Australian Natural Resources Atlas

Natural Resource Topics

Water - South Australia - Water Resources Overview

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

Introduction

Water is a major factor influencing the development of South Australia. Most of our population lives in the temperate, southern 15% of the State and even there major natural water resources are often removed from urban and industrial demand centres. As the State developed, demand outstripped local water sources and as new parts of the State were settled, major pipeline systems were constructed to transport water to demand centres.

The southern and coastal areas of the State receive annual rainfalls ranging between 300 mm and 1000 mm. It mostly falls in winter and early spring and streams flow as a result. In summer, evaporation is high and streams tend to become a series of pools and then dry up entirely.

In the remaining 85% of the State the climate is either semi-arid or arid. Rainfall occurs sporadically and can be concentrated and intense causing both local and widespread flooding. Evaporation rates are usually high and range up to extreme in the far north. Surface water dries out very quickly.

In their natural state, steams, floodplains and wetlands tend to be both abundant and diverse in flora and fauna. Occasional algal and bacterial concentrations occur naturally. Wetlands provide rich breeding sites and are refuges during dry periods. The natural ecosystems of stream beds, banks and floodplains depend on a wide range of stream flows and the steady contribution of groundwater where it is present.

Development often has adverse impacts on natural ecosystems. Monitoring has indicated that the health of water ecosystems in developed catchments has been degraded by pesticides, diffuse pollution, gross changes in natural stream channel configuration, riparian vegetation changes and altered stream flows.

The bulk of the State?s surface water is fresh to marginally saline while high stream flows are often turbid. Surface water can be brackish when salt is flushed from drier catchments or is concentrated by summer evaporation. Streams in highly developed catchments - urban catchments for example - tend to have elevated concentrations of nutrients and heavy metals and are turbid. This degrades them for most uses. Streams in catchments covered with natural vegetation usually supply the best quality water.

Increased deep rainfall infiltration to groundwater has been a consequence of land clearing in agricultural areas. As groundwater levels rise toward the surface, widespread increases in soil salinity occur taking land out of production and increasing stream salinity. To some extent this process can be controlled locally by vegetation retention, water extraction and drainage.

In more than half the State groundwater is accessible all year round and, as a consequence, it is the major natural water source over much of SA. By nature, groundwater resources, which exist in shallow or confined porous media, or in fractured rocks, are extremely variable. Porous media aquifers generally provide the larger volumes of good quality water whereas fractured rock aquifers have characteristically lower yields. While low-yielding and localised in extent, fractured rock aquifers - which underlie 40% of the Australian continent - are often the only source of permanent water in the drier regions. Quantity and quality vary between regions. Large volumes of good water are available in some areas. In others it may be salty and difficult to access.

Apart from providing a resource in dry regions, groundwater discharging into streams in those areas can extend stream flow into summer and help sustain water-dependent ecosystems through dry periods.

Water is a finite and scarce resource in SA and the appropriate management response is to put in place arrangements that will ensure available water resources are used in an ecologically sustainable manner. Where State water resources are seen to be subject to increasing use pressures, or their environmental values are degrading, the Water Resources Act, 1997 allows the area to be proclaimed, users licensed and requires the implementation of water allocation plans to help regulate future development. The water allocation plans may also allow water rights or entitlements to be traded.

Legislative Framework

A number of South Australian Acts impact on water resource management in South Australia. The two main Acts are the Water Resources Act 1997 and the Environment Protection Act 1993. Other relevant Acts are the Native Vegetation Act 1991, Pastoral Land Management and Conservation Act 1989, Soil Conservation and Land Care Act 1989, Development Act 1993, and Local Government Act 1999.

The Water Resources Act 1997 provides for the management of water resources through a hierarchy of water plans prepared and regularly reviewed through a comprehensive process of community involvement. The plans include:

· The State Water Plan, sets the strategic directions for water resources management throughout the State.

· Catchment water management plans, prepared by Catchment Water Management Boards to establish, and provide for the implementation of, catchment priorities.

· Water allocation plans, prepared for prescribed water resources by either Catchment Water Management Boards or water resources planning committees.

· Local water management plans, prepared by local councils for water resources within the relevant council?s area.

The purpose of the State Water Plan is to set out policies for achieving the objects of Water Resources Act 1997 throughout the State. In addition, the State Water Plan must:

(a) Assess the state and condition of the water resources of the State;

(b) identify existing and future risks of damage to, or degradation of, the water resources of the State;

(c) include proposals for the use and management of the water resources of the State to achieve the object of the Act; and

(d) include an assessment of the monitoring of changes in the state and condition of the water resources of the State and include proposals for monitoring these changes in the future.

The State Water Plan is the peak water plan and provides the policy framework for water resources management and use throughout the State. Catchment water management plans, water allocation plans and local water management plans provide the regional and local focus. The Water Resources Act 1997 has a focus on terrestrial water resources and is not directly concerned with the management of estuaries or marine water environments. There are however, important biological and hydrological linkages between rivers, streams and, in some cases groundwater systems, estuaries and the coastal marine environment. The South Australian Government?s directions and strategies for estuarine and marine management, are set out in the 1998 document, Our Seas & Coasts - A Marine and Estuarine Strategy for South Australia.

