lower darling river catchment...water resources and management overview: lower darling river...

Water resources and management overview

Lower Darling River Catchment

www.water.nsw.gov.au

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.

Water resources and management overview: Lower Darling River Catchment

May 2012

ISBN 978 0 7313 3532 9

This report may be cited as: Green D., Ali A., Petrovic J., Burrell M., Moss P. (2012) Water resources and management overview: Lower Darling River Catchment, NSW Department of Primary Industries, Sydney

Cover photo: Aerial view of the Lower Darling River, May 2010

© State of New South Wales through the NSW Department of Trade and Investment, Regional Infrastructure and Services, 2012

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.

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Water resources and management overview: Lower Darling River catchment

Contents

1 The Lower Darling catchment.................................................................................................... 1

2 Climate.......................................................................................................................................... 4 2.1 Rainfall ................................................................................................................................ 4 2.2 Evaporation ......................................................................................................................... 5

3 Land use....................................................................................................................................... 6

4 Environment ................................................................................................................................ 8 4.1 Native vegetation ................................................................................................................ 8 4.2 Parks and reserves ............................................................................................................. 8 4.3 Wetlands ............................................................................................................................. 9 4.4 Significant biodiversity ...................................................................................................... 10

5 Surface water............................................................................................................................. 11 5.1 The Darling River .............................................................................................................. 11 5.2 Great Darling Anabranch .................................................................................................. 12 5.3 Streamflow characteristics ................................................................................................ 12

6 Groundwater .............................................................................................................................. 15

7 River operations and management ......................................................................................... 17 7.1 Major storages and regulating structures ......................................................................... 17 7.2 Murray-Darling Basin Agreement...................................................................................... 20 7.3 Licensed water use ........................................................................................................... 20

Surface water .................................................................................................................... 20 Groundwater ..................................................................................................................... 21

7.4 Water sharing plans .......................................................................................................... 22 Surface water sharing plans ............................................................................................. 22 Surface and groundwater.................................................................................................. 23 Groundwater plans............................................................................................................ 24

8 References ................................................................................................................................. 26

i | NSW Office of Water, May 2012


ii | NSW Office of Water, May 2012

Tables Table 1: Land use in the Lower Darling catchment............................................................................... 6

Table 2: Threatened aquatic species of the Lower Darling River ....................................................... 10

Table 3: Mean daily flow for selected Lower Darling gauges.............................................................. 12

Table 4 - Menindee Lakes Storage Details ......................................................................................... 17

Table 5: Surface water share components for the Lower Darling catchment 2010–11 ...................... 20

Table 6: Groundwater share components for the Lower Darling catchment 2010-11 ........................ 22

Figures Figure 1: The Menindee Lakes and Lower Darling catchment.............................................................. 2

Figure 2: Topography and elevation of the Lower Darling catchment .................................................. 3

Figure 3: Average annual rainfall in the Lower Darling catchment ....................................................... 4

Figure 4: Mean monthly rainfall at Menindee 1876–2010 ..................................................................... 4

Figure 5: Average annual pan evaporation in the Lower Darling catchment ........................................ 5

Figure 6: Average daily evaporation at Broken Hill 1995–2010............................................................ 5

Figure 7: Land use in the Lower Darling catchment.............................................................................. 7

Figure 8: Annual flow in the Darling River at Weir 32 1959–2010 ...................................................... 13

Figure 9: Hydrograph of daily flows and cumulative deviation from the mean for Weir 32 1958-2011....................................................................................................................... 14

Figure 10: Groundwater aquifers of the Lower Darling catchment ..................................................... 15

Figure 11: Groundwater Management Areas of the Lower Darling catchment.................................. 16

Figure 12: The Menindee Lakes Scheme ........................................................................................... 17


1 The Lower Darling catchment The Darling River is located in the semi-arid environment western New South Wales. The ‘Lower

Darling’ commonly refers to that portion of the Darling River which is regulated by releases from the Menindee Lakes Scheme, near the township of Menindee downstream to its junction with the Murray River at Wentworth, 530 km downstream (Figure 1).

The general topography of the catchment is flat with elevations across most of the floodplain area being less than 100 metres (Figure 2). Land use is dominated by grazing with smaller areas of cropping occurring in the southern half of the catchment and on some of the region’s lake beds.

Prior to construction of the Menindee Lakes Scheme the Lower Darling River was unregulated, and like the unregulated portion of the catchment above Menindee, it was subject to highly variable flow conditions. With completion of the scheme in 1960 the flow regime of the river was altered

significantly, with reduced monthly flow volumes, long periods of constant low flow and reduced frequency of small to medium sized flow events (Green et al. 1998)

A major feature of the Lower Darling is the Great Darling Anabranch and its series of large overflow

lakes. Once filled, the ephemeral lakes of the Anabranch hold water for extended periods of time making the area highly productive and important as waterbird habitat.

Prior to European settlement the Lower Darling was occupied by the Barkindji people. They called the

river the ‘Barka’ and their homelands ranged along the riverine plains from Wentworth up to Wilcannia. The region is rich in Aboriginal heritage, and the river and its lakes remain important cultural sites for the local indigenous population. Today the Lower Darling catchment supports a very sparse rural

population. The main urban centres are Wentworth in the south (population 1,300), Menindee in the north (population 330) and the small village of Pooncarie (population 48) which nestles by the river midway between Menindee and Wentworth.

