SoE 2003 > Water > 5.2 Surface water extraction

5.2 Surface water extraction

With surface water extraction still unsustainable in parts of NSW, major new systems for better sharing of water have been introduced

NSW is a signatory to the Murray–Darling Basin Agreement which established a limit (cap) on diversions from rivers within the basin to protect and enhance the riverine environment. In recent years, at varying times, a number of inland river valleys have breached the cap. These valleys were the Barwon–Darling, Lachlan, Namoi and Gwydir.

Twenty-six statutory water-sharing plans have been established to govern the future allocation of surface water. These identify an agreed split of water between the environment and consumption over 10 years, and represent a considerable advance in managing river flows.

NSW Indicators

Importance of the issue

The extraction of vast amounts of surface water is placing stress on both river health and the reliability of water supply in NSW. It is now widely recognised that this rate of extraction is not sustainable.

The natural flow patterns of rivers are highly variable. These patterns are essential for maintaining biodiversity and the health of other water-dependent ecosystems, such as wetlands, floodplains and riparian zones. Because flow is one of the key factors determining freshwater ecosystem health and water quality, it is widely used as a measure of aquatic condition. Taking water away and modifying flow patterns can cause fundamental damage to river health.

The natural flows of many NSW river systems have been substantially modified to meet agricultural and urban demands and prevent the flooding of rural and urban settlements. The impacts of modified flows in NSW include:

• degraded water quality
• reduced riverine habitat
• reduced flooding of riparian zones, floodplains and wetlands
• an increase in algal blooms
• erosion of river channels.

These impacts have affected aquatic ecosystems and diversity of habitats and species (see Biodiversity 6.6 and Biodiversity 6.7). Many wetlands in the Murray–Darling Basin have suffered substantial reductions in area because of changes in flow regimes and inundated areas (Kingsford 2000), and many floodplains have turned into terrestrial ecosystems. The National Land and Water Resources Audit (NLWRA) found that hydrologic changes resulting from river regulation and water extraction have a significant impact on river condition (NLWRA 2002b). For more information, see EPA 2000c.

River regulation in NSW

An NLWRA study of NSW river condition found that 87% of the assessed river length in NSW had altered hydrologic regimes (NLWRA 2002b). River systems which have large storages to control flows are known as 'regulated' rivers. Map 5.1 shows the regulated and unregulated sections of NSW rivers.

Map 5.1: Regulated and unregulated sections of NSW rivers

Source: DLWC data, as at 2002

There are also several thousand smaller dams and weirs, constructed by water management authorities and individuals on both regulated and unregulated rivers. These storages hold water for later release to licensed water users, such as towns, industry and irrigators, as well as to meet the basic stock and domestic needs of landholders and native title water requirements. These smaller dams and weirs may also modify river flows and affect aquatic ecosystems (see Biodiversity 6.6).

Water is allocated in NSW through a licensing system managed by the Department of Infrastructure, Planning and Natural Resources (DIPNR). Table 5.1 presents a breakdown of the licensed entitlement to water for irrigation and other uses in NSW by valley. The figures show that 96% of water entitlements for regulated and unregulated streams in NSW go to irrigation farming.

Table 5.1: Licensed entitlement of surface water in NSW by valley for irrigation and other uses, 2002

Source: DLWC data, as at 2002

Water use in NSW

The NLWRA assessed water use in Australia between 1983–84 and 1996–97 (NLWRA 2001b). It found that surface water use in NSW rose by 52% over the period from 5932 gigalitres (GL) to 9000 GL. This was the largest increase in any Australian State or Territory. Most of the increase was for irrigation, which rose by 76% from 4910 GL in 1983–84 to 8643 GL in 1996–97 (including the use of ground water).

Table 5.2 shows the amount of surface water used by economic sector in NSW in 1996–97, the last year for which data is available.

Table 5.2: Mean annual surface water use in NSW, 1996–97

Source: NLWRA 2001b

As Table 5.2 shows, irrigation accounted for 90% of the surface water used in NSW in 1996–97. Approximately 45% of Australia's total irrigated area was in NSW, which also used more water than any other State, about 40% of the national total. Water extraction limits are now being approached or have been exceeded in most of NSW, including in all of the catchments of the Murray–Darling Basin (NLWRA 2001b). In 1996–97, entitlements to water exceeded its use by nearly 25%. Full use of entitlements would bring an even greater impact on already stressed systems, although the policy is to restrict supplies where entitlements are higher than the capacity of the resource.

The total volume of surface water used in coastal regions is substantially lower than in inland areas, although water quality requirements are higher because the use is predominantly urban. With the growing population and urban development along the coast (see Human Settlement 2.1), increasing and maintaining sources of high-quality water for potable use has become a major priority for these areas.