Water plans developed pursuant to the Water Resources Act 1997 must be consistent with the State Water Plan. In this process, the importance accorded to the State Water Plan by the Water Resources Act 1997 cannot be over-stated. For example, decisions by the Minister or the relevant authority to grant permits for water-affecting activities must be consistent with the State Water Plan and any other relevant water plan. Similarly, decisions by the Minister or the relevant authority to grant, vary or transfer water licences must be consistent with the relevant water allocation plan, which itself must be consistent with the State Water Plan.

All water plans must be reviewed regularly. The Water Resources Act 1997 sets out both the required frequency and the conditions for the reviews - such as maintaining consistency with the State Water Plan.

COAG Compliance

South Australia meets the three major areas for reform set down by the COAG guidelines:

1. Both the repealed Water Resources Act 1990 and the current Water Resources Act 1997 provide a well defined and easily understood system of legal rights to access and use of water resources. This is achieved through the establishment of prescribed water resources and a declaration that the use of, and access to, those resources is under the control of the Minister.

2. Within the Water Resources Act 1997, there are provisions which define water licences as the holders? personal property; not associated with the land title and fully tradeable.

3. Protection and restoration of the health of water resources and dependent ecosystems is facilitated through catchment management and water allocation plans explicitly providing water for the environment. The Act recognises that a healthy environment is inextricably linked to, and underpins, sustainable economic development.

The water allocation plans must also include the needs of downstream users and define the sustainable limit of the water resource. Where the environmental impacts of water use are not well understood, the Act requires a precautionary approach to be adopted and the knowledge base improved through defined programs of monitoring and assessment.

Water Industry Structure

The water industry in South Australia is principally serviced by four authorities.

· The Department for Water Resources

· The Environmental Protection Agency

· South Australian Water Corporation

· The Department of Human Services

The Department for Water Resources (DWR) is the lead agency in the State for water resources management and regulation. DWR is responsible for the administration of the, Groundwater (Border Agreement) Act 1985, Murray-Darling Basin Act 1983 (and Agreement) and the Water Resources Act 1997 (WR Act). DWR also provides support for the inter-agency State Water Policy Committee and is responsible for leading negotiations towards the implementation of inter-jurisdictional arrangements for the Great Artesian and Lake Eyre Basins.

There are seven Catchment Water Management Boards

· Torrens

· Patawalonga

· Northern Adelaide and Barossa

· Onkaparinga

· South-East

· River Murray

· Arid Areas

Catchment Water Management Boards (CWMBs) are responsible for the protection and sustainable development of water resources, and are required under the WR Act to prepare a catchment water management plan and, where necessary, water allocation plans for prescribed areas within their boundaries. These plans must include information regarding the quality and quantity of the water resource under of the board?s jurisdiction as well as the health of dependent ecosystems.

The Environment Protection Authority (the Authority) has responsibility under the Environment Protection Act 1993 (EP Act) for the State of Environment Report. There is a requirement under the EP Act to provide for monitoring and reporting on environmental quality on a regular basis to ensure compliance with statutory requirements and the maintenance of improving trends in environmental quality. In line with this requirement, the Environment Protection Agency (the EPA), the service arm of the Authority, has developed an ambient water quality monitoring program covering inland surface waters, underground waters, and marine and estuarine waters.

The South Australian Water Corporation (SA Water) has a responsibility to ensure that potable water supplied to customers meets the national safety guidelines for drinking water. SA Water and the Department of Human Services have agreed levels of service with regular reporting on compliance. SA Water is also required to monitor the quality and quantity of discharges from sewage treatment works to receiving water bodies. Monitoring results are reported to the EPA and Department of Human Services (DHS) and are publicly available via the EPA.

The Public and Environmental Health Act, 1987 (PEH Act) deals with protection of water supplies and provides for offences for pollution of water and control of waste water, particularly in unsewered areas. The PEH Act is administered in conjunction with local government. The Health Aspects of Water Quality Committee (HAWQ), with representatives from DHS, SA Water, the EPA and the Local Government Association, sets the broad policy framework for drinking water quality.

Surface Water Resource

Reporting Units

For this Audit, the basins as designated by the Australian Water Resources Council (AWRC) have been adopted in South Australia as a reporting unit (figure 1). A number of these basins have been further subdivided to distinguish between the range of development existing within the State. All reporting units are referred to as Surface Water Management Areas (SWMA's) of which a total of 34 have been defined.

Hydrology

The mean annual streamflow generated within the State is 1940GL, and 9300 GL is the mean flow entering the State. The Murray River discharges 7220 GL of this external supply, with the balance entering the north of the State from Queensland and the Northern Territory via the Lake Eyre Basin streams.

River flows in South Australia are extremely variable, showing both a seasonal pattern and a substantial annual variability of discharge. The seasonal distribution depends on catchment location. In the southern areas the majority of the average annual discharge occurs in the five-month period from July to November. To the north runoff is mainly driven by thunderstorm events and a greater proportion of runoff occurs from very short duration events.