River red gums along the Great Darling Anabranch

1 | NSW Office of Water, May 2012


Figure 1: The Menindee Lakes and Lower Darling catchment



Figure 2: Topography and elevation of the Lower Darling catchment



2 Climate

2.1 Rainfall The Lower Darling region receives some of the lowest rainfall in NSW. Annual rainfall averages just 220 to 280 mm across most of the catchment with a gradient of increasing rainfall occurring from

north-west to the south-east (Figure 3). At Menindee the rainfall is distributed fairly evenly across the year with monthly rainfall averaging from 16 to 23 mm (Figure 4).

Figure 3: Average annual rainfall in the Lower Darling catchment

Source: Hutchinson and Kesteven 1998

Figure 4: Mean monthly rainfall at Menindee 1876–2010

Source: Bureau of Meteorology Climate Data Online



2.2 Evaporation High summer temperatures result in very high evaporation rates across the Lower Darling catchment. Class A pan evaporation increases from around 1,900 mm in the south-east to 2,100 mm in the north-

west (Figure 5). No stations record evaporation within the catchment. However data for Broken Hill (north-west of Menindee) shows that daily evaporation rates in the north of the catchment are highly seasonal ranging from 2 mm per day in winter up to 13 mm per day in summer (Figure 6).

Figure 5: Average annual pan evaporation in the Lower Darling catchment

Source: Hutchinson and Kesteven 1998

Figure 6: Average daily evaporation at Broken Hill 1995–2010

Source: Bureau of Meteorology Climate Data Online



3 Land use Grazing accounts for over 90 per cent of the land use in the Lower Darling catchment. Small areas of

dryland cropping occur in the southern portion of the catchment and there is some minor irrigation development around Wentworth (Figure 7 and Table 1).

Some of the lake beds in the catchment are used permanently or opportunistically for cropping. Lake

Tandou was previously part of the Menindee Lakes system but has been under permanent cultivation since 1972. Cotton, wheat and barley are grown under rotation with other crops including sorghum, corn, soybeans, sunflowers, chickpeas and canola (Tandou Limited 2007). The lakes of the Great

Darling Anabranch are also subject to cropping when they are dry.

Table 1: Land use in the Lower Darling catchment

Land use category Area (km2) Proportion of area (%)

Grazing 31,608 91.5

Lakes, rivers, dams 1,333 3.9

Native landscapes 652 1.9

Conservation 634 1.8

Forestry 157 0.5

Dryland cropping and horticulture 106 0.3

Wetlands 17 <0.1

Mining 2 <0.1

Residential 13 <0.1

Irrigation 6 <0.1

Source: 2001/02 Land use mapping of Australia, Bureau of Rural Sciences



Figure 7: Land use in the Lower Darling catchment

Source: 2001/02 Land use mapping of Australia, Bureau of Rural Sciences



4 Environment

4.1 Native vegetation The Lower Murray-Darling region of New South Wales retains over 90 per cent of its native vegetation cover (LMDCMA 2008). Four broad vegetation communities are found within the Lower Darling

catchment (as described by Westbrooke et al. 2004).

The Lower Darling River supports extensive areas of riparian vegetation dominated by river red gum woodland on the channel banks and the immediate floodplain, and large areas of black box on the

outer floodplain. Lignum and nitre goosefoot are common understorey species on the floodplain.

On the sandplains and dunefields beyond the river are extensive areas of Belah woodlands, an open semi-arid community dominated by Casuarina pauper. Associated trees include western rosewood,

sugarwood and wilga with an understorey of chenopod shrubs including saltbush, bluebush and copperburrs.

In the western part of the catchment, predominantly along the Great Darling Anabranch, are chenopod

shrublands which are found on the alluvial plains and dry lakebeds. This community is dominated by several species of saltbush and bluebush. Large portions of the alluvial plains along the river and around dry lake margins are covered by shrublands of black bluebush and pearl bluebush, while

bladder saltbush occurs on dry lakebeds and on low-lying areas of the alluvial plain.

East of the Darling River mallee shrublands dominated by multi-stemmed eucalypts grow on sandy rises within the floodplain as well as sandplains and dunefields extending out beyond the river. The

dominant species comprise a mix of white mallee, glossy-leaved red mallee and red mallee which grow to a height of around eight metres.

4.2 Parks and reserves Around 870 km2 of land is conserved within National Parks and Nature Reserves in the Lower Darling catchment. This area is spread over three conservation reserves – Kinchega National Park, Mungo National Park and Nearie Lake Nature Reserve.

Kinchega National Park covers over 440 km2 near Menindee, extending for 62 km along the western side of the Darling River and surrounding Lakes Menindee and Cawndilla. Kinchega is one of only two large conservation areas along the Darling River and includes substantial areas of river red gums, rare

acacia shrublands, and significant examples of bluebush shrubland. The Menindee Lakes are important waterbird habitat with over 30 species of waterfowl having been recorded on Lakes Menindee and Cawndilla, including threatened species such as freckled duck and migratory waders.

The park also has significant Aboriginal and European heritage values. It contains many Aboriginal sites including burials, open sites, carved trees, stone caches and ceremonial sites, as well as many historic structures and relics associated with the old Kinchega pastoral station (NPWS 1999).

Mungo National Park covers over 900 km2 of the world heritage listed Willandra Lakes region in south-west NSW. Around 390 km2 of the park lies within the Lower Darling catchment. The Willandra Lakes are a chain of now dry relic lakes associated with Willandra Creek. The park is of national and

international significance for its landscape, cultural heritage and archaeological values. The lunettes surrounding Lake Mungo, the largest of the lakes, contain evidence of 40,000 years of Aboriginal occupation, fossil remains of Australia’s megafauna and evidence of a reversal of the earth’s magnetic

field (DEC 2006).

