lower murray alluvium - industry.nsw.gov.au

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Lower Murray AlluviumGroundwater Management Area 016Groundwater Status Report 2010

Publisher

NSW Department of Primary Industries, Office of Water

Level 18, 227 Elizabeth Street GPO Box 3889 Sydney NSW 2001

T 02 8281 7777 F 02 8281 7799

[email protected]

www.water.nsw.gov.au

The NSW Office of Water manages the policy and regulatory frameworks for the state’s surface water and groundwater resources, to provide a secure and sustainable water supply for all users.

It also supports water utilities in the provision of water and sewerage services throughout New South Wales. The Office of Water is a division of the NSW Department of Primary Industries.

Lower Murray Alluvium: Groundwater Management Area 016 – Groundwater Status Report 2010

December 2011

ISBN 978 0 7313 3966 2

This publication may be cited as:

Alamgir, M., (2011), Lower Murray Alluvium: Groundwater Management Area 016– Groundwater Status Report 2010, NSW Office of Water, Sydney

© State of New South Wales through the Department of Trade and Investment, Regional Infrastructure and Services, 2011

This material may be reproduced in whole or in part for educational and non-commercial use, providing the meaning is unchanged and its source, publisher and authorship are clearly and correctly acknowledged.

Disclaimer: While every reasonable effort has been made to ensure that this document is correct at the time of publication, the State of New South Wales, its agents and employees, disclaim any and all liability to any person in respect of anything or the consequences of anything done or omitted to be done in reliance upon the whole or any part of this document.

NOW 11_227


Executive summary

This report is the fifth in a series of status reports on the groundwater resources of the Lower Murray

Alluvial aquifer system, also known as Groundwater Management Area 016 (GWMA016).

The Lower Murray Water Sharing Plan commenced on 1 November 2006 and establishes the rules for the management of the Lower Murray Groundwater Source under the Water Management Act 2000.

The plan is in place for a 10 year period.

The water sharing plan for GWMA016 comprises the deep regional alluvial aquifer systems of the Murray Geological Basin bound by Murray River in the south and the Billabong Creek in the north. The

eastern boundary is shared with the Upper Murray Groundwater Management Area 015 along the Corowa-Urana road. The western boundary is at the confluence of Murray River and the Wakool River, close to the village of Goodnight. The plan does not cover the shallow groundwater resources of

the Shepparton Aquifer.

The current modelled long term average sustainable yield has been set at 83.7 GL in the water sharing plan. The median yearly pumping volume is 73 GL with an average of 80 GL over eight years.

The highest volume of pumping, 135 GL, occurred in 2002-2003 irrigation season and the minimum pumping volume, 54 GL, occurred in 2000-2001.

The groundwater resources of GWMA016 are under stress caused by the pumping of 378 high

capacity production bores which has resulted in a decline in aquifer pressure levels.

Groundwater pressures levels started declining in 1994 with the lowest water levels recorded in 2003. Falling levels threatened the sustainability of the resource, security of supply and water quality. Work

was subsequently undertaken with the local community to reduce the risk of over pumping this valuable groundwater resource.

The implementation of a groundwater sharing plan in 2006 reduced entitlements and thus the volume

of water that can be extracted. Reductions are being phased in over the ten year term of the plan so that irrigators can adjust to the changes. Temporary supplementary water entitlements were issued to some irrigators to allow the reduction in usage to have a triple bottom line outcome. Until the

supplementary water entitlements are extinguished at the end of the plan they will cause added stress such as high seasonal fluctuations in pressure levels at some locations.

Groundwater trading began immediately after the commencement of the water sharing plan. Both

groundwater allocation assignments (temporary trades) and assignment of rights (permanent trades) have been sought after due to the drought. Temporary trades peaked at 33 GL in 2008/09 and permanent trades at 4 GL in 07/08. All applications for trades are assessed by the NSW Office of

Water for third party impacts before any approval is given. Supplementary water entitlements cannot be traded.

Monitoring of pressure levels is occurring in 250 deep observation bores and a portion of these are

fitted with electronic data loggers. Drilling for the enhancement of the observation bore network has seen the completion of 24 new deep piezometers in 2009/10. Instrumentation for telemetry of key monitoring bores was also completed and funding is being sought for further expansion of telemetry.

Groundwater quality is typically highly variable in time and space. Total Dissolved Solids (TDS) range from 140 mg/L to 41,000 mg/L. Monitoring of groundwater quality is ongoing at 20 key monitoring bores. Data has been available for the last six years. Groundwater quality remains almost unchanged

in terms of salinity. There is no definite pattern of improvement or deterioration of groundwater quality with respect to salinity.

i | NSW Office of Water, December 2011


Contents

Executive summary .................................................................................................................................i

1. Introduction.................................................................................................................................... 1

2. Physical setting ............................................................................................................................. 2

2.1 Location and definition of the water source ........................................................................ 2

2.2 Socio-economics................................................................................................................. 3

2.3 Climate ................................................................................................................................ 3

2.4 Physiography and surface drainage ................................................................................... 5

3. Hydrogeology ................................................................................................................................ 7

3.1 Geology............................................................................................................................... 7

3.2 Description of aquifers (water sources) .............................................................................. 8

3.3 Groundwater recharge ...................................................................................................... 12

4. Resource monitoring ................................................................................................................... 13

4.1 Groundwater investigations .............................................................................................. 13

4.2 Groundwater level trends.................................................................................................. 13

4.3 Groundwater flow.............................................................................................................. 23

4.4 Groundwater usage .......................................................................................................... 28

4.4 Water level management .................................................................................................. 29

4.4.1 Local impact management ................................................................................... 30

5. Groundwater quality .................................................................................................................... 36

5.1 Groundwater salinity and chemistry.................................................................................. 36

5.2 Groundwater vulnerability ................................................................................................. 39

5.3 Groundwater Dependent Ecosystem................................................................................ 39

6. Groundwater management ......................................................................................................... 40

6.1 Basis for sharing water ..................................................................................................... 40

6.2 Available water determinations and annual extraction limits ............................................ 40

6.3 Access licenses................................................................................................................. 41

6.4 Water account management............................................................................................. 42

6.5 Works approvals and bore extraction limits ...................................................................... 42

6.6 Groundwater dealings....................................................................................................... 42

8. References .................................................................................................................................. 43

Appendix: Lower Murray Alluvium Shallow Water Source (Shepparton Formation)........................... 44

ii | NSW Office of Water, December 2011


Tables

Table 1 Summer and Winter Average Temperatures in the Water Source ................................... 3

Table 2 Local Impact Trigger Level – Murray Water Sharing Plan.............................................. 31

Table 3 Groundwater Pressure Level Net Change in Monitoring Bores...................................... 32

Table 4 Groundwater Pressure Level Net Change Summary (decline or recovery) ................... 32

Table 5 Water Chemistry ............................................................................................................. 36

Table 6 Bulk Water Provision in the Lower Murray WSP ............................................................ 40

Table 7 Annual Extraction Limits for the Lower Murray Groundwater Source............................. 41

Table 8 Number of Groundwater Bores by Purpose.................................................................... 41

Table 9 Access Licence Dealings ................................................................................................ 43

Table 10 Temporary Trade Statistics (71T) ................................................................................... 43

Table 11 Permanent Trade Statistics (71Q) .................................................................................. 43

Figures

Figure 1 Location Map..................................................................................................................... 2

Figure 2 Annual Average Rainfall ................................................................................................... 4

Figure 3 Average Monthly Rainfall .................................................................................................. 4

Figure 4 Cumulative Difference from Mean Monthly Rainfall (mm) – a Falling Graph

Indicates Dryer than Average Conditions. ........................................................................ 5

Figure 5 Geological Map of Lower Murray Alluvium (GWMA016) .................................................. 7

Figure 6 Schematic Cross Section of the Murray Basin Aquifers (Brown & Stephenson,

1989) ................................................................................................................................. 8

Figure 7 Cross Section of the Lower Murray Alluvium (Plan View) .............................................. 10

Figure 8 Geological Cross Section of the Lower Murray Alluvium (GWMA016)........................... 11

Figure 9 Location of Monitoring Bores .......................................................................................... 15

Figure 10 Groundwater Hydrograph for Monitoring Bore GW036742 ............................................ 16

Figure 11 Groundwater Hydrograph for Monitoring Bore GW036743 ............................................ 16

Figure 12 Groundwater Hydrograph of monitoring bore GW036743/3........................................... 17

