Welcome to our summary report on River Murray operations for the week ending 8 March 2017.
You can find the full weekly report under the River Murray system section of our website.
Rainfall and inflows
Persistent easterly winds across the Murray-Darling Basin during the last week resulted in heavy showers and storms over eastern areas, trending to mostly dry and quite hot weather in the west. Rain totals were fairly patchy and were generally highest along the eastern divide.
The highest weekly totals in Queensland fell over the Maranoa catchment and Darling Downs and included 86 mm at Cooby Creek Dam, 83 mm at Yuleba, 78 mm at Southwood and 73 mm at Surat. Totals in NSW included 105 mm at Coonabarabran, 80 mm at Narrabri and 52 mm at Mullaley. Rain was also quite heavy over the far south-east with totals up to 75 mm across the Snowy Mountains and 48 mm recorded at Cooma. Stream flows along upper catchment tributaries have mostly continued to recede. On the Mitta Mitta River, the flow at Hinnomunjie bridge has decreased below 200 ML/day for the first time this year. On the upper Murray, the flow at Biggara averaged around 180 ML/day. On the Ovens River at Rocky Point, the flow is currently fairly steady at just over 400 ML/day. This flow is being boosted by releases from Lake Buffalo, which is currently being slowly drawn down to facilitate planned maintenance works in a few weeks’ time.
Total in storage
Total MDBA storage decreased 149 GL this week, with the active storage now 6,002 GL (70% capacity).
River operations
At Dartmouth Reservoir, the storage volume remained steady at 3,000 GL (78% capacity). The release from Dartmouth, measured at Colemans, was held at 300 ML/day throughout the week. However, starting this Friday, releases will be increased and held at a rate close to 2,000 ML/day to provide a pulse of water into the lower Mitta Mitta River over several days. This action is being undertaken in accordance with agreed arrangements, when storage levels are relatively high, that permit greater flexibility and slightly higher release rates from Dartmouth Dam to help manage lower Mitta Mitta River water quality and ecosystem function.
The Hume Reservoir storage volume decreased 90 GL this week and is currently 2,206 GL (73% capacity). Releases were a little higher compared to last week, with an average of 14,500 ML/day.
At Lake Mulwala diversions into the Mulwala Canal and Yarrawonga Main Channel increased through the week. They are both now close to their highest rates for the season with a combined diversion of about 7,500 ML/day. Warm and dry conditions are expected to further push up demand during the coming week. The rate of increase in diversions earlier in the week above forecasts meant that the pool level temporarily decreased to a level just below 124.7 m AHD. The current pool level is 124.79 m AHD and is expected to remain around this mark over the coming days.
The release downstream of Yarrawonga Weir started the week at 9,500 ML/day but has now been steadily wound back to 8,000 ML/day. A similar rate is expected over the coming week. This reduction signifies the completion of delivery of an additional pulse of environmental water undertaken to help further boost flows along the length of the River Murray as well as stimulate native fish movement upstream. The current release of 8,000 ML/day continues to include a component of baseline environmental water and, at this stage, is expected to be maintained throughout March.
Inflows to the Edward-Wakool system have been fairly steady through the week, with around 1,550 ML/day flowing through the Edward River Offtake and just under 350 ML/day through the Gulpa Creek Offtake. At Stevens Weir, diversions to the Wakool Main Canal have averaged just over 1,000 ML/day, while the downstream flow target continues at the normal summer minimum of 600 ML/day. Downstream on the Wakool River, Stoney Crossing is steady at around 650 ML/day.
On the Goulburn River, the flow at McCoys Bridge is currently 4,300 ML/day and rising towards a peak expected over the coming weekend at around 4,500 ML/day. This flow is composed of an environmental pulse as well as IVT water that continues to be delivered to the Murray. Flow rates are expected to recede during the second half of March.
At Torrumbarry Weir, the downstream flow rate peaked at 7,100 ML/day on 6 March as environmental flows from both the Murray and Goulburn Rivers arrived. The flow is expected to remain above 6,000 ML/day for a few more days before receding. The pool level remains at the full supply level of 86.05 m AHD, while diversions to National Channel have increased to about 3,400 ML/day. Relatively high diversions (in excess of 3,000 ML/day) are expected to continue at National Channel during the next few weeks if the weather remains dry.
On the Murrumbidgee River at Balranald, flows have receded due to increasing demands upstream. The current flow is 800 ML/day with rates above the normal end of system target set to continue through March as traded water is delivered to the Murray.
Downstream at Euston Weir, the pool level has recently been held around 20 cm below the normal FSL as part of the weir pool variability program. However, the level is now being temporarily re-raised towards FSL in preparation for the Robinvale Euston 80 Ski Race, scheduled for the coming weekend. The level will be returned to the lower target (20cm below FSL) during the coming week. The flow rate downstream of Euston has decreased to around 5,000 ML/day and is expected to remain fairly steady for a few days before rates slowly increase as higher flows arrive from upstream.
On the Darling River system, total storage in the Menindee Lakes fell by 48 GL, to the current volume of 1,029 GL (59% capacity). The release from Menindee Lakes into the lower Darling River has been decreased to a target at Weir 32 of 2,250 ML/day. At the Lake Cawndilla outlet, releases of environmental water continue, with around 1,300 ML/day flowing into the Great Darling Anabranch.
At the confluence of the Darling and Murray Rivers at Wentworth, the flow is steadily receding, with the current flow at 6,600 ML/day. Flows less than 6,000 ML/day are expected later in the coming week. Downstream at Lock 7, the weir pool level has returned to its weir pool variability program target of around 45 cm below the normal FSL (22.10 m AHD). This reduction follows a short period during late February when the level was increased to FSL.
At Lake Victoria, the storage volume decreased by 11 GL to 441 GL (65% capacity) and will continue to decrease over the coming week. The flow into South Australia was maintained around a target of 8,000 ML/day for most of the week. However flow rates are now set to rise to undertake delivery of traded environmental water previously released from both Hume and Eildon Reservoirs. Over the next 7-10 days, releases from Lake Victoria will be managed to progressively increase flows across the border with a flow above 11,000 ML/day currently expected by the middle of March. Downstream at Lock 1, the flow is currently 4,600 ML/day and is expected to rise steadily during the next few weeks.
At the Lower Lakes, the 5-day average water level in Lake Alexandrina fell 7 cm to 0.66 m AHD. This drop occurred as a result of increased barrage releases, which have averaged around 7,500 ML/day over the last few days. With higher flows now in transit to the Lower Lakes and a relatively high level in Lake Alexandrina for this time of the year, operations have taken advantage of relatively calm conditions by boosting freshening flows into the Coorong. By targeting a higher proportion of this flow through the Goolwa Barrage, the release is also aiming to assist the on-going dredging effort by helping to scour deposited sand along the Goolwa Channel and around the Murray Mouth.
Please note: MDBA is undertaking website maintenance work from 5.00 pm Thursday 9 March until 9.00 am Wednesday 15 March. During this period, website access may not be reliable and Live River Data may not be up to date.
Photo courtesy Phil Cocks, WaterNSW.
A boat heads off downstream from Lock 15 at Euston.
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Published on:
Thursday, March 9, 2017