Nearie Lake Nature Reserve is approximately 80 km north of Wentworth on the Great Darling Anabranch. The nature reserve is the only conservation area on the Darling Anabranch system. It

covers an area of 43 km2, including 21 km2 of Nearie Lake, the main feature of the reserve. Being one



of the deepest lakes on the Anabranch, Nearie Lake provides an important refuge for waterbirds as other floodwaters in the region dry up. The reserve protects five vegetation communities – the lakebed community, blackbox woodlands, and shrublands of saltbush, bluebush and dillon bush (DECC 2008).

4.3 Wetlands Over 269,000 hectares of wetlands and floodplain woodlands have been identified within the Lower Darling catchment (King and Green 1993). These include lignum swamps, black box woodlands, river

red gum woodlands and lake beds.

The sinuous nature of the Darling River and its anabranch has resulted in the formation of numerous lagoons adjacent to the channel which are typically surrounded by river red gum woodland. They

retain water for up to two years depending on their size and depth. Older, shallower lagoons typically support dense lignum swamps.

The ephemeral lakes of the Great Darling Anabranch provide extensive areas of productive waterbird

habitat. Listed as a nationally important wetland complex in the Directory of Important Wetlands in Australia (DEWHA 2010), the lakes have a combined area of 43,000 hectares and are capable of holding water for up to five years. The lunettes of the Anabranch lakes contain numerous Aboriginal

sites including shell middens, campsites and stone artefacts such as grinding dishes and stones, axe heads, and adzes. Aboriginal burial sites are also present at several of the lakes as are stone arrangements (Lloyd 1992).

Also listed in the Directory of Important Wetlands, the Menindee Lakes system provides semi-permanent aquatic habitat in the region. Despite modification of the hydrology of the lakes, and partly because of it, these wetlands provide valuable waterfowl habitat, particularly as drought refuge when

other lakes are dry. The lakes are also highly valued as a water-based recreational area for the people of western NSW (DEWHA 2010).

Lake Pamamaroo in the Menindee Lakes Scheme



4.4 Significant biodiversity The Lower Darling catchment provides terrestrial, floodplain and aquatic habitat for a range of significant plant and animal species. There are 46 threatened animal species and 14 threatened plant

species within the region that are protected under the NSW Threatened Species Conservation Act 1995. Ten of the threatened plant species are listed as endangered, and include species of saltbush, bluebush, native daisy and acacia.

Of the 27 threatened bird species that use the area the majority inhabit the woodland and sand plain habitats along and beyond the river. Species listed as endangered include the bush stone-curlew, malleefowl, Australian bustard, plains wanderer and regent parrot. Blue-billed duck and freckled duck

are regular visitors to the Darling Anabranch lakes.

The region provides habitat for 13 threatened mammals including critically endangered species such as Gould’s mouse, Mitchell’s hopping mouse, numbat, pig-footed bandicoot and burrowing bettong.

Five species of threatened lizards and one frog species (painted burrowing frog) are also found in the Lower Darling.

There are at least six native fish species known to live in the Lower Darling River, these being western

carp gudgeon, golden perch, bony bream, Murray cod, crimson-spotted rainbow fish and Australian smelt (Green et al. 1998). Six other species that were previously common along the Lower Murray-Darling Rivers are now listed as threatened under the NSW Fisheries Management Act 1994. (Table

2).

The aquatic community of the Lower Darling River is part of the endangered ecological community known as the Aquatic ecological community in the natural drainage system of the lowland catchment

of the Darling River. This includes 21 native fish species and hundreds of native invertebrate species that are found within the Darling River and its associated streams, wetlands and anabranches within New South Wales, including the Lower Darling and Great Darling Anabranch.

Table 2: Threatened aquatic species of the Lower Darling River

Scientific name Common name Status in NSW

Craterocephalus fluviatilis Murray hardyhead Critically endangered

Maccullochella macquariensis Trout cod Endangered

Notopala sublineata River snail Endangered

Bidyanus bidyanus Silver perch Vulnerable

Nannoperca australis Southern pygmy perch Endangered

Mogurnda adspersa Purple spotted gudgeon Endangered

Aquatic ecological community in the natural drainage system of the lowland catchment of the Darling River

Darling River EEC Endangered Ecological Community



5 Surface water

5.1 The Darling River The Lower Darling River flows for 530 km from the Menindee Main Weir to the Murray River near Wentworth. The river has a meandering, complex channel structure with many adjacent wetlands and

in-channel benches (Green et al. 1998).

Downstream of Menindee the river has a well developed floodplain that is 2-4 km wide. Immediately downstream of Menindee several high level effluents leave the river on the western side and on the

eastern side the river is joined by the bottom end of the Talyawalka Creek system (which begins upstream near Wilcannia).

About 100 km south of Menindee the Darling River takes a distinct change in direction, flowing to the

south east. The floodplain increases to up to seven kilometres wide and there are extensive areas of wetlands including lignum swamps, lagoons and shallow floodplain depressions.

At Pooncarie the Darling takes another distinct turn this time flowing to the south-west. The channel

loses the large complex meanders that characterise the previous reaches and the floodplain is much narrower ranging from 1-3 km wide. Many lignum swamps have formed in older shallow billabongs.

