This week’s report details the increase in the amount of water in storage across the Basin. The full report is available from our website.
River Operations
MDBA active storage increased by 56 GL during the week to 7,985 GL (93% capacity). At Dartmouth Reservoir, the total storage increased by 23 GL to 3,365 GL, which is 87% capacity.
At Hume Reservoir, the storage volume increased by 17 GL to 2,883 GL (96% capacity) and the release has been reduced to 9,500 ML/day. Releases are now being managed to slowly increase the storage level following the latest review of the airspace target, which has been reduced due to the latest short and medium term rainfall forecasts. Operations are currently aiming to increase the storage to around 97% capacity by mid July (70-80 GL of airspace) however this target may change again and airspace re-gained if higher rainfall is forecast over the coming weeks.
Downstream at Yarrawonga, the pool level in Lake Mulwala has remained fairly steady throughout the week and is currently 124.73 m AHD. NSW has advised of an early start to the irrigation season with channel filling via Mulwala Canal to begin next week. Release from Yarrawonga Weir is fairly steady at 20,000 ML/day and is expected to remain close to this rate over the coming days.
Downstream at Barmah, the river is continuing to rise with over-bank flows passing into the Barmah-Millewa forest. The flow at Barmah gauge is now 9,200 ML/day and is expected to exceed 10,000 ML/day during the week ahead.
On the Edward-Wakool system, about 2,200 ML/day is passing through the Edward and Gulpa offtakes, while downstream at Toonalook the flow has increased to 5,500 ML/day and is expected to exceed 6,000 ML/day this week. At Stevens Weir, the weir pool has increased to 4.42 m on the local gauge and the downstream release is 2,800 ML/day, with 440 ML/day being passed through the Yallakool offtake and 840 ML/day through the Colligen Creek offtake. Downstream on the Edward River at Moulamein the river is still falling slowly however renewed rises are expected in just a day or two once higher flows arrive from upstream.
On the Goulburn River, the flow at McCoys has continued rising during the week and is now at 10,800 ML/day. Goulburn-Murray Water advises that the flow is expected to increase beyond 13,000 ML/day in about a week’s time. At Torrumbarry Weir the pool has been lowered to 85.74 m AHD or 31 cm below the normal operating level in order to manage higher flows. The pool will be temporarily lowered further in the coming days. The flow has now reached 18,200 ML/day at Torrumbarry and will continue to steadily increase with a flow peak close to 22,000 ML/day likely in the week ahead.
On the Murrumbidgee River, the flow at Balranald has crept up slowly but is now fairly steady at around 9,500 ML/day. At Euston Weir, the flow is also increasing and should exceed 20,000 ML/day in a day or two with further rises over the next two weeks taking flows towards 30,000 ML/day. To assist with these higher flows, the pool level at Euston will be lowered by about 30 cm during the coming week and the level will be operated in a range between 47.6 m AHD (Full Supply Level) and 47.3 m AHD (0.3m below FSL) over the next few months (see attached media release).
At Menindee Lakes, the storage increased by 9 GL, and the lakes remain surcharged at 1,927 GL (111% capacity). The release, measured at Weir 32, returned to the normal minimum for surcharged conditions of 500 ML/day early in the week. However, the release will now be pulsed to provide a variable flow several hundred ML/day above and below the target to help maintain water quality along the lower Darling River.
At Lake Victoria the rate of filling has been slowed further in line with the Lake Victoria Operating Strategy as there are now sufficient flows in transit to enable a later filling date. The storage increased by just 7 GL to 484 GL (71% capacity). The flow at Wentworth has remained fairly steady over the last few days at around 17,000 ML/day and the flow to South Australia has increased to 21,000 ML/day but should remain fairly steady over the next few days.
The flow over Lock 1 is currently 21,700 ML/day and the 5-day average level at the Lower Lakes has risen to 0.65 m AHD (0.10 cm below FSL). On-going inflows to the Lower Lakes and recent local rain have resulted in a continuing slow decline in salinity levels in Lake Albert with values below 4,000 EC recorded for several days this week. Water flowing through the Barrages has also maintained flows into the Coorong and out to sea via the Murray Mouth.