Most streams in the State are ephemeral and often flow for less than 6 months of the year. However, most have areas of permanent water, either in deep pools, which reflect the regional ground water levels, or localised areas of low base flow usually supplied by local aquifers. The magnitude of the permanent base flow varies from year to year depending on the rainfall of previous seasons. It is common to see a memory going back five years to a wet season.

The more reliable streams are those rising in the Mt Lofty Ranges near Adelaide and the drains and streams in the southern part of the South-East region of the State. The Mount Lofty Ranges provide catchment for Adelaide?s domestic water supply, but the surface resources of the South-East, with the abundance of good quality groundwater in the region, have not been utilised to any large degree.

The Murray River, with its headwaters in the Eastern States, provides the State?s most reliable resource. Its reliability is critical for ensuring the sustainability of Adelaide?s water supply, in some years providing more than 90% of Adelaide?s requirements.

Surface water irrigation users have adapted to the variation of supply by growing horticultural crops such as vines, fruits and nut trees. While many of these crops receive regular irrigation from reliable sources such as the Murray River, they are also grown in other areas where they can survive over periods of river drought. Irrigation rates vary greatly depending on the availability of water. Irrigation water is generally supplied from individually owned farm dams which, without appropriate constraints, could be designed to impound at least the mean annual runoff from the catchment upstream.

Available Resource

Internally-sourced surface water resources in South Australia are limited and occur predominately in the Mt Lofty and Flinders Ranges, and in the South East of the State.

The States? major surface water resources are in the Murray Darling and Lake Eyre Basins, the catchments of both extending beyond the State?s borders.

Due to a diverse range of harvesting methods and the acceptance of a high risk of failure of farm dam supplies in South Australia, it has not been possible to estimate the total annual divertible surface water resource. It is likely external factors such as dam interference between neighbours will influence the estimate greatly. Experience suggests that in a rural environment, once the volume of water trapped exceeds 20% of the mean annual flow, significant community concerns are raised. These concerns have led to the prescription of the surface resources of the Barossa and Clare Valleys.

The divertible yield has been assumed equal to the sustainable yield, which has been determined as the maximum volume of water that can be diverted after taking account of in-stream environmental water requirements. In South Australia proposed policy suggests that the total storage capacity of farm dams allowed in a catchment should not exceed 50% of the median runoff from private land. Of the 50% allowed for farm dam capacity, only half of this volume is considered to be able to be diverted for use annually, with the other half being lost to evaporation, seepage and dam overflow or not available during periods of stream drought. Based on this, the total sustainable yield of the resource generated within the State is estimated to be 300 GL, or 15% of the mean annual streamflow. Of the sustainable yield, 50 % (or 7.5% of the mean annual streamflow) has already been developed for use.

The Adelaide metropolitan catchments are fully committed with a developed yield of 130GL far exceeding their sustainable yield of 47 GL.

The Murray River is heavily committed with a developed yield of 736 GL (licensed) and a current use of 595 GL. The use is currently 84% of its sustainable yield of 704 GL, defined by the Cap, imposed by the Murray Darling Basin Commission.

Developed Use and Allocation

Water allocations apply to only those water resources prescribed under the Water Resources Act.

The total volume of surface water allocated for use in South Australia is 740GL. This allocation volume is divided into:

· 736 GL, the sum of individual water allocations in the Murray River, noting however that the total use is limited to 704 GL as a five year average. It is sourced from the other Murray Darling states upstream. This water is most commonly drawn directly from the River as needed.

· 4.2 GL of surface water allocated in the Barossa and Clare prescribed areas. Water is trapped in surface water storage over winter months for use over summer, and is licensed by defining the farm dam volume, the crop area and crop type. Aquifer recharge and recovery makes up a small proportion of the allocation.

In a regional sense the allocation for the environment is inferred, as the amount is not allocated. The Water Resources Act requires that a water allocation plan for a region must firstly define the amount of water needed by the environment before allocation is made.

At present, 750 GL of surface water is used in South Australia annually. This represents 75% of the sustainable surface water resource yield available to the State.

Of the surface water use in South Australia, irrigation accounts for 64%, or 480 GL, of the total extracted. Urban and industrial use accounts for the remaining 270 GL. The level 1 distribution of surface water use is shown in Figure 2.

Pie chart of Surface Water use in SA

Figure 2 Level 1 use categories for surface water in SA

Water Supply Systems

There are three major surface resource reservoir water supply systems in the State. These are the Adelaide Metropolitan, the Mid-North reservoirs and the Tod River systems. Metropolitan water supply reservoirs are located in the Torrens, Onkaparinga, South Para, Little Para and Myponga catchments. They have a combined capacity of 200 gigalitres and provide on average 60% of Adelaide?s water supply. The Tod reservoir has a capacity of 11.3 gigalitres and supplies 2.5 gigalitres/year for domestic use in the Eyre Region. The Mid-north reservoirs of Baroota, Bundaleer and Beetaloo are interconnected with the Morgan-Whyalla pipeline system from the Murray River. Since the pipeline system has been filtered, the Mid-North reservoirs have not been greatly drawn upon.