About 40 km downstream of Pooncarie the channel of the Darling becomes restricted by underlying

bedrock which is exposed within the channel at Burtundy. The floodplain is less than a kilometre wide, the channel is relatively straight and there are no wetlands or lagoons. Downstream of Burtundy the geologic restrictions are removed and the river returns to its previous meandering nature with a

floodplain up to six kilometres wide and many lagoons adjacent to the channel.

Darling River at Pooncarie Weir



5.2 Great Darling Anabranch The Great Darling Anabranch is the ancestral path of the Darling River. It extends for 460 km, leaving the Darling about 40 km south of Menindee and entering the Murray River downstream of Wentworth.

Moderate to high flows enter the Anabranch from the Darling River, and through Tandou Creek (and then Redbank Creek) which leaves the river downstream of Weir 32 in large floods.

The dominant feature of the Anabranch is a series of large overflow lakes which are located along the

middle reach of the Anabranch. These lakes fill at relatively low levels and numerous small block banks have been built by landholders to prevent annual stock and domestic flows from entering the lakes. Land use along the Darling Anabranch is predominantly sheep grazing however some of the

lake beds are used for commercial cropping when dry.

A pipeline for delivery of stock and domestic water supplies along the Anabranch was completed in 2007. The pipeline significantly increases the efficiency of delivering water supplies along the

Anabranch, with water savings from the project being committed to environmental flows for the Lower Darling through the Living Murray Program. Work is currently underway to remove the many small storages along the channel to restore a more natural habitat and flow regime to the Anabranch.

5.3 Streamflow characteristics The NSW Office of Water maintains a network of 13 stream flow gauges within the Lower Darling

catchment. There are also a number of storage gauges associated with the Menindee Lakes. Table 3 provides mean daily flow for some selected gauges.

The Lower Darling River has been regulated by the Menindee Lakes Scheme since 1960. Some of the

key impacts of this regulation are (Green et al. 1998):

Significant reductions in monthly and annual flow volumes

Changes to the seasonality of flows, with greater flows during mid-summer as a result of

transfers and releases from storage

Reduction in the peak flow for all sized flow events

More persistent low flows

Weir 32 is the first stream gauging station downstream of the Menindee Lakes. Flows have been recorded here since February 1958 just prior to completion of work on the Lakes Scheme. Mean daily

flow is 4,400 ML (Table 3) while the average annual flow is 1,613,000 ML (Figure 8). The highest annual flow was recorded in 1976 (8,760,000 ML) while the lowest was recorded in 2003 with only 31,784 ML.

Table 3: Mean daily flow for selected Lower Darling gauges post Menindee Lakes Scheme

Gauge site Catchment area (km2)

Mean daily flow (ML) Period

Darling River at Weir 32 575,000 4,400 1958-2010

Darling River at Burtundy 647,200 3,316 1960-2011

Darling Anabranch at Wycot n/a 693* 1962-2011

* Extended periods of missing data.



Figure 8: Annual flow in the Darling River at Weir 32 1959–2010

Darling River at Weir 32

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Daily streamflows provide an indication of the variability of flow patterns and the peak height of flood events. Both the frequency and peak height of flood events have been significantly reduced in the Lower Darling since the operation of the Menindee Lakes Scheme as many small and medium sized

events are absorbed by the storages. A plot of daily streamflows in Figure 9 shows that apart from the major floods that occurred during the 1970s the remaining events have peaked in the range of 10,000 to 40,000 ML per day.

In 2010 widespread flooding in the north of the Murray-Darling Basin filled the Menindee Lakes and delivered the first significant flows to the Lower Darling in 12 years. Flows of up to 22,000 ML/d were reached at Weir 32 in December 2010, with a second flood peak of around 38,000 ML/d occurring in

March 2011 after further floodwaters from Queensland entered the system. Releases from Lake

Cawndilla to the Great Anabranch commenced in October 2010 providing the first flows down the

Anabranch in ten years. This provided significant environmental benefits including the filling of some of the

Anabranch Lakes that are listed in the Directory of Important Wetlands in Australia.

The cumulative mass curve in Figure 9 provides insight into long term streamflow trends. The plot is produced by calculating variations from the long-term mean, and can be interpreted according to the

following rules (Burrell and Ribbons 2006):

Where the slope of the curve is rising the flow exceeds the long term average, indicating

wetter periods

Where the slope of the curve is falling the flow is less than the long term average, indicating

generally drier periods

Relative magnitude can be determined by the steepness of the slope and the y-axis of the plot

Figure 9 shows the period of increasing flows associated with the wet period of the 1970s. The period from 1980 to 2000 was one of generally average conditions with short phases of alternating high and

low flow periods. Since 2002 the Lower Darling, like many other inland valleys, has been subject to



severe drought conditions with eight years of significantly below average flows. These low flows can be attributed wholly to drought as the Menindee Lakes dried completely from 2003 until early 2010. The more recent high flows can be seen as a change in the direction of the graph.

Figure 9: Hydrograph of daily flows and cumulative deviation from the mean for Weir 32 1958-2011

date:25/01/12 t im e:11:55:51.78

L ow er D arl ing upstream W ei r 32

19/02/1958 to 31/12/2011

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6 Groundwater Groundwater in the Lower Darling catchment is associated with the Murray Geological Basin, a large

but relatively shallow Cainozoic sedimentary basin, extending over 300,000 km2 of south-eastern Australia. The basin contains sedimentary sequences formed in aeolian, fluvial, and marine environments (Lewis et al. 2008) with marine sediments underlying much of the southern half of the

Lower Darling. This results in high salinity levels across most of the catchment making the water suitable only for stock use.

