Management of Menindee Lakes 2011-2012 – Issue 8. 20 April 2012

Content

The flood peak in the Darling River is currently entering the Menindee Lakes. Inflows of 64,000 megalitres per day (ML/d) have been recently calculated and inflows of over 50,000 ML/d day are expected to continue over the weekend before beginning to fall. Airspace in the lakes is being used to minimise the flood impact around the  Menindee township and downstream. Upstream at Wilcannia the river is falling slowly and no further rises are anticipated for this event.

This paper, and updates to follow, describes current flow conditions and operations, as well as information on what
can be expected through April and May as the flood waters pass through the Darling River system.
Residents and authorities are reminded to check with the NSW Office of Water in Buronga on the required
approvals before undertaking any earthworks to protect infrastructure or crops.
 

Management of Menindee Lakes 2011-2012 Issue 7 – 5 April 2012

Content

Introduction
The flood peak in the Darling River is now approaching Wilcannia. Upstream at Tilpa the river level is falling and no
further rises are anticipated in this event. Downstream at Menindee, high inflows to the lakes system are expected
throughout April and into May, however, maximum outflows will be limited to current levels. The NSW Office of
Water and State Water Corporation are continuing to manage operations at Menindee Lakes in anticipation of the
forecast inflows.
This information paper updates current flow conditions and operations, as well as provides information on what can
be expected through April and May as the flood waters pass through the Darling River system.
In short, residents along the Darling River, from downstream of Tilpa to Burtundy, can expect an extended period of
high flow and widespread rural inundation, similar to events of 1971, 1990 and 1998.
Residents and authorities are reminded to check with the NSW Office of Water in Buronga, approvals that
might be necessary before undertaking any earthworks to protect infrastructure or crops.

River Operations
Darling River Flows and Menindee Storage Volume
The flow in the Darling River main channel at Wilcannia is currently at 39,000 megalitres per day and the flow in the
Talyawalka Creek is over 50,000 megalitres per day. This combined flow is expected to approach a maximum of
about 100,000 megalitres per day over the next few days causing major flooding. This is slightly lower than the
early forecasts but comfortably within the range of planning expectations.
Downstream at Menindee, releases from the lakes system have been made in preparation of the anticipated
significant inflows. The lakes are currently 82 percent full and can hold a further 600,000 megalitres under
surcharge conditions. A large proportion of this available airspace will be used to manage forecast inflows of
between 60,000 and 70,000 megalitres per day during April.
The main weir gate has been re-positioned in the water to limit outflows (measured at Weir 32) to a maximum of
35,000 megalitres per day, making town flooding and conditions immediately downstream of Menindee no more
severe than what is currently being experienced. This will also cause lake levels to rise throughout April and May.
The NSW Office of Water will aim to begin reducing outflows from the lakes as soon as possible to allow water
levels to fall and alleviate flooding in the Menindee town area and downstream. However this is not expected until
May. Minimising outflows will also ensure that the lakes are full at the end of this flood event to provide maximum
resource availability into the future.
Lower Darling River Flows
Downstream flooding could be similar to that experienced during the 1998 flood which had a comparable peak flow
at Bourke of 230,000 megalitres per day (13.78m gauge height). Menindee releases to the Lower Darling in that
event reached 46,500 ML per day through Weir 32 (7.45m gauge height or 10.0m at the Menindee Town gauge).
The targeted peak flow for this 2012 event is 35,000 megalitres per day through Weir 32 and with flows from the
Talyawalka, combined flows in the Lower Darling immediately downstream of the Menindee Lakes will be as high
as 50,000 megalitres per day. Historically, flows of this size, generally flow evenly to the Lower Darling and the
Great Anabranch.
As far as possible the NSW Office of Water will reduce lake outflows at the time of peak Talyawalka inflows below
Weir 32 to minimise the influence of the Talyawalka on the Lower Darling. If that can be achieved then a flow pulse
of 22,000 - 24,000 megalitres per day in the Lower Darling will not be experienced but rather steady flow conditions
of around 18,000 to 20,000 megalitres per day produced by the Menindee outflows for the past few weeks, will be
seen.
Water levels in the Lower Darling River at Pooncarie and Burtundy are both rising very slowly. The NSW Office of
Water will aim to keep peak flow in the Lower Darling below that of the 1998 event, and no more than about 24,000
ML per day (7.7m gauge height) at Pooncarie and 22,000 ML per day (7.7m gauge height) at Burtundy.
Great Darling Anabranch Flows
Flow in the Lower Darling at the Great Anabranch effluent has been relatively steady throughout March at around
18,000 megalitres per day, commensurate with the steady flows through Weir 32. In the Anabranch at Wycot the
flow gradually rose through March to reach 13,000 megalitres per day and some 4.2 metres. At the peak of flow,
expected in late April/May, levels are not expected to exceed 5.2 metres. A few thousand megalitres per day is now
flowing in the lower reaches of the Anabranch and joining the Murray River. It is anticipated that this full
connectivity through the Anabranch system will last at least through May, with significant flow volumes expected to
reach the Murray River.
Combined Murray and Murrumbidgee River Flows
The flood peak in the Murrumbidgee River is current downstream of Hay where the river is now falling from 12.9
metres. Peak flow of around 40,000 megalitres per day is expected at Balranald next week. This water will then
enter the Murray River and produce flows at Euston Weir of up to 60,000 megalitres per day from mid April.
It is expected that the Murray peak flow will pass Wentworth in mid to late April with the Darling River contributing
steadily flows of around 18,000 to 22,000 megalitres per day during this period. Flows from the Great Darling
Anabranch will be much longer in arriving at the Murray and have minimal impact on peak flows.
It is expected that high flows to South Australia will persist from mid-late April to early

