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River Murray operations 17 August

Welcome to our report on river operations in the Murray for the river week ending 17 August 2016.

You can find the full weekly report including more rainfall and inflow figures, pics, graphs and data as a word or PDF document under the river info section of our website.

Rainfall and inflows

Last week, a trough moving across the north of the basin produced showers and thunderstorms with light to moderate rainfall in southern Queensland and northeast New South Wales, while high pressure cells have dominated over southern Australia. Light to moderate falls were recorded in southeast South Australia, Victoria and southern New South Wales.

Rainfall totals between 10 mm and 50 mm were recorded in South Australia’s southeast, much of the southern and alpine regions in Victoria and in southeast Queensland.

Over the coming 8 days the Bureau of Meteorology is forecasting over 15mm for much of the basin with some regions forecast to receive over 50 mm.

Stream flows in the upper Murray tributaries have continued to recede given there was little rainfall over the last week. The flow in the Mitta Mitta River at Hinnomunjie has reduced to 1,400 mega litres per day whilst the upper Murray at Biggara has decreased to 1,700 megalitres per day. On the Ovens River, the flow at Wangaratta fell from 12,300 megalitres per day to 7,500 megalitres per day.

Whilst inflows have receded over the last week the upper catchments are still very wet and further rainfall could see rises in the tributaries.

Total in storage

MDBA total storage increased by 133 gigalitres this week, with the active storage now 4,988 gigalitres (58% capacity).

River operations

At Dartmouth Reservoir, the storage volume increased by 20 gigalitres to 2,150 gigalitres (56% capacity). The release from Dartmouth is currently 1,200 megalitres /day due to the release of AGL entitlement water for hydroelectricity generation.

At Hume Reservoir, the storage volume increased by 129 gigalitres to 2,475 gigalitres (82% capacity). As storage levels rise over the coming weeks MDBA may soon commence ‘airspace management’ releases aimed at providing a measure of flood protection, balanced against ensuring Hume fills prior to demand emerging and maximising water availability.

MDBA is operating Hume Dam in accordance with arrangements agreed by the joint governments of the Commonwealth, New South Wales, Victoria and South Australia. These are outlined within a set of Objectives and Outcomes for river operations in the River Murray System and state that the order of priority for dam operations is:

  • firstly, protect the security of assets (e.g. Hume Dam)
  • secondly, to maximise the available water at the end of the relevant flooding episode
  • thirdly, subject to the foregoing items, limit flood damage to downstream communities and increase benefits to the environment and public amenity.

Given recent inflows and rainfall predictions, it is likely that Hume Reservoir will fill. However it is not yet assured that the dam will fill and historical records show that conditions can quickly turn dry.

The primary role of Hume Dam is water conservation. In recent weeks, by capturing significant inflow events, Hume Dam has provided considerable flood protection to communities downstream. However, as the storage approaches its full supply level (3,005 gigalitres), the dam will have reduced capacity to mitigate flood events. Further details about flood management at Hume Dam are available on the MDBA website. Regular updates on Hume storage levels and releases will be provided in future weekly reports, however communities are reminded that all Flood Watches and Warnings are issued by the Bureau of Meteorology.

Environmental releases from Hume Dam commenced on Tuesday, and are currently 2,000 megalitres per day.

These releases are supplementing the receding inflows from the Kiewa and Ovens rivers to target a maximum river level of 3.0 m at Tocumwal or roughly 15,000 megalitres per day downstream of Yarrawonga.

Whilst flows along the Murray have been high over the last month, they would naturally have been much higher without storages to capture these inflows.

Environmental releases for Barmah-Millewa forest are augmenting regulated flows to restore ‘gaps’ in the hydrograph resulting from stored inflows.

Targeting a river level of 3.0 m at Tocumwal downstream of Barmah-Millewa forest is aimed at maintaining low level inundation of the forest. Subject to consultation with affected landholders, the target may subsequently be increased to a maximum level of 3.3 m at Tocumwal (~18,000 megalitres per day).

The release of environmental water from Hume Dam will be ceased if the rain forecast, or observed, risks flows rising above the target.

Flows downstream of Yarrawonga Weir have attenuated significantly through Barmah and Millewa forests with flows of 19,900 megalitres per day at Barmah and 10,200 megalitres per day at Toonalook respectively.

On the Edward River, the flow through the Edward Offtake, 2,050 megalitres per day, and the Gulpa Offtake, 750 megalitres per day, have contributed to the Toonalook flow.

At Stevens Weir, the gates have been raised and a peak flow of 10,500 megalitres per day passed on Monday with flows currently 9,900 megalitres per day. Onto the Wakool River, small returns from the natural flooding of the Koondrook-Perricoota Forest are expected to enter the Wakool River over the coming week through Thule and Barbers Creeks. At Kyalite the flow is currently 8,000 ML/day and rising as the returns through Millewa forest make their way through the Edward-Wakool system.