The floodplain of the Darling River is underlain by a shallow alluvial aquifer (Figure 10). Piezometer

transects indicate that the river loses water to this aquifer (Stannard 1981). The river has a dilution effect on groundwater salinities with salinity values ranging from 400–4,000 milligrams per litre compared to around 20,000 milligrams per litre away from the river (Lewis et al. 2008).

A shallow fluvial aquifer also occurs along the channel of the Great Darling Anabranch. The salinity in this aquifer progressively degrades downstream from less than 1,500 milligrams per litre to over 5,000 milligrams per litre (Brodie 1992).

Figure 10: Groundwater aquifers of the Lower Darling catchment



Groundwater in the Lower Darling catchment is managed according to four Groundwater Management Areas. These are the Lower Darling Alluvium, Western Murray Porous Rock, Kanmantoo Fold Belt and Adelaide Fold Belt Groundwater Management Areas which relate directly to the three major

aquifer systems (alluvial, porous rock and fractured rock) (Figure 11). Water sharing plans are currently in place to cover management of groundwater resources in all of these areas (see Section 7.4).

Figure 11: Groundwater Management Areas of the Lower Darling catchment



7 River operations and management

7.1 Major storages and regulating structures The Menindee Lakes Scheme was completed in 1960 to provide a secure water supply for Broken Hill and to provide water for stock, domestic and irrigation use along the Lower Darling and Great Darling

Anabranch. Prior to the Scheme these large overflow lakes filled only under flood conditions. A pipeline completed in 1952 carries water 120 km from Menindee Lakes to Broken Hill delivering up to 10,000 ML of water a year for domestic and industrial use. Water from the scheme is also used to

meet water requirements along the Murray River in South Australia.

The four major lakes of the storage scheme Wetherell, Pamamaroo, Menindee and Cawndilla have a combined surface area of 457 km2, a storage capacity of 1,730,886 ML and a maximum storage

capacity of 2,050,000 ML at maximum surcharge levels (See Table 4 and Figure 12).

Table 4 - Menindee Lakes Storage Details

Storage Full

Supply Level (m)

Full Supply Capacity

(ML) Lake Wetherell (Including lakes Tandure, Bijijie, Balaka and Malta)

61.67 192,621

Lake Pamamaroo (Including Copi Hollow)

60.45 277,725

Lake Menindee (including Lake Speculation)

59.84 629,488

Lake Cawndilla (including Lake Spectacle, Morten Boolka, Cawndilla Creek & Lake Eurobilli)

59.84 631,052

Combined Menindee 1,730,886

Figure 12: The Menindee Lakes Scheme



Menindee Main Weir is located on the Darling River about 10 kilometres upstream of Menindee. Water stored behind the weir forms Lake Wetherell, and from here water is diverted into the other major lakes of the system. Releases can be made to the Darling River through outlet regulators from lakes

Wetherell, Pamamaroo and Menindee, as well as from the Menindee Main Weir. Lake Cawndilla can only drain to the Darling River while it is connected to Lake Menindee. Otherwise water from Lake Cawndilla may be released to the Great Darling Anabranch via Tandou and Redbank Creeks.

There are three small weirs along the Lower Darling River. Just downstream of Menindee is Weir 32 which was constructed in 1958 to conserve water for the town’s water supply and the Broken Hill pumping station. Pooncarie Weir was constructed in 1968 to provide water supply for the village of

Pooncarie. Burtundy Weir is a privately owned weir built in 1942 (and later raised in 1956) which provides a pumping pool for domestic and irrigation use. A vertical slot fishway installed at Burtundy Weir in 2008 has opened up 234 km of aquatic habitat from Wentworth up to Pooncarie Weir. Plans

are also in place for the construction of fishways at Pooncarie Weir and Weir 32 which will remove all significant barriers to fish movement on the Lower Darling River.

Water has been supplied on an annual basis for stock and domestic use along the Great Darling

Anabranch since completion of the Lakes Scheme in 1960. A series of 17 small weirs were constructed by landholders along the length of the channel for storing this water. These weirs have now been replaced by a pipeline (completed in 2007) which is designed to achieve significant water

savings by reducing transmission losses, evaporation and seepage associated with delivery of the annual replenishment flow. Removal of the many small in-stream structures commenced in 2009 and an environmental flow regime is being developed to restore a more natural flow regime (DECC 2009).

Menindee Main Weir



Interconnecting canal between Lake Menindee and Lake Pamamaroo

The heart of Menindee Lakes Storage - Main Weir, Lake Wetherell (centre, right) and Lake Pamamaroo

(centre, top)



7.2 Murray-Darling Basin Agreement The Menindee Lakes Storage Scheme is managed under the Murray Darling Basin Agreement by the Murray-Darling Basin Authority with the NSW government. The agreement aims to promote and co-

ordinate effective planning and management for the equitable, efficient and sustainable use of the water and other natural resources of the Murray-Darling Basin.

Under the terms of the agreement the water held in Menindee Lakes is to be shared equally between

NSW, Victoria and South Australia. The scheme delivers water to South Australia to meet part of its annual entitlement (around 39 per cent on average) as well as up to 9,000 ML/d to meet monthly storage targets in Lake Victoria (MDBA 2010).