In addition to the reservoir systems, South Australia also has a comprehensive network of pipelines throughout the State sourced from the Murray River. There are 5 major domestic water pumping stations on the River located at, Morgan, Swan Reach, Mannum, Murray Bridge and Tailem Bend. Morgan and Swan Reach pumping stations supply 34GL/year to the mid-north and northern areas. Mannum and Murray Bridge pumping stations supply on average 40% of Adelaide?s demand, rising to 90% in dry years. The Tailem Bend pumping station supplies 3 GL/year to the South-East of the State.

Categorisation

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

Category Number Category Description Number of SWMAs (%)
1 Low Level Resource Development 22 ( 64% )
2 Medium Level Resource Development 6 ( 18% )
3 High Level Resource Development 0 ( 0% )
3* Development equal to Sustainable Yield 1 ( 3% )
4 Over Developed Resource 5 (15%)

The over-developed management areas include:

All of these SWMAs include large reservoirs which supply the Adelaide metropolitan area.

Groundwater Resource

Reporting Units

Groundwater abstraction, allocation and use information has been reported at three levels- Groundwater Management Units (GMUs), Unincorporated Areas and Provinces. Groundwater Management Units have been defined in accordance with the current groundwater management practices applied by the Department for Water Resources. Groundwater Provinces are based on the principle hydrogeological basins within South Australia. The Unincorporated Areas comprise the areas between the GMUs and the Province boundaries. In total 51 GMUs have been reported, including 15 Unincorporated Areas.

Only 23 of the GMUs are prescribed wells areas, which are the only areas within the State where allocations apply. In addition there are 3 ?Notice of Restriction? areas which may be prescribed in the near future.

Hydrogeology

South Australia has a high proportion of groundwater to surface water use because of its generally low and variable rainfall. Currently groundwater accounts for 430 GL (35%) of the 1200 GL of use in South Australia. The most productive aquifers are generally Quaternary and Tertiary sedimentary limestone in the higher rainfall areas, which yield supplies of up to 200 L/s. Sedimentary aquifers also supply good quality groundwater in semi-arid and arid environments. Fractured rock aquifers yield up to 30 L/s with salinities mostly increasing to the north as rainfall decreases.

Available Resource

It is estimated that there is currently 380 GL of groundwater use in SA, the majority of this is for irrigation supply. Major use areas are:

The 11 GL defined for the Great Artesian Basin is the known industrial/mining use only. Environmental flows maintaining mound springs and flowing wells make up the greatest proportion of "use" from the basin.

Use of the Resource

Current usage of the resource is summarised in figure 3

Pie chart of Groundwater use in SA

Figure 3 Level 1 use categories for groundwater

Sustainable Yield and Environmental Allocation

The determination of sustainable yield for each Groundwater Management Unit has been made with due consideration of the environmental impacts. Current government policy allows for variation of the sustainable yield if a detrimental impact becomes apparent.

Categorisation

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

Category Number Category Description Number of GMUs (%)
1 Low Level Resource Development 19 ( 37% )
2 Medium Level Resource Development 12 ( 23% )
3 High Level Resource Development 6 ( 12% )
3* Development equal to Sustainable Yield 12 ( 24% )
4 Over Developed Resource 2 ( 4% )

The Northern Adelaide Plains is the only over-developed management units defined. In the remainder of prescribed areas allocation of the groundwater resource is maintained on or below the sustainable yield of the aquifer.

Those areas where current development (use) is on or near the sustainable yield include

Category Number Category Description Number of GMUs (%)
1 Low Level Resource Development 0 ( 0% )
2 Medium Level Resource Development 5 ( 19% )
3 High Level Resource Development 7 ( 26% )
3* Development equal to Sustainable Yield 13 ( 48% )
4 Over Developed Resource 2 ( 4% )

Joint Groundwater and Surface Water Use

There are two areas of the State - Barossa Valley and Clare Valley - which are prescribed for both surface and groundwater resources. Studies are currently underway in these areas, examining the potential of recharging aquifers with local stream flow and reclaimed sewage effluent.

Artificial recharge has been successfully used to supplement aquifer supply in the Angas Bremer groundwater prescribed area for many years and presently there are 26 ASR trials being carried out in the Barossa Valley. The potential and risk of artificial recharge of sewage effluent and stormwater is currently being examined in the Northern Adelaide Plains and McLaren Vale with a view to reuse of the winter discharges of sewage effluent to the ocean. This carries the added benefit of reducing the environmental impact to our coastal marine environments.

Rules for aquifer recharge are currently in their developmental stage. Currently, credits for artificial recharge are recognised in Angas Bremer, Barossa Valley and Clare Valley. A licence allocation is granted for a proportion (ranging from 60 to 100%) of the measured water recharged.

In many areas of South Australia it is common for irrigators to have more than one source of water. The farm dams often provide the better quality water, but at a lower reliability than local groundwater. The mixing of the two waters provides the optimum supply. Alternatively the use of surface water when it is available allows the recovery of the groundwater for use during stream-drought years.

Streamflow from the Mt Lofty and Flinders Ranges often occurs rapidly, and the diversion of some of this flow to settlement ponds and thence to underground aquifers (both alluvial and fractured rock) could supplement current groundwater extractions that are close to sustainable limits. The lower salinity stream flows could also be used to improve the quality of saline groundwater.