Community Information Sheet: Issue 9 Management of Menindee Lakes 2011-2012

Abstract or description: 

After almost three months travel time, the flood peak in the Darling River has arrived at the Menindee Lakes.Inflows of nearly 60,000 megalitres per day were experienced during the third week of April, but are now falling and have now reduced below 40,000 megalitres per day. Airspace in the lakes minimised the flood impact around Menindee township and downstream. Upstream at Wilcannia, the river is falling steadily and no further rises are anticipated from this event.

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Information Paper Menindee Lakes water saving opportunities: April 2012

Content

The Menindee Lakes water storage scheme is a complex system in far-west New South Wales. The scheme was built for water storage, and whilst this is still its primary purpose, it is now managed as a multi-purpose resource.
The Menindee Lakes also has high environmental and cultural values and is a focus for tourism and recreation in far-west of the State.

Not only is the management of the lakes complex in its own right, but it is also part of the equally complex water sharing arrangements of the Murray-Darling Basin Agreement.
Everyone who has ever heard of the Menindee Lakes seems to have an opinion as to how the lakes should be managed and typically, the opinions expressed reflect particular interests and perspectives.
The purpose of this paper is to give a brief overview of the Menindee Lakes, how they are currently managed, and how management and operations need to consider a complexity of issues.
Importantly, the paper outlines the reasons the NSW Government does not support the changed operations of the lakes proposed by the Commonwealth Government, that was recently the subject of a Memorandum of Understanding between the Commonwealth and NSW Governments.
The Menindee Lakes storage scheme
The Menindee Lakes storage is a series of nine natural lakes, part of the Travellers Lake System adjacent to the Darling River in far-west NSW.
In the early 1950s and 1960s, the NSW Government constructed the Menindee Lakes water storage scheme by connecting the natural lakes and Darling River by a series of weirs, regulators, inter-connecting channels and levees.
When full, the storage scheme has a surface area of 453 square kilometres and stores 1,731,000 megalitres at full supply level.
It is also one of only two storage systems in inland NSW that can be surcharged during floods, although levels must be reduced to full supply level as soon as possible after the peak of the flood has passed.
The initial purpose of the storage scheme was to secure water supply for Broken Hill and to foster economic development in far-west NSW through irrigation. The lakes have subsequently been used to supply water to Victoria and South Australia under the Murray-Darling Basin Agreement.
The Menindee Lakes scheme is owned and maintained by the NSW Government.
Each year the Murray-Darling Basin Authority pays NSW $320,000 and three-quarters of the costs of operations and maintenance.

Management of Menindee Lakes 2011-2012 Issue 6 – 23 March 2012

Abstract or description: 

High flows generated from major floods in northern NSW and southern Queensland catchments during January
have merged and around 4,400 gigalitres has passed through Bourke so far in this event. The peak reached Tilpa
this week with the Darling River rising to a peak of 12.9 meters and a flow of 130,000 megalitres per day. Peak
flows are expected to reach Wilcannia in about 10 to 12 days time and arrive at Menindee in mid-April. The NSW
Office of Water and State Water Corporation are continuing to manage operations at Menindee Lakes in
anticipation of the forecast inflows.

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Community Information Sheet: Issue 4 Management of Menindee Lakes 2011-2012

Abstract or description: 

Management of Menindee Lakes
Issue 4 – 24 February 2012

 

Major flood flows were generated from northern NSW and southern Queensland catchments during January and are making their way into the Darling River. The NSW Office of Water and State Water Corporation are continuing to manage flood operations at Menindee Lakes in anticipation of the impending substantial inflows. Two significant flood peaks are approaching Bourke; from the east (Barwon River) and from the north Culgoa/Bokhara River systems). They are forecast to merge during the first week of March, with the Barwon River flows expected to arrive slightly earlier than those from the Queensland Rivers. The scale of this event at Bourke and downstream is expected to be at least the peak level of 13.