When the total volume of the scheme falls to less than 480,000 ML (equal to 28 per cent capacity) management of the system reverts to NSW to meet the needs of far-west NSW including Broken Hill water supply and the irrigation needs in the Lower Darling. This may also include providing water to

meet the needs of water users and the environment in the NSW Murray Valley. When the total volume of the scheme rises above 640,000 ML (equal to 37 per cent capacity) management of the system reverts to MDBA for the provision of the water requirement needs of NSW, Victoria and South

Australia. When the scheme total volume is between 480,000 and 640,000 ML the current management regime remains until a trigger volume is met. This is known as the 640/480 rule which effectively provides an additional 160,000 ML for drought security.

7.3 Licensed water use

Surface water The Lower Darling River is operated as a regulated system with releases made from the Menindee

Lakes Storage for the environment and water users along the Lower Darling River, and the Murray River in New South Wales, Victoria and South Australia. Water is supplied to the Great Darling Anabranch as an annual stock and domestic flow, however the Anabranch does not form part of the

regulated water supply system.

The majority of water users in the Lower Darling are general security and hold 78,099 ML of annual entitlement (Table 5). The next largest use of water is for town water supply (local water utility licence)

with an annual allocation of 10,135 ML. The majority of this is diverted to meet Broken Hill’s water requirements.

Table 5: Surface water share components for the Lower Darling catchment 2010–11

Access licence category Total share component

Lower Darling Regulated Water Source

Domestic and stock 340.5 ML

Stock only 612 ML

Domestic only 422 ML

Local water utility 10,135 ML

Regulated river (general security) 78,099 unit shares*

Regulated river (high security) 7,633 unit shares*

Supplementary water 250,000 unit shares*

Lower Darling Unregulated Water Source

Domestic and Stock 8.5 ML

Source: NSW Office of Water * In 2010-11 one unit share was equal to 1 ML



Supplementary water access licences allow access to surplus water that was previously termed “off allocation”. The maximum volume that may be extracted over a water year by each supplementary water access licence is set by an available water determination made at the start of each water year.

There is currently one supplementary access licence which may extract up to 250,000 ML per year.

Water licences on the Lower Darling River are managed according to an annual accounting system. Water is credited to the account at the beginning of each year when an available water determination

is made and any water that remains in the accounts at the end of the water year is lost, with the exception of general security accounts which have provisions to carry forward unused water.

More complex rules apply to general security access licences that allow these licence holders to

reduce variations in year-to-year water availability. Water accounts for these licences allow for the extraction of water during periods of declared supplementary access without debit to the general security account whenever the sum of available water determinations during a water year is less than

0.6 ML per unit share. General security licence holders are also allowed to carry over unused water allocations from one year to the next up to a limit of 0.5 ML per unit share plus the volume required to fill on-farm storages that are supplies by works nominated on the access licence (DIPNR 2004).

Limits also apply to the volume that can be credited to general security access licences from available water determinations in the water year. In the Lower Darling, the limit is equal to the greater of 0.5 ML per unit share or 1 ML per unit share minus the volume carried over from the previous water year

(DIPNR 2004).

Water users on unregulated tributaries of the catchment are entitled to extract water with an unregulated access water licence. These licences are subject to a range of access conditions,

including cease-to-pump triggers that protect the health of watercourses. At the time of this report no unregulated access licences existed in the Lower Darling with only 8.5 ML of domestic and stock entitlement within the catchment (Table 5).

Groundwater The groundwater sources in this report refer to those in the Lower Murray Darling and are covered in three water sharing plans being the Murray-Darling Basin Porous Rock Groundwater, Murray-Darling Basin Fractured Rock Groundwater, and the Murray-Darling Unregulated and Alluvial Water Sharing

Plans (see section 7.4). The groundwater sources within these plans that are included within the Lower Murray Darling include the Western Murray Porous Rock, the Kanmantoo Fold Belt MDB, Adelaide Fold Belt MDB and the Lower Darling Alluvial.

Total extractions in the groundwater sources are managed to the long term average annual extraction limit (LTAAEL). A growth in use response will be triggered if average annual usage over a defined period (3 years for all groundwater sources except the Lower Darling Alluvial which is 5 years) in a

water source exceeds the LTAAEL by more than five percent. Growth in use is managed through a reduction (from 100 per cent) in the available water determination for aquifer access licences in the water source. The AWD will be reduced by an amount necessary to return total water extractions to

the LTAAEL (NSW Office of Water 2012B).

In total for the groundwater sources there is 24,716 ML of aquifer entitlement licensed for extraction (majority for irrigation), 5 ML of local water utility entitlement (for town water supply) with an additional

10,700 ML of aquifer entitlement licensed for salinity and water table management throughout the Lower Darling Murray groundwater sources. The AWD for groundwater access licences in all the groundwater sources is 1 ML per unit share, i.e. 100 per cent of entitlement, unless a growth in use

response is required. The carryover of unused aquifer account water varies across groundwater sources with the Kanmantoo Fold Belt MDB and Adelaide Fold Belt MDB allowed to carry over 0.1 ML



per unit share, the Western Murray Porous Rock 0.25 ML per unit share while the Lower Darling Alluvial is not permitted to carryover.