Potential for Development

Demand Trends

The most prominent development opportunities are seen to be:

? Improved management and deployment of current extractions of about 1 240 GL/y of our water resources. Improved management of irrigation use, the major water use, is estimated to have the potential to at least double the productivity of current water use by better meeting crop requirements with water applications and by choice of higher value crops where water quality and other conditions permit.

? New sustainable development of a further 925 GL/y could be achieved provided that appropriate uses and management regimes can be established for such development. South East groundwater contributes about 75% of water that might be developed. Unused irrigation water of about 70 GL/y within the River Murray Cap makes up about three quarters of the surface water with potential for development.

? Unused allocations can be developed within the sustainable usage limits of water resources. River Murray water resources and most of the South East groundwater are, effectively, fully committed to allocations. However, there is still considerable scope for further development of these water resources through improved irrigation efficiencies and management

Table of Contents

Development Constraints

The constraint on development over much of South Australia is primarily one of availability of suitable quality water. Where significant volumes of water are available, such as the South East of the State, the Mt Lofty Ranges and the Murray River, much of this has already been allocated.

However, in many areas, even where the available resources are fully allocated, they are not always fully used. In some cases, water is not used as efficiently as modern technology and best practice management techniques enable. It is clear that there is scope for further economic development within sustainable water limits in South Australia. Water resources management aims to ensure sustainable development of our water resources, to underpin a secure environmental, economic and social future for the State. There is a strong demand for water to service economic development in irrigation farming (eg. viticulture and horticulture), mining and related industry. More productive use of our water assets will increase the benefit derived from them by South Australians.

Cost is not considered to be a major constraint on the development of local resources. This is because development is predominately on the small farm scale utilising farm dams and individually owned bores.

Water quality, particularly salinity, may, in the longer term, constrain development. Extensive clearing in the agricultural areas of the State has led to land and watercourse salinisation and erosion of catchments and stream beds with consequential impacts on the productivity of the land and the health of streams.

There are no State proposals for large infrastructure development such as reservoirs, but increasing use is being made of existing pipeline infrastructure to supply water from the River Murray to areas where it has a greater value. Use of River Murray water is dependent on allocations being available to transfer and on capacity in the pipelines.

Water Availability

In the North of the State, the available pressure head limits resource use from the Great Artesian Basin. Inappropriate development or use of the highly-valued water supplies and ecosystems of the Lake Eyre Basin and Great Artesian Basin (which are vulnerable to unsustainable development) is an issue that requires Interstate agreement and planned management measures.

In the Mid to Far North reliable surface water resources are confined to the vicinity of the Flinders and Northern Mt Lofty Ranges. Groundwater of quality suitable for irrigation is generally limited to fractured rock or small alluvial basins. Groundwater salinity is extremely variable and is most often too high to support irrigated agriculture. Surface water, while of generally better quality, is less reliable and is only used for irrigation in the higher rainfall areas. Construction of farm dams and use of groundwater resources can have significant impacts on the environmental streamflow requirements and development must be carefully controlled.

While surface and groundwater development is continuing in the Mt Lofty Ranges there is increasing pressure for controls to be introduced particularly in catchments which are already heavily used for Adelaide?s water supply. The Mount Lofty Ranges is subject to development that can pollute its streams. The area has also undergone substantial farm dam development and suffered extensive stream ecosystem degradation. Significant water quality impacts have been measured in the Metropolitan water supply catchments, often referred to as the watershed. Groundwater in the Ranges exists mainly in fractured rock aquifers or small alluvial basins. These aquifers are often small in extent with little known of their sustainability. Apart from potentially damaging the aquifer, over exploitation of these resources can also impact on the environmental flow requirements by reducing baseflow and permanent water in the streams. The large alluvial basins of the Northern Adelaide Plains and the Willunga Basin are already fully utilised.

The Murray River in South Australia is fully allocated with the divertible yield limited by the MDBC Cap. Development of this resource can be achieved by improved efficiencies in water and developing more sophisticated water markets to encourage the highest and best use of the resources. In the longer term water quality may effect the development and value of the River. It is subject to increasing salinity levels and its ecosystems, including the floodplain, have been significantly altered. Flow reduction, change in flow patterns and pollutant discharges have led to symptoms of degradation, such as the constriction and closure of the Murray Mouth and more frequent blooms of nuisance algae.

The Mallee and South East of the State have significant groundwater reserves for potential development. While the sustainable limits of the aquifers in the area are high, the ultimate development may be limited by increasing salinity and availability of land suited to development. Drainage in the area is providing an increasing surface water resource. To date little use is made of this resource and salinity may limit its full development. Development of this resource can be achieved by improved efficiencies in water use and developing more sophisticated water markets to encourage the highest and best use of the resources.

Development Potential

The State has sufficient water for our present and future needs, provided that we are careful, flexible and innovative in the use of our water resources and water infrastructure.

Three regions of the State - the South East, the Murray River and the Mt Lofty Ranges - are defined as having significant potential for development if managed carefully. In addition the Great Artesian Basin does offer development potential in conjunction with the capping of flowing wells.

