WHILE there was some welcome rainfall in early November, it was brief and produced little water improvement for NSW.
The Water Allocation Statement for November from the NSW government’s Department of Industry reports: “Of the 25,000 megalitre (ML) improvement, 15,000ML has been allocated to conveyance licences [the volume needed to maintain critical human water needs] and 4,000ML has been temporarily set aside in anticipation of excessive transmission losses over summer.
“The remaining 6,000ML was required for the River Murray Increased Flows (RMIF) commitment due to previously over-estimated RMIF usage. Remaining shortfalls in the NSW Murray system include 15,000ML to conveyance licences, and 60,000ML to environmental water. Of the environmental shortfall, 30,000ML is the outstanding commitment to RMIF and 30,000ML is expected to be needed to run the Wakool system after a hot summer.
“Consideration of high-priority commitments in 2019/20 must also begin to be applied to resource improvements. The outlook for all inflow scenarios is therefore that NSW Murray general security allocations are likely to remain low in 2018/19.”
The statement reports that allocations in the Lower Darling remain unchanged. The Menindee Lakes system is at 7% of full supply capacity and is critically low.
WaterNSW reports it is continuing to fill two temporary block banks in the Lower Darling for drought contingency to extend access for high-priority uses as long as possible. Approval to construct two extra block banks between Menindee and Pooncarie has been granted. This work will affect flows in the Lower Darling below construction sites.
The Water Allocation Statement continues: “In the past, as water availability deteriorated and cease-to-flow conditions commenced, water restrictions have been used to restrict the take of water from available pools to the highest priority uses including town water supply, domestic, stock, and permanent plantings. The current need for restrictions is constantly monitored.”
Murray storage levels (as at 14 November 2018)
● Dartmouth Dam is 78% full, and falling. Holding 3,003,000ML. NSW share of this water is 28%.
● Hume Dam is 45% full, and falling. Holding 1,354,000ML. NSW share is 39%.
● Lake Victoria is 76%, and rising. Holding 515,000ML. NSW share is 37%.
The monthly forecast to the end of October indicated 5,210 gigalitres (GL) of total Murray resource was available in the very dry case, of which 1,580GL was needed to run the system and therefore 3,630GL was distributed to NSW and Victoria based on rules in the Murray-Darling Basin Agreement. The NSW share of this was about 1,190GL from which commitments to South Australia’s entitlement flow and trade adjustments were deducted to leave NSW with 1,035GL of resource to distribute. This represented an increase of 25GL from the last assessment.
KEY: * Indicative breakdown of held environmental water holdings. ** Includes 1GL (100%) for high security subcategory. Source: NSW Department of Industry Water Allocations Statement November.
In the Murray, trade across the Barmah choke [a narrow stretch of the river in Victoria, which restricts water flow] remains restricted to ‘no net trade downstream’. Downstream trade opens to the extent of the volume of any upstream trade. The trade restriction helps to protect existing downstream entitlement holders from an increased risk of delivery shortfall due to the limited capacity of the Barmah choke.
Meanwhile, the Menindee Lakes system is below 480GL, the threshold at which the Lower Darling becomes administratively separated from the Murray. Temporary trade with the Murray is therefore closed. Trade typically remains closed until the system recovers to above 640GL. Trade within the Lower Darling water source remains unaffected.
Trade out and within the Murrumbidgee Valley is open, but trade into the Murrumbidgee Valley is closed. Trade into the Murrumbidgee Valley will re-open when the Murrumbidgee inter-valley trade account balance climbs to 15GL.
ALSO READ: The truth about the Murray-Darling: who's getting all the water?