and information are fundamental to the accuracy and validity of these tools. Some of the gaps in this area are:

Future Directions

Water will continue to be vital to NSW. In determining future directions it is important that water be treated as a finite, renewable resource and that there is acknowledgment that demand exceeds supply. The value of water will continue to increase. The following goals and responses have been identified for NSW's water sector future.

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