The last week of River Operations saw MDBA active storage increase to its highest level in over 15 years. To find out more, read on…
Don’t forget that you can find the latest river data from the MDBA’s River Information Centre. There, you can find storage volumes and releases, river flow and levels, salinity data and the latest Flow & Salinity Forecast.
River Operations
MDBA active storage increased by 83 GL this week to 8,129 GL which is 95% of capacity and the highest active storage since October 1996 (see Figure 1 in the full weekly report).
Information on upper State shares within each storage can be found via the MDBA water accounting page.
At Dartmouth Reservoir, total storage rose by 57 GL to 3,439 GL (89% capacity) due to the increased inflows which peaked at around 10,000 ML/day over the weekend. At Hume Reservoir, peak inflows of around 32,000 ML/day arrived at the storage during Sunday and Monday. Total storage is now 2,929 GL (97 % capacity), a rise of 19 GL from last week. Release from Hume Reservoir reached 30,000 ML/day on Sunday and is currently being reduced as inflows recede. The level of Hume is currently being lowered to similar levels observed last week to provide limited airspace for flood mitigation.
The increased release from Hume Reservoir and higher inflows from the Kiewa and Ovens Rivers have led to peak inflows at Lake Mulwala of around 55,000 ML/day. At the time of writing the release from Yarrawonga Weir was 53,000 ML/day, which is expected to be close to the peak release. The release is expected to remain above 20,000 ML/day for at least another 10 days if the prolonged recessions in the upper tributaries continue as anticipated. The pool level is currently 124.76 m AHD and is expected to remain in the target range of 124.6 to 124.9 m AHD during this event.
Downstream on the Edward River, flows at Toonalook have been relatively steady at around 6,200 ML/day during the week but will increase as the higher flows arrive from upstream. Similarly, at Deniliquin, flows will rise during the coming week with peak flows expected to exceed 10,000 ML/day in late July. At Stevens Weir, the release has been steady at around 4,500 ML/day and the pool level has increased by 8 cm to 4.74 m. In the Wakool River at the Barham-Moulamein road, flows have increased from 100 to 700 ML/day in the last week and continued rises will occur in the Wakool over the coming weeks.
On the Goulburn River at McCoys Bridge, flows have increased from around 14,000 to around 19,000 ML/day which is near the expected peak flow of about 21,000 ML/day. The Goulburn waters will combine with those from the Murray and at Torrumbarry Weir release is expected to exceed 30,000 ML/day over the coming weekend. At Torrumbarry Weir the gates are being lifted clear of the water in order to allow free flow conditions for fish and to clear debris from the gates which has built up with the higher flows this week. In order to achieve this, the pool level immediately upstream of the weir will be temporarily lowered over the next 3-5 days, however with high flows, there should be little observable change in the upper weir pool level. Overbank flows have been entering the Koondrook-Perricoota Forest for over a week, and with the high flows past Torrumbarry expected into August, forest outflows will increase and contribute to higher flows in the Wakool River over the coming weeks.
On the Murrumbidgee River, release from Burrinjuck dam peaked at 12,000 ML/day on 17 July and is now at around 8,000 ML/day. Downstream at Gundagai, the flow is now a little over 20,000 ML/day. These flows mean that high flows now at Balranald (currently around 10,000 ML/day) will persist for several weeks to come. At Euston Weir the flow increased from 25,000 to 30,000 ML/day and is expected to rise steadily during the coming week.
Total storage in Menindee Lakes is now 1,966 GL (114% capacity), up 18 GL from last week and is expected to continue slowly increasing during the coming week. The release is currently targeting an average daily release of 500 ML/day, however, with renewed stream rises in several Barwon-Darling tributaries, it is likely that modest releases above minimums will be required in the coming months. Downstream of the lakes at Burtundy, the flow continued to fall gradually during the week, with a reduction from 2,250 to 2,000 ML/day.
At Lake Victoria, the level continues to be slowly decreased, as there is sufficient water in transit to enable a delay in the filling of Lake Victoria. The total storage has decreased this week by 11 GL to 469 GL (69% capacity). The flow to South Australia rose from around 26,000 to 31,000 ML/day during the week and is expected to continue gradually increasing in the coming days.
At the Lower Lakes, the 5-day average level at Lake Alexandrina increased to 0.79 m AHD and will be held around this level for the next 7-10 days as part of an on-going operation strategy to decrease salinity levels in Lake Albert. Salinity in Lake Albert has now remained at or below 4,000 EC units since the beginning of July.
Plots showing short term forecast flows and levels for selected key sites are updated each week and are available on the MDBA website at http://www.mdba.gov.au/water/river_info/river_flows.