No attempt has been made to determine the development potential of the Mid to Far North areas of the State. Large volumes may be available for relatively short periods on an infrequent basis, requiring a different approach to risk management for irrigation enterprises and the protection of environmental flow regimes. Environmental flow requirements of a number of streams in the area are currently being assessed.

Current management allows the continuing development of farm dams in the Mt Lofty Ranges watershed, which supplies Adelaide?s water supply. While development continues in the watershed it is assumed, in this assessment, that the resource available at the domestic supply reservoirs will decrease. To compensate, more water must be pumped to Adelaide from the River Murray.

The salinity of the groundwater in some areas of the South East already is approaching levels which are considered marginal for irrigation. It is possible that further development may decrease the water quality further, which may restrict the full development of the resource. This impact has not been considered in this assessment.

Forecast Use

Current Use GL/year Forecast Year 2020 Forecast Year 2050

Mt Lofty Ranges

South East

Murray River

Total

192,000

287,600

595,000

1,074,000

212,000

749,000

704,000

1,664,000

239,000

1,056,000

704,000

2,000,000

The potential future development defined of 925 GL is split between groundwater,710 GL, and surface water,215 GL.

Categorisation in 2020 and 2050

Current

ML/year

Category

Current

Use 2020

ML/year

Category

2020

Use 2050

ML/year

Category

2050
Mt Lofty Ranges
501 Fleurieu Pen 1360 1 6000 1 10000 2
502 Myponga 10900 4 10900 4 10900 4
503 Onkaparinga 53600 4 53600 4 53600 4
504 Torrens 36300 4 36300 4 36300 4
505.2 Gawler 21800 4 21800 4 21800 4
505.3 Little Para 8300 4 8300 4 8300 4
503 Willunga 0 1 400 1 1300 2
513 Kangaroo Island 2400 1 4300 1 8800 2
426 Murray Eastern Streams 6700 1 7500 1 8700 2
S1&S2 Gawler (GW) 5200 3 5550 3* 5550 3*
S14 Mt Lofty Ranges (GW) 25000 2 35000 3 47000 3*
S18 Angas Bremer (GW) 1700 2 2400 2 5000 3*
S9&S10 Nthn Adel Plains(GW) 18400 4 18400 4 18400 4
S7 Kangaroo Island (GW) 0 1 1250 3* 1250 3*
Otway and Murray Basin
S36 Lacepede-Kongorong 84700 1 400000 3 608500 3*
S34 Comaum-Caroline 33800 2 65000 3 85400 3*
S28 Naracoorte 41000 2 65000 3 81700 3*
S26 Padthaway 24200 3 30000 3 35100 3*
S24 Tatiara 60900 3 74000 3 82000 3*
S30 Tintinara 25500 3* 25500 3* 25500 3*
S20 Mallee 17500 2 38000 3 52800 3*
239 Surface Water 0 1 50000 2 85000 3*
River Murray
595000 3 704000 3* 704000 3*

Environmental Water Requirements

The South Australian Government is committed to ensure all water resources are used in a sustainable manner. The State Water Plan provides a suite of policy principles that addresses protection and management of the ecological values of water-dependent ecosystems. The purpose of these principles is to provide guidance and direction to the authorities preparing water plans on how to deal with these issues in an integrated manner - whether they be Catchment Water Management Boards, water resources planning committees or local government.

The State Water Plan recognises that there is a range of ecosystems associated with, and dependent on, water. These include watercourses, riparian zones, wetlands, floodplains and estuaries.

The condition of many of these ecosystems in South Australia has declined and is at risk of further deterioration. Much of this change is as a result of past development and practices which have left the current generation with a legacy of degraded waterbodies and water-dependent ecosystems that require remedial action.

The State Water Plan also requires a monitoring strategy to be implemented to assess the changes in the condition of the water resources of the State. Ongoing monitoring and evaluation are identified as vital procedures to allow measurement of the change in condition of the resource. The success of policies within management plans will be measured by how they meet catchment, stream health and economic objectives.

The principles of ecologically sustainable development will be adhered to. Until the true environmental flow requirements of streams can be defined, a precautionary approach to water resources development is advocated.

Water Resource Management

Surface Water and Groundwater Management Initiatives

The management goals and objectives for surface and groundwater management are comprehensively defined in the Water Resources Act,1997 and the State Water Plan.

The surface water resources within the State are required to be managed in such a way that those who rely on the resource will obtain the best environmental, social and economic benefit from it without compromising the ability of future generations to enjoying the same benefits. The South Australian Water Resources Act 1997 places prime importance on protecting water resources against the detrimental effects of use and development and on preserving ecosystems that depend on them.

The State Water Plan, endorsed by the Minister, sets the strategic directions for water resources management throughout the State.

Catchment Water Management Boards are required to prepare catchment water management plans to establish, and provide for the implementation of catchment management and development priorities. Within prescribed areas, Catchment Water Management Boards or Water Resources Planning Committees are required to prepare water allocation plans defining how water is to be allocated. Water allocation plans must ensure that the environmental flow requirements are met before water is allocated for commercial use. Local water resource management plans can be prepared by local government where they elect to do so. Such plans allow for the development of management strategies in areas where Catchment Water Management Boards do not exist.