Figure 13 Groundwater Hydrograph of monitoring bore GW036744.............................................. 17








iii | NSW Office of Water, December 2011


iv | NSW Office of Water, December 2011




Figure 24 Groundwater Level Contours for the Calivil Formation Aquifer May 2009, Representing End of the Season Maximum Drawdown ................................................. 24

Figure 25 Groundwater Level Contours for the Calivil Formation Aquifer August 2009,

Representing Maximum Recovery before Commencement of the Pumping Season ............................................................................................................................ 25

Figure 26 Groundwater Level Contours for the Renmark Group Aquifer May 2009,

Representing End of the Season Maximum Drawdown. ................................................ 26

Figure 27 Groundwater Level Contours for the Renmark Group Aquifer August 2009, Representing Maximum Recovery before Commencement of the Pumping

Season ............................................................................................................................ 27

Figure 28 Location of Production Bores in GWMA016 ................................................................... 28

Figure 29 Historical Groundwater Usage and Surface Water Allocation (general security). .......... 29

Figure 30 Correlation: Groundwater Usage and Pressure Level Decline Calivil Aquifer................ 30

Figure 31 Correlation: Groundwater Usages and Pressure Level Decline Renmark Aquifer......... 30

Figure 32 Groundwater Pressure Level Depletion/Recovery (Calivil Aquifer) ................................ 33

Figure 33 Groundwater Pressure Level Depletion/Recovery (Calivil Aquifer) ................................ 33

Figure 34 Groundwater Pressure Level Depletion/Recovery Calivil Aquifer .................................. 34

Figure 35 Groundwater Pressure Level Depletion/Recovery (Renmark Aquifer) ........................... 34



Figure 38 Piper Diagram Showing the Average Ionic Composition of GWMA016

Groundwater. The Dominant Ions are Sodium and Chloride.......................................... 37

Figure 39 Salinity Distributions in Calivil Formation Aquifer ........................................................... 38

Figure 40 Salinity Distributions in the Renmark Group Aquifer....................................................... 38

Plates

Plate: 1 Major Canal System in the Groundwater Source Area.................................................... 6

Plate: 2 Groundwater Monitoring Using Advanced Technology .................................................. 14


1. Introduction

This report is the fifth in a series of status reports on the groundwater resources of the Lower Murray

Alluvial aquifer system, Groundwater Management Area (GWMA) 016. Earlier editions were completed in 1986, 1989, 1997 and 1999. This report provides information on the status of groundwater resources in the designated groundwater management area where a water sharing plan

is now under implementation.

The Lower Murray GWMA016 was identified as groundwater system at high risk under a state-wide aquifer evaluation program (DLWC, 1998). Those risks included over-allocation, localised drawdown

and bore interference and salinisation.

The Water Management Act 2000 provides the legal framework for establishing a water sharing plan in GWMA 016, which defines the rules by which the resource is to be managed and shared. It was

developed over four years in consultation with a Groundwater Management Committee. The plan gazetted in 2005 and came into implementation on 1 November 2006.

An extended drought over the past decade and low surface water allocations has placed extra stress

on groundwater pressure levels causing unprecedented depletion.

The objectives of this report are to:

Assess the current status of the groundwater resources in the water source of Lower Murray

Alluvium (GWMA016)

Describe the current groundwater management framework.

The initial chapters of this report provide a general description of the area including the physiographic, social, and climatic setting. Generalised geology, aquifer geometry, recharge and sustainable yield, groundwater quality and groundwater usage are then described. A selection of groundwater

hydrographs, from key monitoring bores, is presented to show the effect of groundwater extraction on groundwater levels.

The current groundwater resource management arrangements, as provided by the water sharing plan,

are then described. This includes information on resource access rules, licensing and groundwater trade.

1 | NSW Office of Water, December 2011


2. Physical setting

2.1 Location and definition of the water source

Groundwater Management Area (GWMA) 016, Lower Murray Alluvium, is located in south western NSW and the eastern part of the Murray Geological Basin, covering 17,900 square kilometres. Its

southern border is formed by the Murray River and the state of Victoria, and in the north by the Billabong Creek. The Corowa - Urana Road defines the eastern border, and the western border occurs at the confluence of the Wakool and Murray Rivers close to village of Goodnight (Figure 1).

The Murray Irrigation Districts, Berriquin, Denimein, Deniboota and Wakool, cover a substantial part of GWMA016.

Lower Murray GWMA016 is underlain by regional shallow and deep aquifer systems which, in places,

provides high yielding and good quality groundwater supplies for irrigation, stock and domestic and town water supply as well as other uses. The management of the water source is regulated by a water sharing plan established under NSW legislation (Water Management Act 2000). The water sharing

plan defines the Lower Murray Groundwater Source as all water contained in the unconsolidated alluvial aquifers of the Calivil and Renmark Formations, and the Shepparton Formation deeper than 12 metres (within the defined area). The Lower Murray deep aquifers extend down to the bedrock to a

maximum depth of 350 metres below the ground surface.

The Calivil and Renmark Formations aquifers are composed of pale grey to white quartz sand layers with lenses of grey to white clay, peat and coal extending from the bottom of the Shepparton

Formation down to the bedrock. The Lower Shepparton Formation has generally yellow to brown poorly sorted sand and clay sediments that extend to a depth of between 20 and 50 metres below the ground surface (further details on the hydrogeology are given in Section 3).

Figure 1 Location Map



2.2 Socio-economics

The larger population centres within GWMA016 are Corowa, Mulwala, Barooga, Tocumwal, Jerilderie, Finley, Deniliquin, Mathoura, Moama, Barham, Moulamein, and Tooleybuc. Irrigated and dryland

agriculture are the main economic activities and includes rice, winter wheat, canola and other cereals, legumes and pasture. There are specialized cattle and sheep farming for prime lamb and beef production including some agro-based industries such as commercial piggeries, feedlots, rice mill and

abattoirs. Most of the area has irrigated agriculture based on channel water sources from the Murray River. The township of Deniliquin has the largest rice mill in the southern hemisphere and the head office of the largest private irrigation company (Murray Irrigation Limited) in Australia.

Significantly below average rainfall and reduced surface water availability over the past decade has created substantial growth in the demand for groundwater. The growth in extraction has caused some stress on the resource, and in some areas significant depletion of groundwater pressure levels has

occurred.

A water sharing plan commenced in November 2006 with a goal of ensuring the sustainable use of groundwater (refer Section 6.1). The lack of surface water supply and the implementation of the water

sharing plan have caused a growth in the construction of new production bores and the development of a vibrant groundwater trading market. The majority of groundwater trades are temporary (seasonal) transfers, although permanent trades have also occurred.

2.3 Climate

The climate of GWMA016 is characterised by very hot summers and cool to cold winters (Table: 1).

Table 1 Summer and Winter Average Temperatures in the Water Source

Deniliquin Corowa

Seasons Months Average Maximum

Average Minimum

Average Maximum

Average Minimum

December 30.6 14.1 31.1 13.6

January 32.5 15.7 31.9 15.6

February 32.0 15.7 31.3 15.7

Summer

Average 31.7 15.2 31.4 15.0

June 15.1 4.5 13.8 3.6

July 14.4 3.4 13.0 2.8

August 16.4 4.4 15.0 3.7

Winter

Average 15.3 4.1 13.9 3.4

The area has relatively low humidity and annual average rainfall of between 400 mm to 500 mm (Figures 2, 3).

Figure 4 shows the pattern of rainfall since 1980. It shows an extended period of below average rainfall between 1995 and 2009, with an acutely dry period from 2005 to 2009. Rainfall for 2010 was above average.



Figure 2 Annual Average Rainfall

Figure 3 Average Monthly Rainfall

Monthly Average Rainfall

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Figure 4 Cumulative Difference from Mean Monthly Rainfall (mm) – a Falling Graph Indicates Dryer than Average Conditions.

Rainfall Residual Difference

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Corowa (74034)

2.4 Physiography and surface drainage

Lower Murray GWMA 016 covers part of the alluvial flood plains of the Murray River system. The area has a complex natural drainage system of rivers and creeks. The country is generally very flat with

occasional variation of low lying sand hills. Vegetation cover is generally thin apart from densely populated river red gum communities along water courses.

The major rivers are the Murray, Edward, Wakool and Niemur which flow through or along the

boundary of the Groundwater Management Area 016 generally from east to west. Billabong Creek flows along the northern boundary. The Bullatale, Tuppal, Box, Meran, Mallan Mallan, Forest, Cockran, Yarran are other streams which flow through the area.

