River Murray Weekly Report For the week ending Wednesday, 20 February 2019 Trim Ref: D19 8405 Rainfall and inflows There was little to no rainfall across the Murray-Darling Basin this week, with only small patches of light rainfall recorded in New South Wales and Queensland (Map 1). Map 1 - Murray-Darling Basin rainfall map week ending 20 February 2019 (Source: Bureau of Meteorology). In comparison to the previous week where tributaries increased with widespread rainfall, most upper Murray tributaries have receded with dry conditions this week. The flow in the upper Mitta Mitta River at Hinnomunjie fell from 190 ML/day to the current flow near 140 ML/day; likewise the upper Murray at Biggara eased from 160 to 100 ML/day. Downstream of Hume Reservoir, inflow from the Kiewa River at Bandiana averaged 210 ML/day, while the Ovens River flow reduced from 340 ML/day to 240 ML/day through the week at Wangaratta. Subscribe to the River Murray Weekly Report River Data website Water in Storages River Murray Weekly Report Photo 1: Swampy Plain river upstream of Khancoban in the Snowy Mountains (Photo courtesy: Tom Zouch, MDBA) Subscribe to the River Murray Weekly Report River Data website Water in Storages River Murray Weekly Report River operations • Transfers between Dartmouth to Hume winding down • Delivery of Goulburn Valley IVT water via the Goulburn River to ease • Reductions in Murray Irrigation Limited escapes bypassing water around the Barmah Choke to begin • Euston weir pool level returning to the full supply level • Flow over Weir 32 in the lower Darling River ceased System operations Following an extended period of near capacity flows and transfers to ensure supply through the system, latest operations forecasting is indicating flows through the system can now start to be eased. As we move into autumn and temperatures and peak demands start to decrease, MDBA will continue reviewing targets and flow reductions will be made where possible. Initial changes will include reductions to release rates from Dartmouth Reservoir, IVT delivery rates from the Goulburn system and transfers around the Barmah Choke via MIL channel escapes. These reductions will be an on-going adaptive transition over the coming weeks and will be updated as demand and storage flow forecasts are further revised. River operations The MDBA active storage volume decreased by 101 GL this week to 3,521 GL (40% capacity). The Dartmouth Reservoir storage volume decreased by 39 GL to 2,495 GL (65% capacity). Transfers from Dartmouth to Hume begun to reduce this week as climatic conditions and system demands eased. The release from Dartmouth reservoir, measured at Colemans, reduced from 5,000 ML/day to 4,600 ML/day and is forecast to continue to gradually decline over the coming weeks. At Hume Reservoir, the storage volume continued to decline, reducing by 52 GL to 870 GL (29% capacity). The release from Hume is currently targeting around 12,100 ML/day. Downstream at Lake Mulwala the level is currently 124.75 m AHD, which is within the normal operating range (124.6 to 124.9 m AHD). Diversion to Yarrawonga Main Channel averaged near 540 ML/day, while on the New South Wales side Mulwala Canal diversion averaged around 3,400 ML/day. Of the diversion to Mulwala Canal, approximately 2,200 ML/day is being diverted around the Barmah Choke through Murray Irrigation Limited (MIL) infrastructure and released into the River Murray (Perricoota escape), Wakool River (Wakool escape), Edward River (Edward escape) and Billabong Creek (Finley escape). As demands across the system continue to ease water being bypassed around the Barmah Choke via the MIL escapes will begin to be reduced, starting with the Edward, Perricoota and Finley Escape, which will start reducing in the coming days. On the Victorian side, around 120 ML/day continues to travel through Yarrawonga Main Channel and into the Broken Creek, again to meet demands downstream of the Barmah Choke. The release from Yarrawonga Weir was reduced this week from 8,800 ML/day to a target of 8,200 ML/day. The release is expected to continue to decline possibly to 8,000 ML/day. Flows at the Edward River and Gulpa Creek offtakes are currently around their normal summer regulated flow rates of 1,600 ML/day and 350 ML/day. Diversion into Wakool Main Canal averaged around 90 ML/day, and Wakool, Yallakool and Colligen offtakes are passing around 50, 400 and 410 ML/day respectively. This week, the flow in the Edward River downstream of Stevens Weir continued to target channel capacity of around 2,700 ML/day and may decrease slightly as the MIL escapes are reduced. Inflow to the Murray from the Goulburn River, measured at McCoys Bridge, is currently falling and is near 2,600 ML/day. The flow rate will continue