Welcome to the last River Ops update for 2011. As in previous years, there will be no Weekly Report issued for the week ending 28 December 2011. The next report will cover the two week period ending 4 January 2012.
Don’t forget the full River Murray Weekly Report – including images, graphs and data on flow and salinity – on the MDBA website. The full report is available in pdf and doc formats.
One final note before the main event, the Murray-Darling Basin Authority and staff at the storages, weirs and barrages of the River Murray System wish all our readers a safe and happy festive season.
MDBA active storage decreased by 107 GL during the week to 7,223 GL (84% capacity). At Dartmouth Reservoir, the total storage increased by 6 GL to 2,941 GL, which is 76% capacity.
The release at Dartmouth was increased as planned during the week to pass a flow pulse with a peak of 2,500 ML/day at Colemans, while downstream at Tallandoon, the river reached a peak of around 3,100 ML/day. The release has now been decreased to 670 ML/day and will be further decreased to the normal minimum of 200 ML/day in the coming days. This flow pulsing is consistent with environmental management guidelines for the Mitta Mitta River downstream of the dam, and is undertaken as a pre-emptive action to manage water quality issues such as algal growth during warm weather.
At Hume Reservoir the storage volume is currently 2,631 GL (88%), which is a decrease of 62 GL. The release was increased in the last few days to meet downstream demand and is currently at 16,200 ML/day.
Downstream at Lake Mulwala, diversions have increased in the last few days, and combined with lower than forecast inflows have resulted in the pool level lowering slightly to 124.67 m AHD, or 3 cm below the target level of 124.7 m AHD. The pool level should rise back to the target over the next few days. The release at Yarrawonga Weir is currently 11,000 ML/day, which is the target release to continue supplying environmental entitlements that are maintaining over-bank flows to the Barmah-Millewa forest.
On the Edward River, diversions through the Edward and Gulpa offtakes remain steady. Downstream at Stevens Weir, diversion into the Wakool Main Canal has dropped back over the last few days, and flow past Stevens Weir has increased from 1,200 to 1,700 ML/day. Downstream on the Wakool River, the flow at Kyalite peaked at 3,500 ML/day during the week and has now receded to 3,200 ML/day. The flow should continue receding here over the coming week.
At McCoys Bridge, flow in the Goulburn River has receded from 3,600 to 1,800 ML/day during the week is now expected to continue to slowly recede to below 1,000 ML/day over the next few weeks depending on rain.
At Torrumbarry Weir, diversions at the National Channel were decreased to 1,150 ML/day following the rain. Releases from Torrumbarry Weir averaged 9,300 ML/day during the week and the release is expected to continue decreasing over the coming week.
On the Murrumbidgee River, the flow at Balranald increased as expected, with the current flow now at 5,000 ML/day. The river should rise further over the coming days. Downstream on the Murray, the flow at Euston eased early in the week, but has increased to 12,700 ML/day during the last few days. The flow is expected to increase further in the next few days.
At Menindee Lakes, the total storage decreased by 44 GL and the lakes are now below full supply – the first time they have been below full supply since March 2011. The lakes are currently holding 1,707 GL (99% capacity) and should continue to fall over the coming week as airspace is created ahead of floodwaters arriving from upstream during the coming weeks and months. The release measured at Weir 32 has been increased by the NSW Office of Water and State Water to 9,400 ML/day after they commenced flood operations last week. The release is now expected to reach 16,000 ML/day by 24 December, where it is forecast to remain over the Christmas-New Year period before rising further in early January. At this stage, the release will likely increase to around 24,000 ML/day during early to mid January 2012. For further information regarding flood operations at Menindee Lakes, please refer to information from the NSW Office of Water (http://www.water.nsw.gov.au/)
Storage in Lake Victoria decreased by 9 GL during the week to 618 GL, which is 91%. Heavy rainfall on and around Lake Victoria during the week reduced the rate of fall. The flow to South Australia is currently 15,000 ML/day, but will rise in the coming days to in excess of 20,000 ML/day by New Year.
The five day average level in the Lower Lakes increased 0.01 m to 0.64 m AHD and the flow out the Barrages continued to average around 4,500 ML/day for the week.