The majority of the surface water supply for the Murray Irrigation Districts is delivered through the 200 km long man made Mulwala Canal (Plate 1), which diverts water from the Murray River at Lake Mulwala. Mulwala canal is the most important artery for supplying water for irrigation, stock, domestic,

industrial, recreational and town water supply in the region.



Plate: 1 Major Canal System in the Groundwater Source Area



3. Hydrogeology

3.1 Geology

Lower Murray GWMA 016 is located within the Murray geological basin which covers an area of over 300,000 square kilometres across south-eastern Australia, extending from the Great Dividing Range

to the east and south, to the coast in South Australia. It is a saucer shaped intracratonic basin flanked with subdued mountain ranges (Brown, 1989) and comprises Cainozoic sediment deposited over three major depositional sequences, which is up to 600 m thick (Brown and Stephenson, 1989). This

basin represents a 55 million year history of marine, freshwater and aeolian (wind-borne) deposits. The basin is filled by a sequence of sediments which commenced deposition in the early Tertiary geological period.

The shallow Shepparton Formation and deeper Calivil Formation and Renmark Group sequences underlie GWMA 016. They were deposited from the early Eocene epoch of the Tertiary period. The Remark Group is the basal formation which sits upon a pre-Cainozoic basement. It was deposited

from the early Eocene to the late Miocene and is virtually continuous over the entire basin (Evans et.al, 1989) The Calivil Formation unconformably overlies the Renmark group and was deposited in the late Miocene to Pliocene. The youngest sequence is the Shepparton Formation which was

deposited between the Pliocene to the Pleistocene of the Quaternary period and conformably overlies the Calivil formation.

Figure 5 Geological Map of Lower Murray Alluvium (GWMA016)



3.2 Description of aquifers (water sources)

The maximum thickness of sediments within the Lower Murray GWMA 016 is about 350 m, around the Moulamein area, west of Wakool. The minimum thickness is found at Corowa where the Murray River

enters the Murray Basin and is around 120 m. Within GWMA 016, the sedimentary sequence had been classified into three main aquifer units based on the deposition period and environment. As described in the previous section, they are:

Renmark Group

Calivil Formation (Pliocene Sands)

Shepparton Formation.

These Formations are illustrated by a schematic cross-section in Figure 6, which shows a slice through the Basin taken from west to east (Brown and Stephenson, 1989).

Although there are three regional aquifers in GWMA016, the Water Sharing Plan (Section 6.1)

demarcates only the Calivil and the Renmark aquifers and terms them ‘deep aquifers’. This Status Report discusses the deep Calivil and Renmark aquifers, with a brief summary on the shallow Shepparton Formation aquifer provided in the Appendix.

Figure 6 Schematic Cross Section of the Murray Basin Aquifers (Brown & Stephenson, 1989)

The Renmark Group aquifer overlies basement rock of siltstone, shale, schist and granite occurring at depths between about 140 m to 350 m below ground surface. It consists of sand and gravel layers up

to 40 m thick inter-bedded with clay layers and lignite. Most clay and silt beds are carbonaceous, with abundant plant remnants, and appear peaty brown in colour. Sandy layers in the formation generally constitute important aquifers where low salinity groundwater is available. Some sand layers in this

formation show favourable aquifer properties which provide high yields. However, in some areas the poorly sorted nature of sands and gravel reduces the transmissivity of these aquifers.




The Calivil Formation (also known as the Pliocene Sand) consists of sand and gravel, inter-bedded with clay layers. It overlies the Renmark Group and occupying depths between 40 m and 140 m below ground surface. The upper surface of this formation slopes to the north-west and its thickness reduces

towards the east (Williams & Woolley, 1992). The Calivil Formation is dominated by sand and gravel beds with individual layers are up to 12m thick, and also consist of poorly sorted quartz cobbles, pebbles, and coarse sand grains in a white Kaolinitic matrix. It is an important source of groundwater

within the Lower Murray GWMA.

The Shepparton Formation is fluvial (deposited by the action of rivers) and is the most shallow and recently deposited of the aquifer formations within GWMA016. It is generally unconfined, containing

the water table, and occurs from the ground surface down to a maximum depth of 70 m. The Shepparton Formation overlies the Calivil Formation and consists of clay and silty clay interbedded with sand layers. The groundwater within the uppermost 25 m of the Shepparton Formation aquifer is

mostly saline, however good quality and high yielding groundwater supplies can be obtained from the highly interconnected coarser sediments associated with ancestral fluvial activity (‘prior streams’). As this report deals with deep groundwater source of the Lower Murray Alluvium (Renmark Group and

Calivil Formation aquifers), further discussion and analysis of the shallow Shepparton Formation aquifer is provided in the Appendix.


Figure 7 Cross Section of the Lower Murray Alluvium (Plan View)



Figure 8 Geological Cross Section of the Lower Murray Alluvium (GWMA016)



3.3 Groundwater recharge

The main recharge sources for the shallow Shepparton aquifers is through direct rainfall infiltration and basal leakage contributed by the Murray River and its anabranches, and irrigation accessions in the

irrigation districts. It is estimated that 10 per cent of the total annual rainfall infiltrates directly into the shallow aquifer.

The deep regional aquifers have very minimal or nil direct recharge from rainfall or basal leakage.

There is virtually no exposure of deep aquifers to direct rainfall in the water source area. A numerical groundwater model developed for GWMA 016 demonstrates that recharge to the Calivil Formation aquifer occurs by downward leakage from the lower Shepparton aquifer. Similarly, the Renmark Group

aquifer is recharged by downward leakage from the Calivil Formation aquifer. In some areas, reverse leakage (upward & downward movement) is observed for both the Calivil and Renmark aquifers.



4. Resource monitoring

4.1 Groundwater investigations

The NSW Government has undertaken technical investigations of the groundwater resources of the Murray valley for several decades. Investigation drilling commenced in 1971 and has continued

intermittently since. Thus far, over 100 bores have been drilled and completed as monitoring bores, in locations shown in Figure 7. Many of the bores are nested with multiple piezometers intersecting different aquifers at different depths. This enables water levels to be measured at different depths, and

assists in understanding the vertical movement of water.

Water levels in most observation bores are monitored quarterly, with the data archived in the NSW Office of Water’s corporate database – GDS (Groundwater Data System). Approximately 30 per cent

of all monitoring bores are also equipped with data loggers that measure groundwater pressure level fluctuations every hour. The data loggers are located at strategic locations to monitor pressure level changes in areas highly impacted by pumping.

Groundwater usage information, coupled with our understanding of the structure and dynamics of the aquifers and water level data allows a sound technical analysis of the groundwater resource and how it responds to extraction. At its most sophistication, this analysis is done using numerical computer

models which estimates the volumes of water moving in, through and out of the aquifers and can forecast what affect any future pumping scenario may have on groundwater levels. A numerical model of Lower Murray GWMA016 has been completed in 2003. A review and reconstruction of the model is

in the process and to be completed by the end of 2011.

4.2 Groundwater level trends

Groundwater pressure levels are routinely monitored by the NSW Office of Water across a network of

observation bores with good coverage over the Lower Murray water source. Monitoring bore locations are shown in Figure 9. The level recording network commenced in 1970s. Hydrographs showing changes to groundwater levels over time for a series of monitoring bores are shown in Figures 10 to

23. A commentary on the level trends observed is provided below.

There was a general rising trend in groundwater pressure level in GWMA016 up until 1994. From 1994, noticeable declines in groundwater pressure level begun to be observed due to the

development of high volume of groundwater pumping. Pressure level decline was generally steady but modest up until 2001. During this period, pressure levels recovered during the non-pumping season to the previous winter level without causing any net depletion from year to year.

In recent years, general groundwater pressure level decline are observed throughout the water source, with only its severity varying across areas.

From around the 2002/03 irrigation season, groundwater pressure levels started declining more

quickly, and recovery began failing to reach previous season’s levels, causing net depletion of the resource. This was due to higher volumes of groundwater extraction as a result of minimal surface water availability and consecutive years of drought.

Maximum pressure level depletion is observed in the Berriquin Irrigation District east of Deniliquin along Moony Swamp Road (Bore GW036742 and GW036743, Figures 10, 11, 12). The area is bounded by Conargo Road in the North and Riverina Highway in the South. The monitoring bores

show constant decline in groundwater pressure levels and do not recover fully during the winter months. In this area, pumping continues through the winter season for dairy operations and the farming of winter pasture.



Groundwater pressure levels are also declining in the area between Murray River in the south and the Riverina Highway in the north (Tuppal Road, Lower River Road), as shown in bore GW036588 (Figures 18). Pumping takes place from both the Calivil Formation and the Renmark Group and

pressure level decline is observed in both aquifers. In the Mooni Swamp Road area north of the Riverina Highway, the maximum drawdown is observed is in the Renmark aquifer (bore GW36743, Figure 12).