Table 6: Groundwater share components for the Lower Darling catchment 2010-11

Licence Category Share Component

Murray-Darling Basin Porous Rock Groundwater Sharing Plan

Western Murray Porous Rock Groundwater Source

Aquifer access - General 21,624 unit shares*

- Salinity and water Table Management 10,700 unit shares*

Murray-Darling Unregulated and Alluvial Water Sharing Plan

Lower Darling Alluvial Groundwater Source

Aquifer access 876 unit shares*

Murray-Darling Basin Fractured Rock Groundwater Sharing Plan

Kanmantoo Fold Belt MDB

Aquifer 750 unit shares*

Local Water Utility 5 ML

Adelaide Fold Belt MDB

Aquifer 1,466 unit shares*

CATCHMENT TOTAL 35,421

Source: NSW Office of Water * In 2010-11 one unit share was equal to 1 ML

7.4 Water sharing plans A water sharing plan is a legal document prepared under the Water Management Act 2000. It establishes rules for sharing water between the environmental needs of the river or aquifer and water

users, as well as between different types of users. Water sharing plans are designed to provide security for the environment and water users by setting the rules for how water is allocated over a ten year period. In addition the plans set rules for water trading and water allocations.

There is currently one surface water sharing plan that guides water management in the regulated section of the Lower Darling catchment, one water sharing plan covering the unregulated and alluvial groundwater portions and two plans covering the groundwater porous and fractured rock portions of

the Lower Murray Darling. Copies of these plans are available on the NSW Office of Water website www.water.nsw.gov.au

Surface water sharing plans

NSW Murray and Lower Darling Regulated Rivers water sources

The Water Sharing Plan for the New South Wales Murray and Lower Darling Regulated Rivers Water Sources commenced on 1 July 2004 and applies until 30 June 2014. The plan was suspended in 2006

due to severe drought conditions and recommenced on 1 July 2011.

The water in the Murray and Lower Darling is shared between New South Wales, Victoria and South Australia according to the Murray-Darling Basin Agreement and its consequent arrangements. The

Plan only deals with sharing of the water in the Murray and Lower Darling which is within the direct control of NSW. The Plan applies to the regulated portions of the NSW Murray and Lower Darling Rivers. For the Lower Darling this includes the Darling River from the upper limit of the Menindee Main

Weir storage to the upper limit of the Wentworth Weir pool (where it backs up the Darling). It also includes the Menindee Lakes and Tandou Creek. Although the Great Darling Anabranch receives replenishment flows from the Lower Darling it does not form part of the water sharing plan.


http://www.water.nsw.gov.au/


The water sharing plan incorporates a number of environmental flow provisions for the Murray and Lower Darling Rivers (DIPNR 2004):

1. Prevent erosion of water available to the environment as a result of growth in NSW water

extractions. This is achieved by limiting extractions in each water source to those that would result from the rules in the plan and current water use development.

2. Provide water to the Barmah-Millewa Forest and other wetlands and increase the frequency of

high flows during spring and early summer in the Murray. This is achieved by setting aside up to 75,000 ML each year to build up a reserve of water. Releases of water from the reserve are made according to rules that consider flows in the current years and flows over recent years,

and complement rules applied by Victoria.

3. Set aside water for management of blue-green algae in the Lower Darling. This is achieved by maintaining a reserve of 30,000 ML whenever water levels are above those where all water

must be reserved to ensure future NSW extractive water requirements. Water from the reserve can be used when a high blue-green algae level has been declared under the Sunraysia Regional Algal Contingency Strategy.

4. Establish two adaptive environmental water access licences with a total share component of 32,027 units and a protocol developed for management of water credited to these access licences.

Surface and groundwater

Lower Murray-Darling Unregulated and Alluvial water sources

The Water Sharing Plan for the Lower Murray-Darling Unregulated and Alluvial Water Sources

includes the unregulated tributaries and watercourses of the Lower Murray-Darling, as well as the alluvial aquifers that are closely associated with the regulated Lower Darling River. The plan proposes rules for protecting the environment, and for managing water extraction, water accounts and water

trading in the plan area.

For the alluvial water source the plan includes rules on the location of new works and extraction from existing works to protect high-priority groundwater dependent ecosystems, high-priority karst systems

and other environmentally sensitive areas such as rivers or streams (NSW Office of Water 2012C).

In the unregulated water source the plan has put in place rules to maintain a range of stream flows to preserve a healthy river ecosystem including flows that can scour channels, rework sediments, water

floodplains and associated forests; oxygenate water, allow fish passage, maintain stream connectivity and assists species survival. In addition the plan focuses on water management in pools and lagoons as fauna and flora depend heavily on them to provide refuge during the extended periods of low

rainfall and runoff (NSW Office of Water 2012C).

While for unregulated surface water the plan provided for 29 ML for domestic and stock access licences, 2,424 unit shares for unregulated river access licences at its commencement these figure

are no longer representative of volumes at time of preparing this report as much of the unregulated entitlement was either held by Murray licence holders, cancelled following works to pipe water to the Lower Darling Anabranch, or have lapsed as they were no longer required (see Table 5).

At the commencement of the groundwater sharing plan, the plan established a long-term average extraction limit for the alluvial aquifer of 1,529 ML with 748 unit shares of water set aside for aquifer access licences and 42 ML for domestic and stock licences. These figures vary from the licensed

volume at the time of this report due to licences changes since the time the Plan was written (see Table 6).