These plans must be consistent with the State Water Plan.

Key Management Issues

The State Water Plan defines the key water resource management issues to be;

· Ensuring sustainability, with the availability of water of sufficient quantity and quality for human use and the environment seen as fundamental to maintaining and improving the quality of life of all South Australians;

· South Australia?s water is precious and must be managed and used according to the principles of ecologically sustainable development under which water is to be used so as to maximise its economic, social and environmental returns on a sustainable basis;

· South Australia?s water resources must be managed in an integrated manner with all other natural resources;

· South Australians have the right to be informed, consulted and involved in the management of water.

Water resources management aims to ensure sustainable development of our water resources, underpinning a secure environmental, economic and social future for the State.

The most significant threats to our water resources are:

? The Mount Lofty Ranges is subject to development that can pollute its streams. The area has also undergone substantial farm dam development and suffered extensive stream ecosystem degradation. Significant water quality impacts have been measured in the metropolitan water supply catchments.

? The River Murray, also a major water source for urban and irrigation uses, is subject to increasing salt loads from interstate and from within South Australia which will lead to significant increases in salinity in the coming decades. Its ecosystems, including the floodplain, have been altered by significant flow reduction, change in flow patterns and pollutant discharges that have led to symptoms of degradation, such as constriction and closure of the Murray Mouth and more frequent blooms of nuisance algae.

? The level of development of many of our prescribed groundwater water resources is approaching or has reached the sustainable limit, and usage has been restricted to this level. In some cases, the sustainable limit has been exceeded, causing unacceptable rises in salinity and drops in water level or pressure.

? Inappropriate development or use of the highly-valued water supplies and ecosystems of the Lake Eyre Basin and Great Artesian Basin, which are vulnerable to unsustainable development, require planned management measures and interstate agreements to be negotiated to manage this risk.

? Extensive clearing of the agricultural areas of the State has led to land and watercourse salinisation and erosion of catchments and streambeds, with consequential impacts on the productivity of the land and the health of streams.

? Metropolitan estuaries and coastal marine environments have been impacted by polluted stormwater and effluent discharges to Gulf St Vincent. Polluted stormwater has also altered flow regimes in our rivers.

Data and Information Gaps

Perhaps the most fundamental issue for sustainable groundwater management is defining what constitutes a sustainable yield that can be extracted from an aquifer for beneficial or consumptive use. In the past, groundwater management in many parts of Australia was based upon the notion that annual extraction equal to the mean annual recharge was sustainable. This is now generally accepted as being inappropriate, as it takes no explicit account of environmental water needs, water quality impacts, and the spatial and temporal distribution of extractions. Data and information gaps are recognised as:

1. In calculating sustainable yield, factors that need to be considered include, the state of technical knowledge about the aquifer and its recharge processes, the level of groundwater utilisation and risks to the groundwater system and dependent ecosystems from overuse and pollution. The amount of available data and technical knowledge varies significantly across the State. Prescribed areas typically have good water level and water quality monitoring information but often lack accurate usage and discharge data. In the remainder of the State the availability of all this type of information can be sparse.

2. It is generally accepted that there are at least five types of ecosystems that are dependent on groundwater. These are phreaphytic vegetation, wetlands, river baseflow systems, cave ecosystems and aquifer ecosystems. The presence of these ecosystems varies across the State, but all have biodiversity and other values. The cave and aquifer ecosystems are poorly understood but often contain unique and ancient fauna that has scientific value especially in aiding understanding of evolutionary biology. The importance of groundwater to surface water ecosystems also cannot be understated and current environmental studies have indicated that the maintenance of permanent water is a prime environmental flow requirement. It is clear that more information on a Statewide level is required in this area. This will probably require conjunctive surface and groundwater monitoring.

3. In the prescribed wells areas there is a need for some further refinement of the monitoring programs and additional research to refine the groundwater models used to determine sustainable yield. Additional assessments include investigating the linkages/leakage between aquifers, refining recharge rates, pumping tests for yields from specific aquifers and interactions between surface and ground water resources.

4. More information is required to develop an understanding of area specific groundwater processes, including recharge and discharge and water movement within aquifers. This would allow better management of natural variations of the resource and better definition of the sustainable yield.

5. Fractured rock aquifer systems, such as those of the Mount Lofty Ranges, are complex and only scant information is available on them. Assessments are mostly reliant on the basic bore-hole data. Sustainable yield assessments have been carried out for areas with high levels of groundwater dependent irrigation, but there is a need to extend these assessments to other catchments and to refine them (eg. surface and groundwater interactions, irrigation application rates, current yields and recharge rates).

South Australia has a stream-gauging network for major catchments in the wetter southern areas of the State and a small selection of arid streams in the north of the State. The location of some gauging sites, the lack of information from drier catchments and the need for good spatial and temporal data on the impacts on flow

regimes of extractions, discharges and storages, has frustrated attempts to determine water balances and catchment responses to development in some areas. In addition, difficulties have been experienced in obtaining useful records while using established techniques in some arid catchments. Data and information gaps are recognised as:-

1. The understanding of environmental water requirements for ephemeral streams. Lack of information has led to the advocacy of a precautionary approach to water resources management and use. Monitoring and assessment programs to develop an understanding of these relationships are currently being developed. Data and information gaps here are recognised as:

· There is a lack of performance monitoring of environmental protection strategies such as environmental flow. A monitoring strategy is required to be developed to -

Ø produce a basic inventory of aquatic ecosystems of the State;

Ø describe in quantitative terms the environmental impacts and assess the water allocation plans of the State?s surface water prescribed areas; and

Ø maintain a watching brief over the remaining surface resources of the State.