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Management of Menindee Lakes 2011-2012 Issue 3 – 10 February 2012

Abstract or description: 

Heavy rainfall and flooding in northern NSW and Queensland has triggered pre-releases from the Menindee Lakes system for the third time in two years. With the Menindee lakes storage levels already increasing as a result of high flows earlier this summer, there is limited capacity to manage the impending additional flow.

As a result, the NSW Office of Water and State Water Corporation began flood pre-release operations on Thursday 2 February 2012, increasing releases from 15,000 megalitres per day to a target of 29,000 megalitres per day by Tuesday 14 February. However, as the scale of flooding in the upstream valleys is becoming apparent, the rate of releases from
Menindee Lakes will now continue to rise further to target 35,000 megalitres per day by Friday 17 February. These releases to the Lower Darling will make room in the storage for the second period of high inflows that are expected to arrive in March and April 2012, and will protect the township of Menindee from extensive flooding. Currently the various flood peaks are still making their way along the Gwydir, Namoi, Moonie, Warrego and Balonne/Culgoa/Bokhara river systems. Flood flows from the Moonie, Namoi and Gwydir Rivers will flow into the Barwon-Darling system first, followed by flood flows from the other Queensland Rivers. The full extent of these flood flows into the Barwon-Darling system is not yet fully clear, but it is expected to be
significantly larger than last summer, with flood peaks even higher than those experienced in 1998. This could result in the largest flood in the Barwon-Darling system since 1976.

 

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Management of the Barwon-Darling floods of December 2010–April 2011

Content

Report by the NSW Office of Water describing the management of floods in the Barwon Darling River during the period December 2010–April 2011, including the operation of the Menindee Lakes and volumes to the Lower Darling and the Great Darling Anabranch

Report by the NSW Office of Water describing the management of floods in the Barwon Darling River during the period December 2010–April 2011, including the operation of the Menindee Lakes and volumes to the Lower Darling and the Great Darling Anabranch

 

Download  full report below

Water Report-January Queensland Murray Darling Valleys South-West Region 17th January, 2011

Abstract or description: 

The south-west region received widespread rainfall during the past week. Of note is the significant rainfall in the eastern parts of the region during this period particularly in the Upper Condamine and Gowrie/Oakey Creek systems. Rainfall totals of between 150–350mm were recorded throughout both systems which resulted in major flooding in most areas of the upper Condamine catchment. This flow has continued downstream and has been bolstered by additional inflow from Charleys Creek and other Condamine tributaries. This renewed flood flow will prolong the current flooding throughout the Balonne and lower Balonne systems. High rainfall in the Border rivers catchment is also resulted in major flood flows in the Dumaresq and Macintyre/ Weir Rivers.
The majority of Queensland’s Murray Darling river systems have been flowing at various rates
since late September/early October 2010 with the majority of the moderate to major flooding
occurring in the Condamine/Balonne river systems in the last few weeks. The major flow activity
at this point in time relates to the eastern part of the QMDB with high flows present in the Border, Moonie and Condamine/Balonne catchments. Currently the Bureau of Meteorology has announced flood warnings for the Condamine, Moonie and Macintyre/Weir Rivers.
Water harvesting announcements continue for the Border & Weir Rivers in the south, Lower
Balonne, Upper Condamine Water Management Area, North Branch of the Condamine River and the Warrego River.
The report is an update of streamflow conditions in the South West and was prepared on the 17th January, 2011. Please note that some flow data is not yet available for use in this report due to gauging station infrastructure damage in some areas as a result of the significant flood events seen in the South west region in the past month.

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Water Report Queensland Murray Darling Valleys South-West Region 2nd February, 2011

Abstract or description: 

Significant flooding events were recorded by the DERM streamflow gauging stations with hydrographers at their busiest across south west region during January, particularly the Condamine/Balonne River and Lower Balonne systems. Record heights were observed in parts of the system including Loudouns Bridge and Cotswold on the Condamine River, the Balonne River at Surat and the Culgoa River at Whyenbah. Good flows also occurred in the Border Rivers system and smaller flows were recorded in most other systems including the Paroo, Bulloo and Moonie Rivers. Currently, discharge is diminishing in all systems as the mass of flood water moves into NSW with little or no rainfall in the last week to bolster flow over most of
the region. While diminishing, significant flows are still being recorded in the Condamine/Balonne system, particularly in the Lower Balonne. The Bureau of Meteorology has announced minor to major flood warnings for the Balonne River. All eyes are currently focused on the approaching cloud mass of cyclone Yasi which could have some influence on rainfall and resurgence of flows in the southwest in the coming week.
Water harvesting announcements continue for the Border & Weir Rivers in the south, Lower Balonne and Upper Condamine Water Management Areas.
This report is an update of streamflow conditions in south west region and was prepared on the 1st February,2011

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Queensland Government

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National Landcare Programme