As well as the river operations information below, this week’s full report (on our website) includes a notice that the Mildura Weir pool will be drawn down in winter 2013, based on river conditions at the time.
MDBA active storage increased by 187 GL during the week and is currently 7,180 GL (84% capacity). At Dartmouth Reservoir, the storage increased by 24 GL and is now 3,153 GL (82% capacity). The release from Dartmouth, measured at Colemans, was 190 ML/day. At Hume Reservoir, the storage increased by 125 GL and is now 2,706 GL (90% capacity). The release from Hume was increased to 3,100 ML/day early in the week but was subsequently cut back to the minimum release of 600 ML/day following the rain. The release is expected to be increased again over the coming days to balance late season demands and transition to pre-release mode of operation to manage airspace through autumn and winter given the relatively early re-filling of the storage in March.
At Yarrawonga Weir, the pool level is currently 124.81 m AHD. Diversions through the Mulwala Canal and Yarrawonga Main Channel have remained relatively low during the week, while additional flow through the Mulwala Canal has been maintained and escaped to the Edward and Wakool Rivers to help maintain higher dissolved oxygen levels downstream. The release at Yarrawonga was decreased during the week and is currently at 9,500 ML/day.
On the Edward-Wakool system, flow through the Edward and Gulpa offtakes continued to fall away with flows currently at around 1,700 and 700 ML/day respectively. At Toonalook, the flow peaked at around 12,000 ML/day over the weekend and is now receding, while downstream at Stevens Weir the flow peaked at around 12,000 ML/day but has now decreased to 7,700 ML/day. On the Billabong Creek, the flow continues to rise at Darlot and is now at 3,500 ML/day, while downstream on the Wakool River, flows are rising at all gauges and a peak flow at Kyalite may exceed 15,000 ML/day during early April.
At Torrumbarry Weir, the flow has remained at around the 28,000 ML/day mark for most of the week and a slight rise to above 30,000 ML/day is expected over the coming weekend. At Swan Hill, the flow has crept higher and is now at 21,600 ML/day; while downstream at Euston, the river has continued rising with increasing input from the Murrumbidgee expected to push up the flow for several more weeks. The flow at Euston is now edging 30,000 ML/day and current forecasts suggest a flow in excess of 50,000 ML/day by mid April, depending on the timing and magnitude of flood inflows from the Murrumbidgee River. A similar flow rate is expected at Mildura in mid April. The proposed lowering of the Mildura Weir in April has now been re-scheduled for 2013 (see attached Media Release).
At Menindee Lakes, high inflows continue and are expected to start rising further as the main flood peak on the Darling arrives in early April. The storage volume eased by 9 GL this week and will likely not decrease by much more before re-commencing to fill over the coming weeks. The release (measured at Weir 32) remains at around 35,000 ML/day and the gates at Main Weir remain fully raised. Downstream on the lower Darling, the level at Burtundy continues to gradually rise and the river is now flowing at 17,500 ML/day. Flows are also increasing along the Great Darling Anabranch with return flow into the Murray River expected over the next several months.
The flow in the Murray at Wentworth has increased to 45,000 ML/day and may increase to about 65,000 ML/day by mid April.
Storage volume in Lake Victoria rose by 48 GL, to 550 GL during the week as water was captured to allow the demobilisation of works at Lock 4 and at Chowilla. The demobilisation has now finished and Lake Victoria is now expected to begin falling during the week as water is released from the lake in order to target less than 500 GL in storage by the end of March.
The flow to South Australia is now around 42,000 ML/day and expected to climb to around 60,000 or slightly above by mid to late April.
Due to the flow over Lock 1 now increasing to around 25,000 ML/day, the level in the Lower Lakes has remained fairly steady over the week with a fall of only 1 cm to 0.58 m AHD. The lakes have been targeting a level of around 0.5 m AHD in an effort to improve salinity in Lake Albert, but due to high inflows to the lakes and high water levels in the Coorong, increased releases have been difficult to achieve and hence the low target level has also not been possible to date.