In inland catchments, surface water use is mainly influenced by seasonal irrigation demand and availability of water. In dry years when less water is available, use may be relatively high. The reverse may occur in years when water is abundant.

Although urban water use is a small amount of the total use in NSW, it can have a significant impact when taken from relatively small streams. The use of treated effluent and stormwater for non-potable uses and environmental flows can assist in reducing pressure on water resources in urban areas (see Human Settlement 2.2).

In some rivers water may be used more than once. For example, nearly all of the water discharged from the major dams (other than spills) passes via a power station. Water that is returned to its source, however, may have a different temperature or chemical composition, or contain elevated pollutant levels (see Water 5.3 and EPA 2000c).

Murray–Darling Basin Ministerial Council cap

Following an assessment by the Murray–Darling Basin Ministerial Council (MDBMC) in 1994, it became evident that the level of diversions from rivers in the basin had become unsustainable. In 1995 the MDBMC introduced a limit or 'cap' on extractions throughout the basin. This restricts extraction to the amount of water taken in 1994, but allows for variations depending on seasonal and water inflow factors. In August 2000, the MDBMC reviewed the cap and agreed to maintain it. It also extended an existing embargo on issuing new licences for regulated streams to cover all unregulated streams over the NSW area of the Murray–Darling Basin.

Table 5.3 shows the performance of NSW catchments against the cap for the three years up till 2001–02. It also indicates where flow rules have been implemented.

Table 5.3: NSW exceedances of the Murray–Darling Basin Ministerial Council cap from 1999–2000 to 2001–02

Source: DLWC data, as at 2003

Notes: ^(a) Figures for this year not available. Cap exceedance based on past performance and activity in the valley during the season.

^(b) From 2001–02, the Lower Darling was combined with the Barwon–Darling (Upper Darling) for assessing cap exceedence.

^(c) Cap exceeded in the Barwon–Darling (Upper Darling) but the combined Upper and Lower Darling was below.

^(d) Performance cannot be assessed because the cap has not been finalised for the Border Rivers valley.

In 1999–2000, the Barwon–Darling (Upper Darling only) exceeded the cap. The following year it was exceeded in the Lachlan, Namoi–Peel and Barwon–Darling (Upper Darling only), while in 2001–02, the Lachlan and Gwydir valleys breached the cap.

The exceedences of the cap show that some inland NSW rivers are under significant extraction pressure, especially those that supply water to extensive irrigation areas (see also EPA 2000b for 1998–99 exceedences). For more information on the cap, see EPA 2000b; MDBC 1999; MDBC 2001; MDBC 2002; and MDBC 2003.

Response to the issue

It is widely recognised that water is a finite resource and too much is being extracted in NSW. The major responses to the unsustainable use of surface water have been to:

• quantify available supplies and develop mechanisms to allocate water for the environment and other uses
• increase the efficiency of water use to achieve more with the water available.

There has been a major program of water reform in NSW since 1995 under the framework of the Council of Australian Governments and more recently the NSW Water Management Act 2000. One of the key outcomes has been the introduction of water-sharing plans. New programs are working to return flows to rivers, better manage the flows for improved environmental outcomes, and introduce a range of programs to promote more efficient water use.

Water sharing

A key element of the NSW water reform process was the introduction of the Water Management Act 2000. The Act gives clear directions on how water is to be shared between users and the environment and provides a legislative basis for the setting up of water management plans and committees. A primary objective is to improve the health of the State's waters with the protection of water sources and their dependent ecosystems receiving first priority in water-sharing plans.

The plans have a statutory basis and are in force for 10 years, with a review after five years. They will provide a period of security both for water users and in meeting environmental needs. Thirty-five water-sharing plans had been introduced by March 2003, covering regulated and unregulated surface water sources, as well as ground water. Twenty-six of these are for surface water sources only. The interim environmental flow objectives established in 1999 form the basis for the environmental water provisions in water-sharing plans (see EPA 2000f).

Restoration programs

Since construction of the Jindabyne Dam as part of the Snowy Mountains Hydro-electric Scheme in the 1960s, less than 1% of the natural average annual flow has been released to the Snowy River downstream of Jindabyne. In August 2002, the NSW and Victorian Governments agreed to increase this to 22% within 10 years. The first release of water has been to the Mowamba River, which accounts for approximately 6% of the natural average annual flow in the Snowy River downstream of Jindabyne. Flow will also be restored to a number of other streams affected by the Snowy Mountains Scheme over the 10-year period, including the upper Murray, Murrumbidgee, Goodradigbee and Geehi rivers.

The ultimate goal of the program is to restore 28% of the Snowy's natural flows. The environmental flows arrangements also include a commitment to provide 70 GL of water each year to the Murray River through greater efficiencies of water use.

Restoring the flow of the Snowy River is part of an agreement between NSW, Victoria and the Commonwealth to corporatise the Snowy Mountains Scheme. The NSW and Victorian Governments have committed $300 million to achieve the water savings necessary to ensure that the reduced diversions from the Snowy will not affect water users.