Groundwater plans

NSW Murray-Darling Basin Porous Rock Water Sources

The Water Sharing Plan for the NSW Murray-Darling Basin Porous Rock Water Sources covers the

groundwater held within the porous rocks of the basin. The Western Murray Porous Groundwater Source underlies the Lower Murray Darling catchment covering an outcrop area of more than 7.3 million hectares. The water source incorporates the Renmark Group (riverine sediments deposited 30-

50 million years ago) and overlying Calivil Formation in the east which grade into the limestones of the Murray Group (marine sediments deposited 12-32 million years ago) and overlying Loxton-Parilla Sands to the southwest. The overlying sand aquifers consists of a layer of sand and gravel that covers

almost all of the Murray Basin, deposited 2-6 million years ago. In the west the unconfined Loxton-Parilla Sands are marine in origin and to the east the coarser sands of the Calivil Formation are derived from rivers and streams that were flowing at the time (NSW Office of Water 2012B).

The plan reserves water for the overall health of the groundwater source and to protect specific ecosystems that depend on groundwater, such as wetlands. This share of water reserved for the environment is also intended to sustain the aquifer system’s aquatic fauna and flora (NSW Office of

Water 2012B).

At the commencement of the plan there were 21,780 unit shares of aquifer entitlement with an additional 14,582 ML of aquifer licences for the specific purpose of salinity and water table

management within the Western Murray Porous Groundwater Source. The plan also sets aside an estimate of 26,765 ML of water for domestic and stock basic rights. Total annual recharge for the groundwater source is estimated at 1,103,965 ML of which 573,479 ML is protected for the

environment. Therefore, the plan establishes a long-term average extraction limit of 530,486 ML.

NSW Murray-Darling Basin Fractured Rock Water Sources

The Water Sharing Plan for the NSW Murray-Darling Basin Fractured Rock Water Sources covers the groundwater held within the fractured rocks of the basin. In this water sharing plan the Kanmantoo Fold Belt MDB and the Adelaide Fold Belt MDB groundwater sources fall within the Lower Murray

Darling catchment.

The Kanmantoo Fold Belt MDB Groundwater Source covers an outcrop area of more than 3.4 million hectares. It is an Early Palaeozoic, orthotectonic orogenic belt containing inliers of strongly deformed

Cambrian Strata. The Adelaide Fold Belt MDB covers an outcrop area of approximately 0.6 million hectares. Its cratonic units consist of strongly deformed and metamorphosed sedimentary and igneous rocks of Palaeoproterozoic age, termed the Willyama Supergroup hosting the famous silver lead and

zinc deposits at Broken Hill. These rocks within the water source accumulated within, or on the edge of, the Proterozoic Australian Craton in continental (including glacial) to shelf marine environments (NSW Office of Water 2012A).

The plan reserves water for the overall health of the groundwater source and to protect specific ecosystems that depend on groundwater, such as wetlands. This share of water reserved for the environment is also intended to sustain the aquifer system’s aquatic fauna and flora (NSW Office of

Water 2012A).

At the commencement of the plan there were 755 unit shares of aquifer access licence entitlement associated with the Kanmantoo Fold Belt MDB Groundwater Source. Total annual recharge for the

groundwater source is estimated at 321,235 ML of which 142,661 ML is protected for the environment. Therefore, the plan establishes a long-term average extraction limit of 178,574 ML.

At the commencement of the plan there were 1,466 unit shares of aquifer access licence entitlement

associated with the Adelaide Fold Belt MDB Groundwater Source. Total annual recharge for the



groundwater source is estimated at 50,487 ML of which 20,195 ML is protected for the environment. Therefore, the plan establishes a long-term average extraction limit of 30,292 ML.



8 References Brodie R. S. 1992, Anabranch Hydrogeological Map (1:250,000 scale). Murray Basin Hydrogeological

Map Series. Canberra, Australian Geological Survey Organisation.

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Department of Environment and Climate Change 2009, Darling Anabranch Project. Accessed online 11/05/2010, http://www.environment.nsw.gov.au/environmentalwater/anabranch.htm

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Hutchinson MF and Kesteven JL 1998, Monthly mean climate surfaces for Australia. Australian National University, December 1998.

Lewis S.J., Roberts J., Brodie R.S., Gow L., Kilgour P., Ransley T., Coram J.E. and Sundaram, B. 2008, Assessment of Groundwater Resources in the Broken Hill Region, Geoscience Australia Professional Opinion 2008/05. Accessed online 11/05/2010, http://www.environment.gov.au/water/publications/environmental/groundwater/broken-hill.html

Lloyd P. 1992, An environmental study of Nearie Lake Nature Reserve and the Great Anabranch of the Darling River - Development of hydrological management guidelines for Nearie Lake Nature Reserve. NSW National Parks & Wildlife Service and Natural Resource Management Strategy of the Murray-Darling Basin Commission.

Lower Murray Darling CMA 2008, Lower Murray Darling CMA Catchment Action Plan 2008. Lower Murray Darling catchment Management Authority, January 2008.

Murray-Darling Basin Authority 2010, Guide to the proposed Basin Plan, Volume 12:Lower Darling Region. Murray-Darling Basin Authority, Canberra.

NSW Office of Water 2010, Water Access Licence Statistics. Accessed online 18/5/2010, http://wma.naturalresources.nsw.gov.au/wma/WALStatisticsSearch.jsp?selectedRegister=WALStatistics

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http://www.environment.nsw.gov.au/parkmanagement/ParkManagementPlans.htm

http://www.environment.nsw.gov.au/environmentalwater/anabranch.htm


http://www.water.nsw.gov.au/Water-Management/Water-sharing/plans_commenced/default.aspx

http://www.water.nsw.gov.au/Water-Management/Water-sharing/plans_commenced/default.aspx

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http://www.tandou.com.au/farm.html