This week’s full weekly report also includes a summary of rainfall, inflows and storages for the entire month of April.
Don’t forget – you can keep track of live river data on the MDBA website. But please share your thoughts on the Murray in the comments section before you go!
MDBA active storage increased by 136 GL during the week and is currently 7,415 GL (86% capacity). At Dartmouth Reservoir, the storage volume increased by 4 GL and is now 3,200 GL (83% capacity). The release from Dartmouth, measured at Colemans, remained at 200 ML/day. At Hume Reservoir, the storage volume decreased by 9 GL during the week and is now 2,609 GL (87% capacity). The release from Hume Dam increased slightly during the week and was then varied by small amounts in order to target a flow at Doctors Point that ranged from around 8,000 to 9,200 ML/day. The release over the coming days will depend on flow and demand responses to any rainfall.
At Yarrawonga Weir, the pool level is currently 124.68 m AHD, or 22 cm below full supply. Diversions through the Mulwala Canal and Yarrawonga Main channel have remained steady during the week averaging around 3,400 ML/day at Mulwala Canal and 150 ML/day at Yarrawonga Main Channel. The release from Yarrawonga Weir has been reduced slightly and is now at 7,000 ML/day. Additional in-channel dilution flow – being maintained using Commonwealth environmental water to assist in managing low oxygen water downstream – is expected to continue for another week.
On the Edward-Wakool system, diversion into the Edward River has remained steady with around 1,400 ML/day flowing through the Edward River offtake and 300 ML/day through the Gulpa Creek Offtake. Additional inflow from Mulwala Canal entering via the Edward Escape is now being reduced. This will decrease the flow at Stevens Weir over the coming week where the current release is 2,300 ML/day. Downstream on the Wakool River the flow at Stoney Crossing has receded to 1,900 ML/day and the flow at Kyalite is now estimated to be around 7,300 ML/day.
On the Goulburn River, the flow at McCoys Bridge reached a peak of 6,100 ML/day during the week and is now flowing at 5,100 ML/day. Goulburn-Murray Water has advised that the flow is expected to rise again to above 6,000 ML/day over the coming week. At Torrumbarry Weir, diversion into the National Channel was held at 1,500 ML/day for much of the week but is expected to increase to 2,000 ML/day during this week. The flow downstream of Torrumbarry is currently 10,700 ML/day and should decrease below 10,000 ML/day once diversions at National Channel are increased.
On the Murrumbidgee River, the flow at Balranald began to fall away during the week following a broad peak that held for about a week at a flow close to 30,000 ML/day. The river is now flowing at 24,000 ML/day and the river has dropped below the minor flood level.
Downstream at Euston, the Murray rose slightly higher to reach a peak of 37,900 ML/day on 1 May – slightly above the peak observed on 8 April. The flow should recede slowly over the coming days and may remain above 30,000 ML/day until the middle of this month.
On the Darling River, inflows to the Menindee Lakes remain high but have now started decreasing as flows in the Darling River and the Talyawalka Creek recede upstream. The average inflow over the past week was 49,000 ML/day – down from 60,000 ML/day during the previous week. The combined volume in the lakes increased by a further 162 GL to reach 1,926 GL, or 111% capacity. Release from the Lakes (measured at Weir 32) has been held this week at around 23,000 ML/day, and is expected to be held steady for several more days as inflows remain high to ensure the lakes remain below the full surcharge level. Current forecasts indicate the lakes should level out at around 2,000 GL, which is 50 GL below the full surcharge capacity.
Downstream on the lower Darling River, the flow at Burtundy has reached 20,000 ML/day and continues to rise very slowly towards a peak expected later in the month. For further information on the flood operations at Menindee Lakes, please refer to the NSW Office of Water website.
At Wentworth, the flow increased from 54,600 to 57,800 ML/day and the upstream pool is now 22 cm above the normal operating level. The flow is now expected to peak again during the coming week but should remain just below 60,000 ML/day. At Lake Victoria, the storage volume decreased by 21 GL and is currently 354 GL (52% capacity), and the flow to South Australia has averaged 55,800 ML/day.
At the Lower Lakes, all Barrage gates at Goolwa and Mundoo were closed for two days to minimise saline incursions during a large swell event over the weekend. This resulted in a rise in water level of 19 cm at the Goolwa Barrage gauge but a much smaller rise in the average level across all Lower Lakes gauges. The level has since declined slightly after the gates were re-opened. At Tauwitchere and Ewe Island Barrages, 137 gates remain open to enable the passage of the current high inflows that continue at the Lower Lakes.
The 5 day average level for the lakes is 0.76 m AHD or 1 cm above full supply. Renewed high tides with levels up to 1.46 m are forecast for the coming week. To prevent short periods of reverse flow, the gates at Goolwa and Mundoo will be closed for much of the coming week. High water levels in the Lower Lakes are therefore expected by week’s end. These operations are being adaptively managed, for although tide heights can be reasonably well predicted in advance, the impact of winds and swells on tidal surge are more difficult to predict.