In an area between Finley and Tocumwal, pressure levels are declining notably in the Calivil Formation (GW036283, Figure 19). Declines commenced around 1995 and have trended downward since. Periods of decline, where winter recovery has failed to reach previous season’s levels, are

witnessed from 2001 to 2003, and between 2006 and 2009, coinciding with a period of extremely low rainfall and surface water availability.

Groundwater pressure level is also consistently falling in the area West of Deniliquin (bore GW036766,

Figure 21). Both the Calivil and Renmark aquifers show groundwater pressure level depletion. Since 2002, the pressure level has never recovered fully to its previous year winter recovery level.

Steady pressure levels were observed in the areas west of Wakool until 1993, then a slightly declining

trend is observed. During the past few years, large scale groundwater pumping has drawn the pressure level down substantially (bore GW036718, Figure 22).

There is however an area of groundwater level rises to the north east of Berrigan (bore GW036639,

Figure 23).

Groundwater levels were depleting consistently in the water source over last decade because of excessive pumping and low surface water availability. Recent rain (over last two years) in the

catchment area increased availability of surface water, and had substantially reduced groundwater pumping. This has dramatically reversed the groundwater level trend in NOW monitoring bores which are being monitored using advanced technology (Telemetry Plate: 2)

Plate: 2 Groundwater Monitoring Using Advanced Technology

Picture: Brian Woodcraft



Figure 9 Location of Monitoring Bores



Figure 10 Groundwater Hydrograph for Monitoring Bore GW036742

Groundwater Hydrograph of Monitoring Bore No:GW036742Lower Murray Alluvium ( GWMA016)

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Figure 11 Groundwater Hydrograph for Monitoring Bore GW036743

Groundwater Hydrograph of Monitoring Bore GW036743 Pipe 2 Lower Murray Alluvium ( GWMA 016)

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Figure 12 Groundwater Hydrograph of monitoring bore GW036743/3

Groundwater Hydrograph of Monitoring Bore GW036743 Pipe 3 Lower Murray Alluvium ( GWMA 016)

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Figure 13 Groundwater Hydrograph of monitoring bore GW036744

Groundwater Hydrograph of Monitoring Bore No:GW036744 Pipe 2&3 Lower Murray Alluvium GWMA 016

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Groundwater Hydrograph Monitoring Bore No. 36876 Pipe 2

Lower Murray Alluvium GWMA016

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Groundwater Hydrograph Monitoring Bore No:GW036586 Pipe 2, 3 & 4

Lower Murray Alluvium (GWMA 016)

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-91

Feb

-93

Feb

-95

Feb

-97

Feb

-99

Feb

-01

Feb

-03

Feb

-05

Feb

-07

Feb

-09

Time

De

pth

to

Pre

ss

ure

Lev

el (

m) Pipe:2 Calivil

Pipe:3 Renmark

Pipe:4 Renmark

Trendline




Groundwater Hydrograph in GWMA016 Monitoring Bore GW036587

Lower Murray alluvium GWMA016

0

5

10

15

20

25

30

35

01-F

eb-8

8

01-F

eb-9

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4

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eb-9

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Time

Dep

th t

o P

ress

ure

leve

l (m

)

Pipe2: Calivil

Pipe3: Renmark

Pipe4: Renmark

Trendline


Groundwater Pressure Level Hydrograph Monitoring Bore No: GW036585 Pipe No. 2,3 & 4

Lower Murray Alluvium (GWMA016)

0

5

10

15

20

25

30

35

Feb

-86

Feb

-88

Feb

-90

Feb

-92

Feb

-94

Feb

-96

Feb

-98

Feb

-00

Feb

-02

Feb

-04

Feb

-06

Feb

-08

Feb

-10

Time

De

pth

Pre

ssu

re L

eve

l (m

) Pipe: 2 Calivil

Trendline




Groundwater Hydrograph Monitoring Bore No.36588 Pipe 3 & 4


0

5

10

15

20

25

30

35

Feb

-87

Feb

-89

Feb

-91

Feb

-93

Feb

-95

Feb

-97

Feb

-99

Feb

-01

Feb

-03

Feb

-05

Feb

-07

Feb

-09

Time

Dep

th t

o P

res

su

re L

ev

el (

m)

Pipe3: Calivil

Pipe4: Renmark

Trend line


Groundwater Hydrograph Monitoring Bore No.GW036283 Pipe 3 Lower Murray Alluvium (GWMA 016)

0

5

10

15

20

25

30

35Jan-79 Jan-81 Jan-83 Jan-85 Jan-87 Jan-89 Jan-91 Jan-93 Jan-95 Jan-97 Jan-99 Jan-01 Jan-03 Jan-05 Jan-07 Jan-09

Time

De

pth

to

Pre

ss

ure

Le

vel (

m)

Pipe 3: Calivil

Trendline




Groundwater Hydrograph Monitoring Bore No.GW036102 Pipe:1 Calivil


0

1

2

3

4

5

6

7

8

Aug-87 Aug-89 Aug-91 Aug-93 Aug-95 Aug-97 Aug-99 Aug-01 Aug-03 Aug-05 Aug-07 Aug-09

Time

De

pth

to

Pre

ss

ure

Lev

el (

m)

Pipe: 1 Calivil

Trendline


Groundwater Hydrograph Monitoring Bore No:GW036766


0

5

10

15

20

25

30

May

-88

May

-90

May

-92

May

-94

May

-96

May

-98

May

-00

May

-02

May

-04

May

-06

May

-08

May

-10

Time

Dep

th t

o P

ress

ure

Lev

el (

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Pipe1: Calivil Pipe2:Calivil Pipe3: Renmark




Groundwater Hydrograph Monitoring Bore No:GW036718 Pipe 4


0

1

2

3

4

5

6

7

8

9

Sep

-87

Sep

-89

Sep

-91

Sep

-93

Sep

-95

Sep

-97

Sep

-99

Sep

-01

Sep

-03

Sep

-05

Sep

-07

Sep

-09

Time

Dep

th t

o P

ress

ure

Lev

el (

m)

Pipe4:Renmark

Trendline


Groundwater Hydrograph Monitoring Bore GW036639

Lower Murray Alluvium ( GWMA 016)27.5

28

28.5

29

29.5

30

30.5

31

31.5

32

Feb-87 Feb-89 Feb-91 Feb-93 Feb-95 Feb-97 Feb-99 Feb-01 Feb-03 Feb-05 Feb-07

Time

De

pth

to

Pre

ssu

re L

ev

el (

m)

Pipe2

Pipe3

Pipe4

Pressure level rising in all three bores

Trendline




4.3 Groundwater flow

The spatial distribution of groundwater pressure levels are shown in contour maps, Figures 24 to 27. The are two maps for each aquifer (Calivil and Renmark), one showing the configuration of pressure

levels when the aquifer is most stressed (greatest drawdown) at the end of the pumping season (May), and a second when pressures recover to their most full levels before pumping recommences in the new season (August).

The impact in the seasonal level variation in the Calivil Formation is not readily seen in the maps (this is evaluated further in Section 4.3). Both maps show a regional groundwater flow gradient trending northward away from the river Murray and toward the west. Regionally, the groundwater pressure

gradient is very flat, a manifestation of the very flat terrain of the Murray riverine plain. The total fall in head from the high point (south east, 120 m AHD) to low point (far west, 56 m) is only 64 metres over a distance of over 350 km, providing very slow regional flow velocities. Steeper gradients, hence faster

flow rates, are observed around the perimeter of the basement high located in the eastern part of GWMA016 (marked: “Calivil absent”). High volumes of groundwater extraction in the north central part of the area has “captured” some of the west-trending regional flow, reversing flow gradients eastward

toward the area of extraction. The pressure gradient flattens considerably in the central western part of the area.

The pressure contour maps for the Renmark group aquifer are generally similar to those for the Calivil

Formation. A north to westerly regional flow pattern is observed with cones of depression caused by groundwater pumping reversing flow locally. Again, the seasonal pressure level differences are not seen to make a noticeable impact on the regional groundwater flow pattern. Similarly flat pressure

gradients are also observed.


Figure 24 Groundwater Level Contours for the Calivil Formation Aquifer May 2009, Representing End of the Season Maximum Drawdown



Figure 25 Groundwater Level Contours for the Calivil Formation Aquifer August 2009, Representing Maximum Recovery before Commencement of the Pumping Season



Figure 26 Groundwater Level Contours for the Renmark Group Aquifer May 2009, Representing End of the Season Maximum Drawdown.



