River Murray operations 15-22 February 2017

24 February 2017

Welcome to our summary report on River Murray operations for the week ending 22 February 2017.

You can find the full weekly report under the River Murray system section of our website.

Rainfall and inflows

Rain in the Murray-Darling Basin this week mostly fell across southeast Queensland and northeast New South Wales. Little or no rain was recorded across the western parts of the Basin.

In Queensland, the highest weekly totals included 65 millimetres (mm) at Jandowae, 55 mm at Warwick and 53 mm at Ripple Downs in the Darling Downs, 60 mm at Roma in the Maranoa catchment and 54 mm at Derbyshire Downs in the Warrego catchment. The highest totals in NSW included 45 mm at Guyra and 43 mm at Glen Innes airport automated weather station (AWS) on the northern tablelands, 46 mm at Woolbrook and 35 mm at Pindari Dam on the northwest slopes and 37 mm at Pallamallawa on the northwest plains. Notable totals in Victoria included 22 mm at Mount Hotham AWS in the upper northeast.

Stream flows along upper Murray tributaries were mostly steady this week. On the Mitta Mitta River, the flow at Hinnomunjie bridge averaged around 280 megalitres per day (ML/day). On the upper Murray, the flow at Biggara averaged around 380 ML/day. On the Ovens River at Rocky Point the flow peaked at around 950 ML/day before receding to 600 ML/day.

Total in storage

Total MDBA storage decreased 151 gigalitres (GL) this week, with the active storage now 6,274 GL (73% capacity).

River operations

System Operations

In January and February, demands and losses along the Murray system have been lower than planned for, meaning that more water has been arriving at Lake Victoria than expected. In order to reduce the risk of water resource being spilled from Lake Victoria over the coming winter/spring, deliveries, including from tributary inter valley trade (IVT) and from Menindee lakes, continue to be reduced.  However, the Bureau of Meteorology’s latest outlook for autumn suggests rainfall is likely to be below average and temperatures are likely to be warmer than average. This means demands and losses may be high during autumn, so that deliveries may need to be increased in the future. Updates will be provided in coming weeks as flow rates across the system are adjusted in response to the observed and forecast weather and demands.

River Operations

  • At Dartmouth Reservoir, the storage volume decreased 5 GL to 2,999 GL (78% capacity). The release from Dartmouth, measured at Colemans, reduced from 2,500 ML/day back to 300 ML/day early in the week in response to reduced electricity demand.
  • The Hume Reservoir storage volume decreased 78 GL this week and is currently 2,367 GL (79% capacity). Releases have averaged around 12,800 ML/day.
  • At Lake Mulwala the pool level is currently at 124.76 m Australian Height Datum (AHD). Diversions at the major irrigation off-takes remain relatively low for this time of year with Mulwala Canal and Yarrawonga Main Channel averaging around 3,700 ML/day and 1,500 ML/day respectively. Releases downstream of Yarrawonga averaged around 9,900 ML/day. The flow is expected to be around 9,500 ML/day during the coming week, before receding to around 8,000 ML/day in early March. Over recent months, flows have been boosted using additional environmental water. This is expected to continue into March. The intention of these environmental releases is to allow connectivity with Toupna creek downstream of Yarrawonga for the benefit of native fish as well as boosting overall flow rates along the Murray including into South Australia.
  • Inflows to the Edward-Wakool system have remained steady. Edward and Gulpa Creek off-takes are currently targeting around 1,550 ML/day and 350 ML/day respectively. At Stevens Weir, the flow target continues at the normal summer minimum of 600 ML/day, while downstream on the Wakool River, the flow at Stoney Crossing has eased to about 700 ML/day.
  • Reports from the Deniliquin RSL 2017 Fishing Classic (see photo below) of catches of a number of large Murray Cod in the Stevens Weir pool show that large fish are still around after the recent hypoxic event. During the flooding in spring 2016, dissolved oxygen levels in the Edward River at Toonalook and Deniliquin fell below 1 mg/L in October causing fish deaths. The Commonwealth Environmental Water Holder with the co-operation of Murray Irrigation Limited (MIL) delivered significant volumes of environmental water via MIL’s irrigation network and Edward escape to provide refuge for fish in the Edward River during this period. Whilst it is difficult to determine if the fish caught (and released) over the weekend survived due to this refuge, this weekend’s result is a positive sign.

Edward River Deniliquin RSL 2017 Fishing Classic.
Early morning start on the Edward River for contestants at the Deniliquin RSL 2017 Fishing Classic over the weekend. Photo courtesy Wil Lucardie, MDBA.
  • On the Goulburn River, the flow at McCoys Bridge has continued at rates above the normal end of system target with the delivery of inter valley trade (IVT) water to the Murray. The current flow rate is 1,150 ML/day. Late in the coming week, flow rates are expected to rise due to delivery of a flow pulse combining environmental water with IVT deliveries to provide outcomes for both native fish and for water supply to the Murray. In response, flows on the Murray are expected to vary over the coming weeks. For more details see the media release.
  • At Torrumbarry Weir, National Channel is currently diverting about 2,200 ML/day. Diversions are expected to increase to around 3,000 ML/day in the coming week in preparation for meeting autumn watering demands. The release downstream of the weir increased during the week from 5,000 ML/day to 6,400 ML/day.
  • On the Murrumbidgee River at Balranald, flows continue at rates above the normal end of system target due to the on-going delivery of IVT to the Murray. The flow is currently 1,800 ML/day, and is expected to recede to around 600 ML/day in March.
  • At Euston, the weir pool level is currently 9 cm below the full supply level (FSL). As part of the on-going program of weir pool variation along the mid Murray weirs, the pool level will be varied over the coming months to restore a more natural wetting and drying cycle to benefit the riverine environment. During known recreational events such as the up-coming Robinvale Classic water ski race in March, operations will target a level close to FSL to help with local community requirements as much as practicably possible. The release downstream of the weir has averaged around 7,500 ML/day.
  • On the Darling River system, total storage in the Menindee Lakes fell by 57 GL. The current storage volume is 1,129 GL (65% capacity). The release from Menindee Lakes, measured at Weir 32 is currently 4,000 ML/day. In response to reduced River Murray system demands, releases are expected to gradually ease over the coming week (see media release for more details). At the Lake Cawndilla outlet, releases of around 1,000 ML/day are delivering environmental water to the Great Darling Anabranch.
  • Downstream at Lock 7, the weir pool level has recently returned to around the normal FSL (22.1 m AHD) due to operational reasons. The pool level will be gradually lowered again to around 50 cm below FSL in the coming weeks as part of the on-going weir pool variability program.
  • At Lake Victoria, the storage volume decreased by 12 GL to 453 GL (67% capacity) and will continue to fall over the coming weeks. The flow into South Australia averaged around 8,800 ML/day during the week with the continuing delivery of environmental water boosting flows above the normal base entitlement rate. Downstream at Lock 1, the flow is currently 5,700 ML/day.
  • At the Lower Lakes, the 5-day average water level in Lake Alexandrina fell 2 cm to 0.75 m AHD. The average total barrage release was around 2,000 ML/day. Releases were restricted at times to manage reverse flows of seawater from entering the Lower Lakes due to the prevailing winds and large swells.

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