Another restoration program has been initiated for the Murray River. In April 2002, the Murray–Darling Basin Commission agreed to a comprehensive community engagement strategy to address the issue of environmental flows in the river, including an analysis of the economic, social and environmental impacts of restoring them. As a large amount of water will be needed for the flows to significantly improve the health of the Murray, there will need to be adjustment over many years. Community consultation and scientific analysis is under way into what should be the target level of flow to be returned to the river. Three environmental flow volumes have been proposed: 350 GL per year, 750 GL per year or 1500 GL per year.

The MDBMC also announced a range of structural and operational changes and investigations to make the best use of water currently available to the River Murray environment. These measures will cost $157 million over seven years and complement other work already in train, including the development of fish passages and salt interception works, and measures to improve wetland health.

In addition, the NSW Weirs Policy aims to halt and, where possible, reduce and remediate the environmental impact of weirs.

Efficiency of water use

Several assistance schemes are in place to promote efficient water use by irrigators. Land and water management plan (LWMP) areas have State Government funding of $112 million, plus substantial contributions from irrigators, to provide financial incentives to improve the sustainable use of water. LWMP areas include the Murray and Western Murray, Coleambally, Murrumbidgee and Jemalong. Further assistance is provided to irrigators outside these areas through the Irrigated Agriculture Water Use Efficiency Incentive Scheme. In 1998, the NSW Government allocated $25 million to this five-year scheme to plan, adopt and monitor best-management irrigation practices and water-efficient technologies.

The Water Reform Structural Adjustment Program provides extension, education services and financial assistance to the NSW irrigated agricultural sector. The program has two specific initiatives on water use efficiency:

• WaterWise on the Farm, which aims to improve the capacity of irrigated farm managers to adjust to water reforms primarily through the adoption of best-management irrigation practices and technologies
• the NSW Agriculture Water Use Efficiency Unit, which provides information and advice to irrigators and government on efficient water use, water access and licensing.

The NSW Water Conservation Strategy (DLWC 2000b) also promotes integrated water-cycle management in NSW, including improving water efficiency in the industrial, commercial and agricultural sectors.

Monitoring

The Integrated Monitoring of Environmental Flows (IMEF) program examines the effects of environmental flow strategies on the hydrology, morphology and ecology of regulated rivers and associated wetlands. The program is expected to be very useful during the mid-term review of water-sharing plans (Chessman & Jones 2001).

Effectiveness of responses

With the recognition that too much surface water is being extracted, new systems have been developed to govern the allocation of water. While it will take several years to accurately assess the impact of environmental flow provisions in NSW, some excellent responses have been observed from the IMEF program. For example, bird breeding in wetland areas has been a success following additional flows in the Murrumbidgee, Lachlan, Gwydir and Macquarie river basins. There has also been evidence of the effectiveness of using flushing flows to disrupt the growth of blue-green algae (DLWC 2001d).

The impact of water-sharing plans is also expected to be positive. For example, modelling of the plan in the Namoi which commenced in July 2003 predicts it will achieve a 75% recovery in the natural frequency of flooding in the mid-catchment wetlands.

Results to date suggest that environmental flows are beneficial to the environmental health of aquatic ecosystems. The IMEF program, as well as monitoring and reporting against the performance indicators specified in water-sharing plans, will help to assess the impacts of the environmental flow rules and water-sharing arrangements in the future.

While significant efforts have been made to improve the efficiency of water use in the agricultural sector, there is still more potential for efficiency gains (NLWRA 2001a). For example, it is estimated that only 77% of diverted water reaches users. This could be significantly improved through more efficient methods of application.

Future directions

Agriculture, industry and government all need to find ways to achieve a more efficient use of water. Water efficiency will be the source of future gains over the next 10 years.

Increased efficiencies and the restoration of flows through the implementation of water-sharing plans will be essential elements to ensuring sustainable levels of surface water extraction into the future.

Several assistance schemes are in place for agricultural industries to promote efficient water use by irrigators. Human Settlement 2.2 outlines water-efficiency measures for urban areas.

In addition, more transparent regulation supported by reliable metering is needed for all significant water uses to measure progress in water efficiency. Metering has largely been achieved in urban areas, but in the agricultural sector, recording, billing and reporting of water use needs to be made more transparent.

In areas subject to significant demand for rural-residential and/or hobby farm development, the potential increase in river extraction needs to be considered when making decisions about permitting riparian subdivision.

Linked issues

2.1 Population and settlement patterns

2.2 Urban water

4.1 Land-use changes

5.1 Freshwater riverine ecosystem health

5.3 Surface water quality

5.4 Groundwater extraction

6.6 Aquatic ecosystems

6.7 Aquatic species diversity