Figure 27 Groundwater Level Contours for the Renmark Group Aquifer August 2009, Representing Maximum Recovery before Commencement of the Pumping Season



4.4 Groundwater usage

There are currently 378 production or ‘high yield’ licensed bores in GWMA016 (Figure 28). Irrigation bores are concentrated in the Murray Irrigation District. They are most highly concentrated in the Berriquin Irrigation District between townships of Deniliquin and Finley. Groundwater is also used for

stock, domestic, town water supply, recreation, industrial and other purposes throughout, however irrigation accounts for over 95 per cent of all groundwater use. All ‘high yield’ bores are fitted with usage meters.

Surface water is generally used in preference to groundwater due to the lower extraction cost (gravity feed rather than pumping) and lower cost of infrastructure. Within the Murray Irrigation Districts, groundwater pumping was generally low prior to 1995 as surface water availability was high. Many

irrigators had a groundwater licence tied to their surface water licence for security when surface water allocation become low. Some areas however are without a surface water supply and are entirely reliant on groundwater.

The annual volume of groundwater extracted from the 1999-2000 season onwards is shown in Figure 29. The graph also shows the current level of licensed entitlement, and the history of surface water availability represented by the average general security allocation (%).

The average annual volume of groundwater extracted is 87GL/year. The highest extraction in any given year was 133 GL in 2002/03. The pattern of groundwater use across the years is clearly influenced by surface water availability. Close to full surface water allocations in the early 2000s

reduced groundwater extraction to as low as 54 GL/year, with groundwater use rising to over 100 GL/year for three straight years where surface water availability was at or close to zero (2003/04 – 2005/06).

Figure 28 Location of Production Bores in GWMA016



Figure 29 Historical Groundwater Usage and Surface Water Allocation (general security).

4.4 Water level management

As might be expected intuitively, groundwater levels decline when groundwater is extracted at higher

rates, and recover (or rebound) when extraction is reduced. This occurs on a seasonal basis with groundwater levels falling as the irrigation season gets underway, and then recovering when the season ends and groundwater extraction stops. This pattern of cause and effect can also bee seen

year to year, and is best examined by comparing the off-season recovery pressures levels against the previous year’s total volume of extraction (Figures 30 and 31). These graph show what is commonly seen in other large alluvial aquifer systems, where groundwater recovery levels correlate inversely

against pumping volumes. This is seen particularly clearly here from 2005/06 through to 2009/10.



Figure 30 Correlation: Groundwater Usage and Pressure Level Decline Calivil Aquifer

Correlation: Groundwater Usage and Pressure Level Depletion Calivil Aquifer


94

53.3

71.4

131.0

72.0 73.5

58.3

100.5106.3 108.0

86.6

0

5

10

15

20

25

30

1999-2000 2000-2001 2001-2002 2002-2003 2003-2004 2004-2005 2005-2006 2006-2007 2007-2008 2008-2009 2009-2010

Irrigation Year

Dep

th P

ress

ure

leve

l (m

)

0

20

40

60

80

100

120

140

An

nu

al G

W U

sag

e (G

L)

Usage (GL)

GW036587: Calivil Aquifer Winter Recovery Level

Figure 31 Correlation: Groundwater Usages and Pressure Level Decline Renmark Aquifer

Correlation: Groundwater Usage and Pressure Level Depletion Renmark Aquifer


94

53

71 72 73

58

101

106 108

87

131

0

5

10

15

20

25

30

351999-2000 2000-2001 2001-2002 2002-2003 2003-2004 2004-2005 2005-2006 2006-2007 2007-2008 2008-2009 2009-2010

Irrigation Year

De

pth

Pre

ssu

re le

vel

(m

)

0

20

40

60

80

100

120

140

An

nu

al G

W U

sag

e (G

L)

Usage (GL)

GW036587: Renmark Aquifer Winter Recovery

4.4.1 Local impact management

During periods of high groundwater pumping, excessive and undesirable localised water level

drawdown can occur. Section 41 of the Water Sharing Plan for the Lower Murray Groundwater Source makes provisions for local access restrictions when groundwater levels decline to certain trigger levels. Specifically, local access rules may apply if recovery depths exceed the declines listed in

Table 2 in any key NSW Office of Water observation bore.



Table 2 Local Impact Trigger Level – Murray Water Sharing Plan

Year (of the Water Sharing Plan)

Trigger Level (metres decline)

1 5.4 2 6.1 3 6.7 4 7.3 5 7.8 6 8.3 7 8.7 8 9.1 9 9.5

In addition, local access rules may be applied if the average piezometric decline across the water

source exceeds 1.65m over the period of the plan. Local impact management rules do not apply to local water utilities.

Groundwater recovery levels have been analysed to test compliance against those plan rules, as

described in the following.

Currently there is no local impact area management occurring in the Lower Murray Groundwater Source (GWMA016). The trend of groundwater pressure level decline is showing some signs of minor

recovery following drought breaking rains in 2010. The availability of surface water has allowed the demand for groundwater to reduce. Some bores however are showing continuous depletion due to pumping in winter time. In areas east of Deniliquin there are piezometers showing continuous water

level depletion as result of pumping all year round. The following table and figures depict whether the groundwater levels in the deep aquifers, as measured in NSW Office of Water monitoring bores, are either depleting or recovering.

To date the trigger levels cited above have not been breached and local impact management rules have not been enacted. The highest rise in groundwater pressure level occurred in the intensive diary operation area because of significant reduction in groundwater use within 5 km radius of the

monitoring bore. There was a 27 per cent surface water allocation in 2009/10 a significant improvement from the previous three years.

Groundwater pumping reduced from 108 GL in 08/09 to 87 GL in 09/10 (21 GL) which is 25 per cent of

the sustainable yield of this aquifer system. The recent reduction in pumping eased the stress on the aquifer showing recovery in 75 per cent of the monitoring bores in Calivil and 52 per cent in the Renmark aquifer. The Following figures show a graphic presentation of groundwater pressure level

depletion and recovery in the Calivil and Renmark aquifers from 2007 to 2010. Net groundwater pressure level change (Table 3 & 4) has been determined by subtracting the depth to pressure level (August reading) from the pressure level reading of previous year (August). This may show either

decline or recovery from the previous year.

Figure 32-37 is the graphic presentation of pressure level net depletion and recovery. As mentioned earlier the change (depletion or recovery) has been the product of subtracting the groundwater

pressure level from the previous year. Positive change indicates decline and negative change indicates recovery. The data plotted randomly with vertical (positive and negative from zero) scales. Red columns going downwards from zero indicate depletion and green columns going upward indicate

recovery.



Table 3 Groundwater Pressure Level Net Change in Monitoring Bores

Groundwater Pressure Level Net Change in Lower Murray Alluvium (GWMA 016)

Calivil Renmark

GW WORK

NO.

2007-2008 2008-2009 2009-2010 GW WORK

NO.