· Ecosystems of both surface and groundwater are not well understood.

· Baseline information of aquatic habitats is limited to certain catchments. There is little information defining their relationship with stream flow.

· There is no ongoing hypothesis testing monitoring and baseline monitoring.

· There is little baseline information on the condition of estuarine and marine ecosystems and on the impact of stream regime change and pollutant loads.

2. A better coverage of the State with stream water quality and quantity monitoring stations is needed, particularly in the Mid-north to Northern areas. The present network was designed to focus on reticulated water supply initially, with broad-scale monitoring begun in the 1980s, as part of the national program for water resources assessment.

3. A more intensified salinity monitoring strategy is required recognising the threat to water resources from dryland salinity. Salt balance and salinity trend estimation will require measurement of salinity at existing and new streamflow and rainfall gauging stations.

4. Rainfall data is frequently used to model both surface and groundwater responses where there is insufficient primary data. The locations of existing rainfall sites are frequently unsuitable for this purpose, particularly for smaller localised studies.

5. Most South Australian catchments are no longer pristine and their response to rainfall is affected by changes in vegetation and land management. Data sets collected from catchments with significant native vegetation are required for comparison with those from developed catchments.

6. More detailed streamflow information at the sub-catchment level is needed in more intensively developed areas of the Mt Lofty Ranges. Monitoring sites are needed to identify the relationship between ground and surface water and the impact of land use and management on streamflow.

Most significant water extractions from water resources subject to prescription are required to be licensed under the Water Resources Act 1997. A water allocation, notionally a volume of water that is allowed be taken annually, is stated on the licence. The volume of allocated water actually used is either measured by water meter or estimated from the area of irrigation, using theoretical water application rates. Data and information gaps are recognised as:

1. Accuracy of groundwater use estimates. Many prescribed areas, particularly those in the South East of the State, are not metered and water estimation is based on crop areas. Estimates do not take into account wide variations in water management and without an accurate measurement of water use the sustainable resource can only be estimated. Outside of the prescribed areas estimates of irrigation, stock and domestic water use are made on local knowledge.

2. Accuracy of surface water use estimates. A small area of the State is prescribed for surface water and within these areas total farm dam storage has been measured by survey. Outside of these areas farm dam volumes are based only on quick assessments of available aerial photo information. Where surface water and groundwater are used together, these estimates seldom differentiate between them. Thus limited land and water management information, particularly for farm dams, irrigation practices and irrigation sources, has restricted these assessments to date. Regularly updated, widespread and consistent land use and farm dam data is needed.

3. Stock and domestic use is not measured but it can account for a significant proportion of the resource use.

Land use and some land management data sets are being used to provide information on water use, pollution risks and as a tool for setting priorities for monitoring programs. There are several land use data sets, collected for purposes other than water resource management, which are of limited use for these applications. Other data sets that are relevant to water resource management cover only some areas of the State.

Current monitoring of management policies and their subsequent impacts, particularly on the community and the State?s economy, is poor. However work is progressing to develop relevant performance indicators for water management plans at various scales. There is a need to increase the level of salinity monitoring, recognising the threat to water resources from dryland salinity. Salt balance and salinity trend estimation requires measurement of salinity at existing and new streamflow and rainfall gauging stations.

Future Directions

There is a strong demand for water to support economic development. The State has sufficient water for our present and future needs, provided that we are careful, flexible and innovative in the use of our water resources and water infrastructure.

The State Water Plan identifies the following future goals:

1. Ensureing continuous improvement in how the water resources are managed in the State. Plans will be reviewed on a regular basis to allow the incorporation of the latest information available and to maintain consistency with the State Water Plan. Ongoing monitoring and evaluation are identified as vital procedures to allow measurement of the change in condition of the resource. The performance of the policies within management plans will be assessed on how they meet catchment and stream health, and economic indicators.

2. The principles of ecologically sustainable development will be adhered to. A precautionary approach to water resources management and use is advocated.

3. Developing further the integrated management approach to water resource management. In the State?s multiple-use catchments it is important to ensure that catchment development, and the consequent use of the water that occurs, is managed in a way that protects the instream, floodplain and estuary users of the catchment. Monitoring stream health will have a high priority.

4. In many areas of the State, water is already fully allocated and further economic development hinges on making greater use of existing resources. This is achieved by encouraging;

· The use of improved irrigation efficiency

· The use of alternative sources of water such as urban stormwater and sewage effluent

The importation of water by pipeline into areas where greater economic benefit can be achieved.

References

Government of South Australia, GSA (1997) Water Resources Act 1997, Government of South Australia.

Government of South Australia, GSA (2000) State Water Plan 2000, Government of South Australia.

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