River Murray operations 1-8 February 2017

10 February 2017

Welcome to our summary report on River Murray operations for the week ending 8 February 2017.

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

Rainfall and inflows

Rainfall in the Murray-Darling Basin this week mostly fell across South Australia, Victoria and the southern and eastern parts of New South Wales. Little or no rain was recorded in southern Queensland and western New South Wales.

In Victoria, the highest weekly totals included 83 mm at Mount Hotham AWS and 44 mm at upper Buckland in the upper northeast. In the Mallee, 46 mm was recorded at Berriwillock and 43 mm at Murrayville. Notable totals in NSW included 59 mm at Crookwell in the southern tablelands and 49 mm at Woolbrook in the northwest slopes. In South Australia the highest totals included 51 mm at Claypans, 49 mm at Mindarie, 44 mm at Swan Reach and 45 mm at Nildottie.

Rain this week prompted modest stream flow rises along the upper Murray tributaries. On the Mitta Mitta River, the flow at Hinnomunjie Bridge peaked at 750 ML/day. On the upper Murray at Biggara, the flow peaked at 700 ML/day. Flow along the Ovens River at Rocky Point peaked at around 1,300 ML/day.

Total in storage

MDBA total storage decreased by 117 GL, with the active storage currently 6,570 GL (76% capacity). This is around 1,000 GL above the long-term average and more than double the volume at the same time last year when the active storage was 3,098 GL (36% capacity).

River operations

System Operations

In January, demands and losses along the Murray system were lower than planned for, meaning that more water has been arriving at Lake Victoria than expected. This allows for deliveries in February, including from tributary inter valley trade (IVT) and from Menindee lakes to be reduced.  Recent rain has continued this trend, however heatwave conditions in the coming days are expected to increase demands and losses. 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

  • Dartmouth Reservoir’s storage volume increased 2 GL this week to 3,026 GL (78% capacity). The release, measured at Colemans gauge, increased from 300 ML/day to 5,000 ML/day on 8 February for the purpose of electricity generation. The duration of the increased releases is unknown and will be dependent upon electricity demand in the near future.
  • The Hume Reservoir storage volume fell by 53 GL this week to 2,487 GL (83% capacity). This compares with 1,109GL (37% capacity) at the same time last year. Based on current forecasts and estimated demands and losses along the Murray system, it is unlikely that Hume Reservoir volume will fall much below 50% capacity this water year. The release this week averaged around 10,000 ML/day. Downstream of Hume, the Kiewa River has provided an average of around 900 ML/day to the Murray.
  • The pool level at Lake Mulwala is currently around the full supply level (FSL) of 124.9 m AHD. Diversions to the major irrigation off-takes reduced this week in response to the rain. Mulwala Canal reduced from 5,300 to 3,400 ML/day and Yarrawonga Main Canal reduced from 1,500 ML/day to a low of 450 ML/day. Diversions are expected to increase over the coming week due to the forecast hot and dry conditions.
  • The release from Yarrawonga Weir has remained steady near 8,000 ML/day and would be lower without deliveries of environmental water. Currently, 1,500 ML/day of environmental water is being released for large bodied native fish and other environmental benefits along the River Murray. The target flow is expected to gradually increase over the coming week to around 9,500 ML/day where it will remain for around two weeks before being gradually reduced during March. Releases downstream at Yarrawonga Weir in autumn are likely to be lower than experienced over the last few years at this time of year due to downstream demands being supplemented by water from the Goulburn, Campaspe and Murrumbidgee Rivers, Menindee Lakes and Lake Victoria. This allows more water to be conserved in the major storages of Hume and Dartmouth than would otherwise have been the case.
  • On the Edward River system, the flow through the Edward offtake has continued to average close to 1,600 ML/day. The Gulpa Creek offtake has been reduced to 420 ML/day and is expected to lower to around 350 ML/day later in the coming week. Flow in the Edward system is being supplemented by inflows from the Edward Escape which has reduced from around 950 to 350 ML/day in response to reduced demand at Wakool Canal. Downstream at Stevens Weir the flow has fluctuated around an average of 860 ML/day and is expected to continue to target around 600 ML/day over the coming weeks.
  • The Goulburn River at McCoys Bridge has averaged around 1,300 ML/day. The flow is expected to remain around 1,200 ML/day during February – well above the minimum flow target of 350 ML/day, as inter valley trade (IVT) water is delivered to the Murray. If conditions remain dry, IVT deliveries can be expected to persist over the next few months to continue to help meet downstream demands. Planning is underway to combine environmental water with IVT deliveries to deliver a flow pulse in early March aimed at providing outcomes for both native fish and for water supply to the Murray. Further information will be available in coming weeks.
  • At Torrumbarry Weir, diversions to National Channel have been steady at 2,200 ML/day with a portion of this water provided to support Murray Cod in Gunbower Creek. Downstream of Torrumbarry Weir the flow is 4,900 ML/day and is expected to remain around this rate over the coming week.
  • On the lower Murrumbidgee River, deliveries of IVT to the Murray are continuing. The flow at Balranald averaged 2,000 ML/day this week, well above the February end of system target of 180 ML/day. IVT deliveries will continue at around this rate during February and are expected to continue into March, although at lower rates. Further information on IVT in the Murrumbidgee system is available from WaterNSW.
  • At Euston, the flow has averaged around 6,800 ML/day and is expected to ease to around 6,500 ML/day over the coming week. The lock at Euston remains closed due to repair works being undertaken on one of the upstream lock gates. In the coming weeks the Euston weir pool may be lowered below the FSL as part of weir pool variability but will be returned to near FSL during important recreational times.
  • On the Darling River, total storage at Menindee Lakes fell by 50 GL to a storage volume of 1,251 GL (72% capacity). The release at Weir 32 was gradually reduced to 4,000 ML/day this week and is expected to remain around this rate in coming weeks. The majority of this release is being sourced from Lake Menindee. Release of environmental water to the Great Darling Anabranch commenced late this week with around 1,100 ML/day being released via the Lake Cawndilla outlet. The release of environmental water, directed by NSW in association with the Commonwealth Environmental Water Holder, is expected to continue over the coming months with the aim of creating connectivity with the River Murray.
  • At Wentworth, the flow increased to 9,400 ML/day in response to recent rain, but will fall away over the coming week. The weir pool at Lock 9 is currently targeting 10 cm below FSL. Lock 8 weir pool continues to be lowered to target 50 cm below FSL, and is currently 38 cm below FSL. The weir pool at Lock 7 is currently 39 cm below FSL, but for operational reasons will be temporarily increased back to FSL over the coming week. Weir pool variability helps to restore a more natural wetting and drying cycle to riverbanks within the weir pool. More information on possible weir pool levels in the coming weeks is available on the MDBA website.
  • The storage volume at Lake Victoria fell 16 GL to 480 GL (71% capacity). The flow to South Australia averaged 10,200 ML/day this week and is expected to be gradually reduced throughout the remainder of February. This flow is above the normal entitlement flow due to delivery of environmental water to South Australia. Additional Dilution Flows to South Australia ceased on 2 February when the total volume in Menindee Lakes reduced below 1,300 GL.
  • At the lower lakes, the 5-day average level in Lake Alexandrina is 0.77 m AHD. Barrage releases have averaged around 7,000 ML/day.

Hume resevoir
Photo: Tom Zouch MDBA
Tourists enjoying a visit to Hume reservoir on 4 February with storage at 84% capacity.

 


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