2007-2008 2008-2009 2009-2010

GW036102 0.63 0.89 0.40 GW036095 0.49 0.55 0.47 GW036351 0.02 -0.11 0.13 GW036486 0.44 -0.81 -0.98 GW036438 -0.12 0.04 -0.07 GW036490 0.26 0.48 0.43 GW036637 -0.50 0.27 -0.04 GW036558 0.26 0.52 0.34 GW036641 -0.16 0.12 0.06 GW036653 0.45 0.61 0.56 GW036766 1.42 0.84 -0.91 GW036682 0.44 0.62 0.55 GW040980 0.80 0.95 0.97 GW036683 -1.06 0.34 -0.02 GW500444 1.56 1.55 -4.41 GW040980 0.95 1.00 0.41 GW036350 0.14 0.21 -0.44 GW088540 -0.39 1.88 -2.25 GW036351 0.16 0.18 -0.38 GW088547 1.70 2.38 -4.40 GW036352 0.14 0.29 -0.41 GW500444 -1.23 2.96 0.19 GW036353 0.80 -0.11 -0.15 GW036350 0.31 0.17 -0.50 GW036354 0.65 0.10 -0.82 GW036351 0.25 0.49 -0.78 GW036355 0.31 0.17 0.86 GW036354 0.30 0.23 -0.81 GW036390 -0.04 0.09 0.07 GW036391 0.16 0.29 -0.21 GW036391 0.12 0.09 -1.26 GW036394 0.07 0.33 -0.15 GW036394 -0.03 0.13 -0.02 GW036589 1.03 1.24 -1.19 GW036584 1.71 1.44 -2.67 GW036635 0.07 0.01 0.03 GW036585 1.24 3.86 -5.41 GW036644 -0.43 1.88 0.02 GW036586 2.10 0.72 -2.47 GW036742 1.92 0.88 -1.20 GW036587 -0.54 5.19 -6.69 GW036743 -2.80 3.91 -6.86 GW036589 1.07 1.15 -1.20 GW036744 3.62 -0.01 -1.53 GW036635 0.96 -0.03 -0.09 GW036747 1.07 0.87 0.48 GW036636 -0.14 0.05 0.05 GW036765 0.70 0.67 -3.72 GW036638 -0.20 0.09 0.03 GW036766 0.92 1.03 0.63 GW036639 -0.56 0.39 0.00 GW036808 0.55 1.72 0.36 GW036643 0.51 -0.26 0.02 GW036871 0.82 0.80 0.05 GW036644 1.16 0.65 -0.18 GW036585 -0.02 0.85 0.34 GW036742 0.86 1.71 -4.59 GW036586 2.68 0.44 -1.83 GW036743 -1.17 3.41 -6.40 GW036638 -0.87 1.46 -2.45 GW036744 1.51 0.64 -2.17 GW036639 -0.47 0.26 0.04 GW036772 0.34 0.98 0.31 GW036765 0.70 0.67 0.51 GW036775 0.44 0.86 0.19 GW036772 0.62 1.56 0.14 GW036871 0.55 0.48 0.05 GW036775 0.47 0.93 0.62 GW036876 2.99 1.89 -4.69 GW036587 -0.53 1.06 0.58 GW040979 1.64 1.02 -1.11 GW036356 0.12 0.51 -0.56 GW036392 0.14 -0.57 -0.43 GW036393 0.03 0.35 -0.05 GW036582 0.74 1.08 -0.38 GW036588 1.65 1.63 -2.32 GW036634 0.02 0.35 0.06 GW036642 -0.48 0.21 -0.12

Table 4 Groundwater Pressure Level Net Change Summary (decline or recovery)

Season Aquifer Max decline Min decline Mean decline Comment

2007/08 Calivil 3.0 -1.2 0.5 Declining

2008/09 Calivil 5.2 -0.6 0.8 Declining

2009/10 Calivil 1.0 -6.7 -1.0 Rising

2007/08 Renmark 3.6 -2.8 0.4 Declining

2008/09 Renmark 3.9 -2.2 0.7 Declining

2009/10 Renmark 0.6 -6.9 0.0 Steady

All values in metres. –ve = rise.



Figure 32 Groundwater Pressure Level Depletion/Recovery (Calivil Aquifer)

Groundwater Pressure Level Depletion/Recovery Calivil Aquifer 2009-2010

-8.00

-7.00

-6.00

-5.00

-4.00

-3.00

-2.00

-1.00

0.00

1.00

2.00

1

Monitoring Bores

De

ple

tio

n/R

eco

very

(m

)

RecoveringDepleting

Maximum depletion: 0.97 mMaximum Recovery: 6.69 m Mean Recovery: 1.04 mMedian: 0.38 m

Figure 33 Groundwater Pressure Level Depletion/Recovery (Calivil Aquifer)


-1.00

0.00

1.00

2.00

3.00

4.00

5.00

6.00Monitoring Bores

Dep

leti

on

/Rec

ove

ry (

m)

Maximum depletion: 5.19 mMaximum Recovery: 0.57 m Mean Depletion: 0.76 mMedian Depletion: 0.47 m

DepletingRecovering



Figure 34 Groundwater Pressure Level Depletion/Recovery Calivil Aquifer


-1.50

-1.00

-0.50

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

Monitoring Bores

Lev

el D

eple

tio

n/

Rec

ove

ry (

m)

Maximum depletion: 2.99 mMaximum Recovery: 1.17 m Mean Depletion: 0.53 mMedian Depletion: 0.34 m

Depleting

Recovering

Figure 35 Groundwater Pressure Level Depletion/Recovery (Renmark Aquifer)

Groundwater Pressure Level Depletion/Recovery Renmark Aquifer 2009-2010

-8.00

-7.00

-6.00

-5.00

-4.00

-3.00

-2.00

-1.00

0.00

1.00


Lev

el D

eple

tio

n/

Rec

ove

ry (

m)

Maximum depletion: 0.63 mMaximum Recovery: 6.86 m Mean Recovery: 0.67 mMedian Recovery: 0.09 m

Depleting

Recovering





-3.00

-2.00

-1.00

0.00

1.00

2.00

3.00

4.00


Le

vel

Dep

leti

on

/ R

eco

ver

y (m

)

Maximum depletion: 3.91 mMaximum Recovery: 2.16m Mean depletion: 0.81 mMedian depletion: 0.67 m

Depleting

Recovering



-4.00

-3.00

-2.00

-1.00

0.00

1.00

2.00

3.00


Lev

el D

ep

leti

on

/ Rec

ove

ry (

m)

Maximum depletion: 3.62 mMaximum Recovery: 2.80m Mean depletion: 0.38 mMedian depletion: 0.41 m

Depleting

Recovering



5. Groundwater quality

5.1 Groundwater salinity and chemistry

The NSW Office of Water has in place a routine groundwater quality monitoring program, and is co-sponsoring a number of studies assessing the chemistry of the groundwater resource of GWMA016. A

broad sampling program was undertaken in 2003 to establish a ‘baseline’ water quality to compare with any future water quality changes. The results are given in Table 5.

Table 5 Water Chemistry

Parameter Units Range Mean Median

Bicarbonates (HCO3) mg/L 33 - 680 241 220

Boron (Soluble) mg/L 0.1 - 0.9 0.2 0.2

Calcium (Soluble) mg/L 6.2 – 1,000 98 34

Carbonate (CO3) mg/L 1.6 - 23 10 10

Chloride (Cl) mg/L 28 – 21,000 2,800 980

Electrical Conductivity S/cm 231 – 53,300 8,300 3,720

Hardness-Total (Calculated) mg/L 47 – 12,000 1,240 300

Magnesium (Soluble) mg/L 6.3 – 2,300 240 53

Oxidised Nitrogen as N mg/L 0.01 - 0.83 0.11 0.02

pH pH Units 7.1 - 8.7 8 8.2

Potassium (Soluble) mg/L 1.6 - 110 20 13

Sodium (Soluble) mg/L 25 - 9000 1,360 610

Sodium Adsorption Ratio - 1.4 - 42 16 13

Sulphate mg/L 0.5 – 3,400 351 115

Total Alkalinity mg/L 27 - 560 204 180

Total Dissolved Solids mg/L 140 – 41,000 5,560 2,200

Groundwater quality is typically highly variable in time and space. Table 5 shows Total Dissolved

Solids (TDS) range from 140 mg/L to 41,000 mg/L. The high mean in relation to the median demonstrates that very high salinities in some samples skew the mean result.

Routine groundwater sampling has continued since 2003. It has generated valuable groundwater

quality data which has been used to better understanding of the hydro-chemical processes in this water source. A recent assessment of the change in EC over a 4-year period in the deep production bores in Murray Irrigation Districts indicates a possible 10% (median) decline in water quality in terms

of salinity.

This work was expanded in 2009/10 with a comprehensive groundwater quality monitoring project funded by the National Water Commission with an objective to determine the risk of deep groundwater

pumping on groundwater quality. The project will complete in 2011.

The chemical composition of groundwater is dependent upon the initial composition of the water during sediment deposition, the duration of the hosting period, the composition of host rock, and the

climate of the area and other depositional environments. Groundwater in GWMA 016 derives its chemical composition through the dissolution of the mineral constituents of the sediments of the Upper Murray Alluvial Aquifer - Dolomite (Ca Mg (CO3) 2), Anhydrite (CaSo4) and Halite (NaCl). The

chemical constituents of these minerals are comparatively more soluble in water than the other major mineral portions of host rocks. The chemical characteristic of the groundwater of GWMA 016 is Sodium-Magnesium-Chloride (Na-Mg-Cl) and Sodium Chloride (NaCl) dominated, as shown in Figure

38.



The major constituents of alluvial aquifers are clastic sediments, composed of silicate minerals such as quartz and feldspars. Halite (NaCl) is mainly responsible for the salinity of water along with other salts such as sulphate. Increased carbonate content gives rise to water hardness.

Figure 38 Piper Diagram Showing the Average Ionic Composition of GWMA016 Groundwater. The Dominant Ions are Sodium and Chloride.

