River Murray operations 4-12 April 2017

13 April 2017

Welcome to our summary report on River Murray operations for the week ending 12 April 2017.

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

Rainfall and inflows

Early in the week, an inland surface trough over western Queensland and New South Wales was responsible for isolated thunderstorms which delivered rain across parts of northern New South Wales and southern Queensland. Later in the week a cold front and low pressure system with thunderstorms produced moderate to heavy falls across parts of central and north-eastern Victoria and south-eastern New South Wales.

Highest weekly rainfall totals were recorded in the Snowy Mountains and southern ranges. In Victoria the highest totals included 97 mm at Rocky Valley and 75 mm at Mount Hotham AWS in the north-east, and 62 mm at Lake Eppalock and 52 mm at Strathfieldsaye in the upper north. In NSW, 83 mm was recorded at Perisher Valley AWS and 74 mm at Thredbo in the southern tablelands (both just outside the south-eastern boundary of the Basin catchment) and 56 mm at Cabramurra AWS and 43 mm at Khancoban AWS on the southwest slopes. Notable totals in Queensland included 22 mm at St George airport in the Maranoa catchment and 20 mm at Whyenbah in the Warrego catchment.

Stream flows in the upper Murray tributaries increased in response to the rainfall this week. On the Mitta Mitta River, the flow at Hinnomunjie Bridge reached its highest level since late January, peaking at 1,500 ML/day. On the upper Murray at Biggara the flow reached around 1,050 ML/day. Downstream of Hume Reservoir, the Kiewa River at Bandiana and the Ovens River at Wangaratta peaked around 850 ML/day and 1,100 ML/day respectively.

Total in storage

Total MDBA storage decreased by 99 GL this week, with active storage now 5,320 GL (62% capacity).

River operations

System Operations

Similar to the last few weeks, operations continue to focus on releasing sufficient water from storage to meet system demands and steer towards targets at key locations, including Lake Victoria; while also aiming to conserve water for next season. The delivery of a small volume of inter valley transfer (IVT) water from the Goulburn to the Murray has commenced to meet end of system targets for Lake Victoria and to assist in maintaining minimum river levels throughout the mid-reaches of the Murray. Up to 20 GL is projected to be delivered throughout April.  

River heights are likely to remain steady along the mid-reaches of the Murray over the coming days, including the Easter period (see attached media release). River users are advised to maintain a close eye on conditions and keep up to date via livedata.mdba.gov.au when planning recreational or other activities.

River Operations

  • The storage volume at Dartmouth Reservoir increased by 4 GL this week to 2,998 GL (78% capacity). The release from Dartmouth, measured at Coleman’s, increased to 1,000 ML/day for two days over the weekend to maintain environmental condition in the lower Mitta Mitta River. The release is currently 300 ML/day and is expected to reduce to 200 ML/day in the coming week.
  • Storage in Hume Reservoir decreased this week by 70 GL and is currently 1,840 GL (61% capacity). Releases have varied throughout the week in response to fluctuating demands and losses in the Hume to Lake Mulwala reach and have averaged around 12,000 ML/day.
  • Diversions from Lake Mulwala have reduced over the last week in response to the rain and cooler conditions. Diversion to Mulwala Canal reduced from 4,900 ML/day to around 4,000 ML/day. Diversion to Yarrawonga Main Channel has decreased from 2,200 ML/day to around 1,300 ML/day. The water level at Lake Mulwala has remained fairly steady over the last week close to 124.8 m AHD, and is now sitting at 124.84 m AHD. The release downstream of Yarrawonga Weir has averaged around 8,000 ML/day and is likely to remain steady until after Easter.
  • Inflows to the Edward-Wakool system were reduced during the week. Flow through the Edward River off-take decreased to 1,430 ML/day while the Gulpa Creek off-take decreased to around 310 ML/day. Inflows from the Edward escape averaged around 730 ML/day. Diversions from the Stevens Weir pool to the Wakool Main Canal averaged 760 ML/day. Downstream of Stevens Weir the release averaged around 850 ML/day. Continuing higher inflows from the Billabong Creek (currently around 500 ML/day) have resulted in a flow in the Edward River at Moulamein above 1,200 ML/day.
  • On the Goulburn River the flow at McCoys Bridge averaged around 900 ML/day.  The flow will increase over the coming week to around 1,500 ML/day as Goulburn IVT water is delivered to the Murray during April to help meet system needs. A total of 20 GL of Goulburn IVT water is forecast to be delivered via Campaspe, Broken Creek and Goulburn systems.
  • Diversions from Torrumbarry Weir pool to National Channel have remained steady at around 3,200 ML/day. Due to diminished upstream inflows and steady irrigation demands, the release downstream of the weir reached a low of around 2,300 ML/day at the beginning of the week and has now increased to around 3,000 ML/day. As a result, the level further downstream at Swan Hill reached a minimum of 0.63m on the local gauge early this week and has since risen to 0.67m today. Levels are forecast to improve slightly over the coming days with the arrival of environmental flows from the Loddon River and Goulburn IVT water. 

Sunrise on the Murray at Tooleybuc
Photo courtesy Will Lucardie
Sunrise on the Murray at Tooleybuc
  • On the Murrumbidgee River at Balranald flows decreased steadily over recent days to a current rate of 2,750 ML/Day following a peak of 3,700 ML/Day over the weekend.  Flows are forecast to decrease toward minimums over the coming weeks as the environmental flow pulse continues to recede.
  • At Euston Weir, the pool level is currently 47.42 m AHD (18 cm below full supply level). As part of the weir pool variability program it is expected that this level will vary to around 20 cm below FSL over the coming weeks. The flow rate downstream of the weir has averaged around 6,700 ML/day, but is expected to reduce over the coming week toward 4,000 ML/day.
  • On the Darling River, total storage volume in the Menindee Lakes fell by 33 GL, to the current volume of 831 GL (48% capacity). The release from Menindee Lakes to the lower Darling River has remained steady this week and is currently targeting 1,000 ML/day at Weir 32. Releases from Lake Cawndilla have remained at around 1,100 ML/day as environmental flows are provided to the Great Darling Anabranch. So far around 57 GL of environmental water has been released to the Anabranch. This water is slowly making its way downstream and is likely to reach the Murray by the end of April.
  • At the junction of the Darling and Murray rivers at Wentworth, flows have increased steadily over the week and are currently 7,400 ML/day.
  • Weir pool variability continues at Locks 7 and 8 which are 86 cm and 93 cm below FSL respectively. Over the coming weeks Lock 7 and Lock 8 are expected to continue to vary at around these levels. In response to the lower pool level at Lock 7, the flow into Mullaroo Creek has reduced to around 400 ML/day.
  • Lake Victoria storage decreased by 1 GL this week to a storage volume of 325 GL (48% capacity). The flow to South Australia averaged 6,300 ML/day and is projected to decrease over the coming weeks. Downstream at Lock 1 flows have decreased to around 4,500 ML/day.
  • At the Lower Lakes, the 5-day average water level in Lake Alexandrina decreased by 2 cm to 0.57 m AHD. The barrages were closed during the second half of the week because of large swells and high tides.

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