Another jam-packed edition of the full River Murray Weekly Report is available on the MDBA website in pdf and doc formats, with a wealth of data on river levels, flows, salinity and water storages. Or read on for the latest from River Murray operations…
MDBA active storage increased by 61 GL during the week to 8,046 GL (94% capacity). At Dartmouth Reservoir, the total storage increased by 17 GL to 3,382 GL, which is 88% capacity. Information on State shares within each storage can be found linked from the MDBA water accounting page, which is updated around the 15th of each month.
At Hume Reservoir, the storage volume increased by 27 GL to 2,910 GL (97% capacity) and with inflows now rising, the release has been increased to match inflows. With Hume Reservoir effectively full, inflows to the storage over the coming week will be passed downstream in order to maintain airspace (currently 94 GL) to assist in managing larger inflow events should they occur. It is likely that these spills from Hume will result in overbank flows in excess of 25,000 ML/day at Doctors Point over the coming week.
Downstream at Yarrawonga, the pool level in Lake Mulwala is currently 124.69 m AHD. Diversions through Mulwala Canal have commenced during the week for channel filling ahead of the up-coming irrigation season. The current diversion rate is 500 ML/day with rates up to 1,500 ML/day expected this week. Release from Yarrawonga Weir has remained quite steady at around 20,000 ML/day during the week, however higher inflows are in transit upstream, meaning a steady increase in releases will take place in the days ahead. At this stage, the release is expected to rise well above 30,000 ML/day in the next 4-6 days.
On the Edward-Wakool system, diversion through the Edward and Gulpa offtakes has increased slightly to around 2,400 ML/day. Downstream at Toonalook the flow has increased to 6,200 ML/day and is expected to remain fairly steady in the days ahead, however flows will rise again once the higher releases expected through Yarrawonga Weir make their way through the Millewa forest in the next few weeks. At Stevens Weir, the pool level has increased by a further 24 cm to 4.66 m on the local gauge. This is still around 0.5 m below the full supply level. Flow downstream of Stevens Weir has been held steady at about 4,300 ML/day and high flows are now being diverted through the Wakool River, Yallakool Creek and Colligen Creek offtakes. Downstream on the Edward River higher flows have arrived at Moulamein with an increase from 600 to 2,500 ML/day during the week. Further downstream flows are also increasing at Liewah, while on the Niemur River, fresh rises have started with a steady increase in flows expected to continue for at least the next week.
On the Goulburn River, the flow at McCoys has increased from 10,800 to 14,300 ML/day. Goulburn-Murray Water advises that the flow is expected to increase to around 16,000 ML/day in the next week, however with further rain forecast, the flow could continue rising beyond this level. At Torrumbarry Weir the pool has been raised again following a temporary lowering during the week. This operation was undertaken to buffer increasing flows to assist downstream works. The pool level is now at 86.04 m AHD (1cm below Full Supply Level). The flow downstream of Torrumbarry is 22,300 ML/day and is expected to rise steadily beyond 25,000 ML/day over the coming week. Flows above 30,000 ML/day may occur if Goulburn River inflows continue to increase with further rain.
On the Murrumbidgee River, the flow at Balranald has continued rising slowly and is now at 9,900 ML/day. Sustained high flows along the lower Murrumbidgee are expected for at least the next few weeks. At Euston Weir, the flow has increased to 24,900 ML/day and is expected to exceed 30,000 ML/day in around a week’s time. The pool level at Euston is currently 47.34 m AHD, which is 26 cm below the normal operating target of 47.60 m AHD.
At Menindee Lakes, the storage increased by 21 GL, with extra inflow resulting from heavy local rain on the surcharged lakes. The lakes are currently storing 1,948 GL (113% capacity). The release, measured at Weir 32, is currently 350 ML/day and continues to be varied around the current average release target of 500 ML/day to help maintain water quality along the lower Darling River. Downstream on the Great Darling Anabranch, flows continue draining into the River Murray upstream of Lock 9.
Figure 1. The Great Darling Anabranch below 10 Mile Bridge, 29 May 2012. Photo: Hugo Bowman, MDBA.
This water represents the final stages of the flow of floodwaters that originated in the upper Darling system following the major rain events of last summer.
At Lake Victoria, the storage decreased by 4 GL to 480 GL (71% capacity). The storage is now being decreased by around 2,000 ML/day as higher inflows in the upper catchments mean there is sufficient water in transit to fill Lake Victoria at a later date. Decreasing the storage level also provides benefits to foreshore vegetation in line with the Lake Victoria Operating Strategy.
The flow to South Australia has increased to 26,100 ML/day and is expected to increase to around 30,000 ML/day in the days ahead. The 5-day average level at the Lower Lakes has risen to 0.71 m AHD (0.4 cm below FSL). The lake levels are expected to continue rising slowly over the coming week.
Plots showing short term forecast flows and levels for selected key sites are updated each week and are available on the MDBA website.