The groundwater quality of GWMA016 is spatially highly variable. The sampling results from 2003

have again been used to prepare maps showing the distribution of groundwater quality for the Calivil Formation and the Renmark Group aquifers (Figures 39 and 40). A specific pattern of spatial variability is difficult to define due to the generally erratic distribution of quality. No vertical quality

profile could be established either because of the high variability. The spatial distribution of EC shows that groundwater salinity is generally higher toward the west.

Under natural conditions, groundwater quality does not change significantly over short time periods

because of the very slow process of chemical dissolution and ionic exchange. However pumping stresses and irrigation can induce quality changes by enhancing the mixing process between adjacent bodies of fresh and saline groundwater. Monitoring and management of groundwater quality is also

undertaken by the NSW Office of Water. The Lower Murray Water Sharing Plan required the establishment of baseline salinity (EC) and Sodium Adsorption Ratio (SAR) values for all the deep production bores before the commencement of the plan. Local management rules may be initiated if

salinity increases exceed a certain threshold.



Figure 39 Salinity Distributions in Calivil Formation Aquifer

Figure 40 Salinity Distributions in the Renmark Group Aquifer



5.2 Groundwater vulnerability

Groundwater vulnerability is a measure of the risk of groundwater to pollution. Generally it is a function of the soil and shallow sediment type, depth to the water table, and the initial quality of the

groundwater. The shallow Shepparton Formation aquifer is generally vulnerable to contamination due high water tables, particularly where there are sandy soils. A monitoring project carried out by the then NSW Department of Land and Water Conservation and its partners found that the risk to

contamination in the Berriquin and Denimein irrigation area is higher than the Cadell and Wakool areas because of the presence of lighter soils.

The deep regional aquifers are less susceptible to contamination by pesticides or any other sources

because of the thick confining clay layers. Groundwater quality status for pesticides or other contamination in the regional deep aquifers is not known.

5.3 Groundwater dependent ecosystem

A study was undertaken ahead of the Lower Murray Water Sharing Plan to identify any groundwater

dependent ecosystem in the Calivil and Renmark aquifers. Although no groundwater dependant ecosystem were identified for those aquifers, it is likely that any micro-invertebrate (stygofauna) present in those aquifers would not be threatened because they are always saturated. There were

areas where vegetation communities are identified as affected by shallow saline groundwater.



6. Groundwater management

The Lower Murray Water Sharing Plan commenced on 1 November 2006 and establishes the rules for

the management of the Lower Murray Groundwater Source under the Water Management Act 2000. The plan is in place for a 10 year period.

6.1 Basis for sharing water

The basis for the water sharing plan is the estimated annual sustainable yield for the Calivil and Renmark aquifers of 83,700 ML/year. This volume is derived from a numerical groundwater model

developed for this water source. The recharge and the provision of environmental water, extraction requirements, share components and extraction limits at the start of the Plan are summarised in

Table 6.

Table 6 Bulk Water Provision in the Lower Murray WSP

Water Sharing Plan Provisions ML/year

Annual average recharge 83,700

Planned environmental water 0

Basic landholder rights 1,525

Native title rights 0

Stock and domestic access rights 0

Local water utility 79

Aquifer access license share components 83,580

Supplementary access license share components 48,480*

Long term average annual extraction limit (LTAAEL) 83,700 (plus supplementary provision, see Table 7)

(*This amount decreases through the life of the plan. Refer below)

6.2 Available water determinations and annual extraction limits

The extraction limit for the Lower Murray groundwater source established at the commencement of the plan was 83,700 ML/ year, plus the volume required for basic landholders right (S&D). A further

provision of 48,480 ML was made for supplementary water access licenses, which will be reduced annually from 2011/12 by the percentages shown in Table 7. Therefore, there will be no groundwater available under supplementary access licence by the 2015/16 water year.

An Available Water Determination (AWD) is made at the beginning of every water year on the 1st of July for aquifer access licenses. The AWD has been 1 ML per unit share every year since the commencement of the plan.

The WSP requires that if the three year average extraction exceeds the extraction limits (as listed in Table 5), then an available water determination for the following year should be reduced by an amount that is assessed as necessary to return total water extraction to the extraction limit. Usage has been

below the extraction limit for the first four years of the plan, thus all annual AWDs have remained at 100 per cent.



Table 7 Annual Extraction Limits for the Lower Murray Groundwater Source

Year of

Plan

Water Year

AWD for Supplementary

Access Licenses

(ML/share)

Extraction Limit

Supplementary Access

Licenses (ML)

AWD for Aquifer Access

Licenses (ML/share)

Extraction Limit

Aquifer Access

Licenses (ML)

Extraction Limit Basic

Land Holder

Right (ML)

Total Extraction Limit (ML)

Total Groundwater Usage (ML)

1 2006/07 1.0 48,480 1.0 83,700 1,525 133,705 101,000

2 2007/08 1.0 48,480 1.0 83,700 1,525 133,705 106,000

3 2008/09 1.0 48,480 1.0 83,700 1,525 133,705 108,000

4 2009/10 1.0 48,480 1.0 83,700 1,525 133,705 87,000

5 2010/11 1.0 48,480 1.0 83,700 1,525 133,705 17,010

6 2011/12 0.8 38,784 1.0 83,700 1,525 114,009

7 2012/13 0.6 29,088

8 2013/14 0.4 19,392

9 2014/15 0.2 9,696

10 2015/16 0.0 0.0

* AWD for Aquifer Access Shares announced 1st July every year.

6.3 Access licenses

There are 376 production bore under 343 Licenses. In some instance, multiple production bores were installed under one approval. Most of the irrigation bores are concentrated in the Murray irrigation district. Highest concentration is in Berriquin irrigation district between township of Deniliquin and

Finley. Table: 8 Showing list of production bores by purpose.

Table 8 Number of Groundwater Bores by Purpose

Purpose No. of Production Bores

Irrigation 206

Irrigation and Industrial 5

Irrigation and Stock 21

Stock Domestic and Irrigation 56

Industrial 30

Recreation 18

Town Water Supply 5

Commercial 1

Research 1

Total 343



6.4 Water account management

Access license water accounts are managed in GWMA016 by rules set out in the WSP, as summarised below.

Account Limit: is the maximum volume of water that can be held in any aquifer access account excluding any transfer. For Lower Murray Alluvium (GWMA016) water source account limit is 300% of which is 3 ML per unit of aquifer share component.

Carryover: This is the maximum amount of water that can be carried over to the next irrigation year. Carryover limit is 200% which is 2 ML per unit of aquifer share component. Zero share access licences local water utility (TWS) has no provision of carry over.

Use limit or take limit: This is the total annual extractable volume of water for the licence. Use Limit must not exceed 150% or 1.5 ML per unit of aquifer access share component plus any transfer traded in or any transfer traded out.

Sequence of debit from an account: where both an aquifer access license and a supplementary water access license are linked to the same water supply works (bores), allocation will be debited from the supplementary water access licence account before being debited from the aquifer access license

account.

6.5 Works approvals and bore extraction limits

Under the water sharing plan, new water supply work (bore) approvals may be granted. After the commencement of the water sharing plan, a substantial number of works approval licences were issued with a ‘zero’ share, or entitlement. Entitlement permitting extraction is obtained by purchasing a

temporary allocation or permanent entitlement from another aquifer access licence. In order to manage localised drawdown impacts, limits are place on the amount of water which may be extracted from any given bore by imposing a bore extraction limit.

The bore extraction limits are determined by hydrogeologists in the NSW Office of Water, who with an understanding of the hydraulic properties of the aquifers, are able to estimate the drawdown effect at any given distance of a certain extraction volume and duration. This is done using an analytical model

known as WIDE. The maximum permitted impact is 10 per cent of the available head above the top of the Calivil Formation aquifer at the nearest bore.

6.6 Groundwater dealings

There are a number of ways groundwater can be trading in GWMA016. Table 9 describes the types of dealings which are permitted under the water sharing plan. Only aquifer access share component of licence are tradable. No supplementary access component can be transferred temporarily or

permanently. Most dealings undergo an assessment by a hydrogeologist of the NSW of Office of Water to ensure unacceptable bore interference does not arise from the transfer.