Inflows to the Murray from the Goulburn River receded this week to 6,500 megalitres per day at McCoys Bridge. On the Murray at Torrumbarry Weir, the downstream flow peaked at 32,200 megalitres per day last Thursday and is currently 28,000 megalitres per day. Gunbower and Koondrook-Perricoota Forest have been naturally inundated since early August due to the high flows at Torrumbarry. Inundation of these sites would have been significantly higher without regulation.

Following a winter drawdown, Torrumbarry weir pool is currently 85.80 m Austalian Height Datum (25 cm below Full Supply Level) and will be further raised close to Full Supply Level in the coming weeks.

At Balranald on the Murrumbidgee River, the flow continues at 8,400 megalitres per day. Downstream on the Murray at Euston, the flow is 32,500 megalitres per day and the Euston weir pool is currently around 10 cm below Full Supply Level.

On the Darling River at Menindee Lakes the storage increased 6 gigalitres to 160 gigalitres (9% capacity).

Releases from Lake Wetherell into the lower Darling River commenced 29 July. Releases at Weir 32 are currently 170 megalitres per day and the block banks across the Darling have been removed with the flow at Burtundy currently 1,000 megalitres per day

Given the high flows in the Murray at Wentworth only a minor, and short-lived, rise in salinity is expected as the flow front from the Darling passes downstream into South Australia.

On the Murray at Lock 9 the weir pool is currently 7 cm above Full Supply Level and at Lock 8 the weir pool target is 50 cm above Full Supply Level. The river is flowing freely through

Lock 7 as the stop logs have been fully removed. The higher flows are resulting in the current river height being around 80 cm above Full Supply Level. The gates at the Mullaroo offtake regulator have been laid flat to maximise the flow into the Mullaroo Creek.

The total storage at Lake Victoria was reduced by 22gigalitres this week to 557 gigalitres (82% capacity). MDBA has lowered Lake Victoria over the last month to minimise disturbance to Aboriginal cultural heritage material. MDBA operates in accordance with the Lake Victoria Operating Strategy (LVOS), which requires the period of time that the water level in Lake Victoria is held high to be minimised in order to limit erosion and allow for revegetation to protect important cultural heritage. The MDBA is now beginning to reduce the outflows from Lake Victoria to maintain the Lake Victoria level. The MDBA will continue to assess the upstream inflows to determine when to refill Lake Victoria.

The flow to South Australia averaged 28,000 megalitres per day this week and is expected to average a similar rate over the coming week. Whilst it is unusual, it is not unprecedented to see such unregulated flows at a time when water allocations remain low.

At Chowilla, a range of environmental watering actions are being considered. Operations to further test the Chowilla regulator and ancillary structures commenced Wednesday 10 August. Testing involves raising water levels behind the Chowilla regulator. The event will target an initial Chowilla regulator height of up to 19.4 m Australian Height Datum (3.1 m above normal pool level) and if flow conditions increase, then the target height could be increased to around 19.75 m Australian Height Datum. Engineering checks and monitoring of creek and floodplain conditions will be undertaken throughout the event to ensure the regulator and ancillary structures are operating as designed. Lock 6 will be progressively raised by up to 62 cm to ensure flow through the Chowilla anabranch is maintained. This raising of the Lock 6 water level is important for the management of water quality and protection of important habitat for native fish.

Flow downstream of pipeclay weir (source  SA Water).
Flow downstream of pipeclay weir (source SA Water).

Downstream at the Lower Lakes, flows through the barrages have remained high this week. Releases are being made to help improve water quality in Lake Albert and the Coorong, and to assist in scouring sand from the Murray Mouth. The 5-day average water level in Lake Alexandrina has remained relatively steady this week at around 0.72 m Australian Height Datum.

Reducing the water level in Lake Alexandrina enables the higher salinity water of Lake Albert to drain out. Once Lake Alexandrina is raised again fresher water can then flow back into Lake Albert.

The current lake level cycling operation has been made possible by favourable tidal and weather conditions combined with the assurance of high unregulated flows passing over the SA border which will enable the Lower Lakes to be raised again in the future.

Salinity levels at Lake Albert have already decreased significantly in recent months, down from an average of around 2,250 EC (μS/cm) in April 2016 to current levels of around 1,700 EC (μS/cm). It is anticipated that there will be further reductions in Lake Albert salinity levels as a result of current operations.

The MDBA has refreshed its Live River Data site based on feedback from users.

We now have three different views: system view, list view and map view. We encourage you to visit the help page to find more information about the features of the new site, see See the latest river information by visiting

Homepage Image: 
Flow downstream of pipeclay weir (source  SA Water).
Site Context: 
Grid View Image: 
Flow downstream of pipeclay weir (source  SA Water).
Published on: 
Friday, August 19, 2016

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