to gradually reduce in the coming week to reach around 2,000 ML/day. The majority of this flow is Goulburn Valley Inter Valley Trade (IVT) water that is being delivered to help meet demands on the River Murray as a result of trade from the Goulburn to the Murray valley. The rate at which water is being traded out of the Goulburn Valley into the Murray has slowed. This, along with reduced demands during autumn, means delivery rates in March may continue to ease. Information regarding current opportunities for allocation trade between the Goulburn and Murray valleys is available at the Victorian water register website. Subscribe to the River Murray Weekly Report River Data website Water in Storages River Murray Weekly Report National Channel diversions remained around 2,000 ML/day this week. Diversions are expected to reduce to 1,750 ML/day next week and remain around this rate into the first weeks in March. The Torrumbarry Weir release was steady, averaging 7,700 ML/day, and is expected to gradually fall over the coming week. Lock 26 at Torrumbarry has been closed to undertake urgent repairs. This temporary closure of the lock will not affect the normal operation of Torrumbarry Weir in terms of river flow and water supply. More information can be found on the Goulburn-Murray Water website. This week inflows from the Murrumbidgee River, measured at Balranald, increased from 780 ML/day to 1,200 ML/day. This is above the normal February end of system target flow of around 180 ML/day. This higher flow is being targeted to help improve water quality in the lower reaches of the Murrumbidgee River and is being supplied by environmental water holders. More information regarding this water for the environment can be found on the MDBA website. The Murrumbidgee IVT balance is currently only 1.0 GL, preventing the MDBA from calling water from this valley to help meet Murray system demands. At Euston, the weir pool, which has been held 20 cm above the full supply level (FSL) during summer to mitigate against heatwaves and sudden spikes in irrigation demand, is being gradually lowered back to FSL for the beginning of autumn. The downstream release increased to 9,500 ML/day and will continue to rise slightly as water is released to lower the weir pool. Downstream at Mildura, the weir pool is currently at FSL. The release downstream has averaged around 8,000 ML/day and will rise as higher flows pass from the Euston weir pool lowering. The Menindee Lakes storage volume decreased by 4 GL to 31 GL (2% capacity). WaterNSW continues to manage the Menindee Lakes in accordance with the Lower Darling Annual Operations Plan. As part of drought contingency measures within this plan, WaterNSW has installed four temporary block banks across the lower Darling below Pooncarie near Jamesville, below Burtundy near Ashvale, and upstream of Pooncarie at Court Nareen and Karoola. Water held in these pools will assist in maintaining supply to domestic, stock and permanent plantings along the lower Darling. The release from Weir 32 ceased on 12 February. WaterNSW has advised that releases at Weir32 are only planned to recommence when sufficient inflows are received into the Menindee lakes (inflows are currently zero). Water restrictions remain in place across much of New South Wales as a result of the extensive and on-going drought conditions. A red level warning (high alert) for blue-green algae is current at a number of sites along the Darling River including Menindee Lakes. A summary of alert levels in New South Wales is available on the WaterNSW website. Current environmental conditions are well suited to algal growth due to prevailing hot weather and warm water temperatures and low or no flow conditions. The poor water quality conditions in the river has led to fish deaths in the lower Darling River. More information regarding the water quality conditions of the lakes and the lower Darling is available at the WaterNSW website. Information on factors that affect fish is available from NSW Department of Primary Industries website. Information on drought impacts across the Murray-Darling Basin including on fish and operations is available on the MDBA website. At Wentworth Weir, operations continue to target a pool level of around 10 cm above the full supply level to assist pumpers in the upper reaches of the Darling River arm of the weir pool. A red alert warning (high alert) for blue- green algae is current for the Wentworth Weir pool, from Merbein downstream to the weir. The downstream release averaged 7,500 ML/day and is expected rise late in the coming week. The Lock 9 weir pool is currently around 10 cm below FSL. At Lock 8, the weir pool is targeting 60 cm below FSL and the Lock 7 weir pool is targeting 50 cm below FSL.