Table 9 Access Licence Dealings

Section of the Water Management Act

2000

Dealing Type Description

71M Transfer of access licenses Ownership change for access licence

71N Term transfers of entitlements under access licences

Lease of the licence to a third party for a particular term

71P Subdivision and consolidation of access licences

Division of licence in to two or more, or combining of licences

71Q Assignment of rights under access licenses

Simultaneous reduction of a share component on a license and increase by the same amount on another (permanent transfer)

71T Assignment of water allocations between access licenses

Simultaneous reduction of allocation in a license account, and increase by the same amount on another (temporary transfer)

71W Nomination of works under access licence

Nomination of works for extraction purpose on an access licence

Groundwater trading began immediately after the commencement of the water sharing plan on 1 November 2006. Surface water allocation was very low at the time so the trading market begun with the selling and buying of temporary groundwater allocation (71T). Table 10 & 11 shows a summary of

temporary and permanent trading respectively since commencement of the plan.

Table 10 Temporary Trade Statistics (71T)

Irrigation Year No. of Dealings Total Volume Assigned (ML)

2006-2007 36 7,418 2007-2008 160 27,765 2008-2009 222 33,065 2009-2010 212 31,616

Table 11 Permanent Trade Statistics (71Q)

Irrigation Year No. of Dealings Total Units Assigned

2006-2007 1 24 2007-2008 14 4,115 2008-2009 12 3,002 2009-2010 11 1,508

8. References

Evans, W.R., & Kellet, J.R., (1989). Hydrogeology of Murray Basin, South-eastern Australia (BMR Journal of Australian Geology and Geophysics, Volume 11 Number 2/3).

Brown, CM & Stephenson, AE., 1991. Geology of the Murray Basin South-eastern Australia. Australian Government Publishing Service, Canberra.

Kulatunga, N., (1999). Groundwater Resource Status Lower Murray Alluvium GWMA016.

Williams, R.M & Woolley, D. Department of Water Resources -1992. Deniliquin Hydrogeological Map (1:250,000 Scale). Australian Geological Survey Organisation, Canberra, Australia.



Appendix: Lower Murray Alluvium Shallow Water Source (Shepparton Formation) General

The Lower Murray shallow groundwater source is defined as the uppermost part of the Shepparton Formation aquifer (shallower than 12m) within the area defined by Groundwater Management Area 016. It is bounded by the Murray River to the south, Billabong Creek to the north and Corowa in the

east Swan Hill in the west over an area of 17,000 km2.

The main administrative feature of the area is the Murray Irrigation Districts and associated Murray Land and Water Management Plans (LWMPs) that cover about half of the groundwater management

area.

Hydrogeology

The Shepparton Formation represents the most recent (Pliocene to Recent) major phase of fluvial (river) sedimentation. The Shepparton Formation overlies the Calivil Formation and consists of clay

and silty clays interbedded with sand layers. The base of the Shepparton Formation is as great as about 70m deep. The productive aquifers in the Shepparton Formation are usually in the first 20 m of the profile and are often referred to as shallow aquifers. The Lower Shepparton aquifers in some

cases are directly in hydraulic connection with Calivil aquifer below.

Two types of abandoned stream/river channels have been identified in the Shepparton Formation. One type known as prior streams are remnants of older channels, abandoned at some considerable

time in the past (Brown & Stephenson, 1991). The other type ancestral rivers are recently abandoned rivers/streams and often associated with the present river/creek systems. The prior stream sands are up to 20m deep (thickness up to 8m and width up to 100m) and a good source of groundwater (where

salinity is low) for irrigation by shallow bores and spearpoints.

The deposition associated with prior stream systems is the final phase of a long period of fluvial deposition. The prior stream systems can be readily traced from aerial photograph although locating

them in the field is often difficult. Butler (1950) put forward the theory of deposition by prior streams on a regional basis and Pels (1960) mapped prior streams of the southern Riverina in more detail.

Shallow prior stream aquifers are widely developed for irrigation in the Murray Irrigation Districts by

means of spearpoint bore systems. Yields of up to 5 ML/day are obtained from batteries of spearpoints from aquifers which consist of coarse sand layers up to 8m thick. Most of the spearpoints are located in the Berriquin Irrigation District where reasonably good quality groundwater is found.

The groundwater in these prior streams becomes more saline towards the west (higher than 3,000 S/cm), thus restricting groundwater pumping in those areas. Groundwater recharge

The main source of groundwater recharge is from rainfall and irrigation. Infiltration from rivers/creeks and irrigation channels have also been identified as a sources of recharge. The deep Calivil and Renmark aquifers receive water through the shallow aquifer and the lower Shepparton Formation. A

groundwater model was developed in 2001 which conceptualised the aquifer framework with recharge and discharge features. When the water balance for the shallow aquifer was determined, it was essential to identify the usable (less saline) groundwater component for groundwater quantity

management.

The model indicated that the leakage from the Shepparton Formation is the major source of recharge to Calivil and Renmark aquifers and the level of leakage was a function of the level of pumping in



those aquifers. Therefore in order to determine the recharge of the Shepparton aquifer, the model was run to simulate the water balance of all 3 aquifers where extraction from the Calivil and Renmark aquifers were simulated at 83.7ML/year. Shallow groundwater levels

Rising groundwater levels in the shallow aquifer, water logging and subsequent soil salinisation have been a major environment issue in the Murray irrigation districts for over 4 decades. In 1980, the area

of shallow water tables (shallower than 2 m) was about 45,000 ha, with most of the problems occurring in the Wakool Irrigation District. By 1998, the area of shallow watertable expanded to about 55,728 ha (MIL, 1998). The groundwater levels in the irrigation districts are monitored by a network of

about 1,400 piezometers. Shallow groundwater pumping has been promoted to control the shallow water tables including the issuing of “unrestricted use” licence for shallow groundwater pumpers. Over the past decade, an extended severe drought and the implementation of Land and Water

Management Plans have controlled the shallow water tables.

One of the main features of salinity management in the area is the Wakool-Tullakool Sub Surface Drainage Scheme. Watertable levels in the Wakool area are naturally shallow and subsequent

irrigation has exacerbated the problem. The scheme involves pumping shallow saline groundwater to control water tables with strategically placed bores and spearpoints. The scheme commenced in the early eighties and is run by Murray Irrigation Ltd with funding from the state government. Spearpoints and shallow groundwater pumping

The majority of private groundwater pumps within Murray Irrigation Areas are connected to spearpoint style bores that tap the shallow aquifers within 12m of the surface. Most of the spearpoints are located

in the Berriquin and Denimein Irrigation Districts where low salinity groundwater is found in prior stream aquifers. Many of the spearpoint systems were installed during the 1982-83 droughts to supplement low surface water allocations. Many were unlicensed and unregistered fell into neglect

once the drought was over.

Later, recognising that groundwater resource in the region was under-utilised, and the imminent threat of the shallow watertable, landholders were encouraged to extract more groundwater during programs

in the mid 1990’s. In most cases unrestricted access to groundwater was granted (no volumetric entitlement or restrictions). At present there are 311 licensed shallow spearpoints/bores/excavations, which are not managed under the provisions of the GWMA 016 Water Sharing Plan. Volumetric conversion

Deep and shallow aquifers are connected and receive or discharge groundwater from each other. Therefore having unrestricted access to the shallow aquifer compromises the management of both the

shallow and deep aquifers. NSW water management policy also requires all licensed access to be defined by a volumetric entitlement. All shallow groundwater licences issued after 2001 were issued with volumetric entitlements, and the volumetric conversion of non-volumetric licences was completed

in September 2010. Managing access and use

The total groundwater entitlement for the shallow aquifer is 84,660 ML/year, with the main purpose

being irrigation. Groundwater usage has not been comprehensively measured, although some usage has been monitored by Murray Irrigation Ltd (specifically in the Berriquin Irrigation District) for an incentive payment schemes under the land and water management plans.

The shallow groundwater source of GWMA016 is currently managed under the Water Act 1912; however a water sharing plan is scheduled to be introduced in 2011.




An embargo on new licences has been in place since 2004 and was updated on 4 July 2008. It prevents the construction of additional bores to access groundwater within existing entitlements. However, replacement bores are allowed to replace old systems or to relocate existing spearpoints to

obtain less saline water. Stock and domestic bores are still permitted.

The temporary trade of ‘active water’ in GWMA 016 is permitted, subject to an assessment of local groundwater and environmental impacts. Unused entitlement cannot be carried forward to the

following water year, and licensees cannot bring forward or borrow the following year’s entitlement for the current water year.

The stock and domestic demand (basic landholder rights) is around 1.0 GL/year.

Groundwater Entitlements in GWMA016 Shallow

Licence Categories Total Volume (ML/y)

Volumetric licences

Recently converted licences

Aquifer access licences (GL/y) 60.482

Special purpose access licence -(Salt Interception(GL/y)

24.178

Basic land holder light (GL/y) ~1

lower murray alluvium - industry.nsw.gov.au

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