Water Week

EWN Publishing

Murray Darling Report 26 September: Failure of winter and spring rainfall

Posted by waterweek on 4 October 2007

The failure of winter and spring rainfall was a disaster for the Murray Darling Basin, after successive years of drought. Water to Adelaide was so salted as to be of little value, and over 300 towns had no water, or severe water restrictions. Flow was down to 800 ML/day to Adelaide. “Very high salinities of around 13 000 EC continue to be recorded in the Goolwa channel upstream of the Goolwa Barrage”. David Dreverman General Manager of Murray river systems, in the Report For The Week Ending Wednesday, 26 September 2007, published 28 September, 2007 he said “very little rain fell over the Basin this past week, with the highest falls being in South Australia.

River Murray continues decline: Along the Lower Murray there was 17 mm at Tailem Bend and 9 mm at Waikerie. Due to dry conditions in the catchment area, inflows to the River Murray System continue to gradually decline”.

River Operations: Release from Dartmouth remains steady at 200 ML/day and the storage volume has increased from 656 to 664 ML/day (17 per cent of capacity).

Snowy releases increase flows: Hume storage also continues to slowly rise primarily due to release from the Snowy Mountains Scheme via Murray 1 power station – and has increased from 844 to 857 GL (28.2 per cent of capacity)., Release from Hume reservoir has been increased to 2500 ML/day to target a flow of 4000 ML/day at Albury/Wodonga. This rise will meet increasing downstream needs and will allow a further small rise in the level of Lake Mulwala.

Lake Mulwala storage: Lake Mulwala has been raised from 123.7 to 123.8 m AHD over the past week and will reach about 124 m AHD by early October. It is expected that levels will remain at about this level over coming weeks but will be subject to changes in weather and demand conditions. Release from Lake Mulwala has been increased from 2600 to 3000 ML/day in order to boost declining river flows further downstream.

Torrumbarry Weir storage: Torrumbarry Weir pool is being used as a mid river storage and is currently being drawn upon to increase flows downstream until the higher flows from Lake Mulwala arrive next week. This has resulted in a temporary lowering of the weir pool from 86.05 to 85.9 m AHD. Euston Weir storage: Release from Euston Weir averaged 1840 ML/day this week but is expected to increase to around 2000 ML/day within the next few days as the higher flows from Torrumbarry Weir arrive.

Euston Weir pool cut from Murray: Beginning 1 October, the Euston Weir pool will be further lowered by around 3 – 5 cm/week in order to reduce evaporative losses along the river.

Lake Victoria is now closed: The inlet to Lake Victoria is now closed ensuring that adequate flow and weir pool levels are maintained in the River Murray at Locks 9, 8 and 7. Release from Lake Victoria has been increased from 1400 to 1600 ML/day and storage has fallen from 552 GL to 542 GL (80 per cent of capacity).

Flow to South Australia: Flow to South Australia averaged around 1900 ML/day and although the flow at Lock 1 temporarily increased to 1 500 ML/day it has since fallen back to 800 ML/day, Salinity rises at Morgan: Salinity levels at Morgan and Lock 1 have increased by about 50 EC this week and are currently 780 and 690 EC respectively. The level of the Lower Lakes has fallen from 0.25 to 0.18 m AHD since mid August with Milang Jetty showing an increase in salinity of around 350 EC to the current level of about 2350 EC.

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