Update of Seasonal Determinations for 2013/14

Announcement Date: 15 Aug 2013
Next Announcement Due: 2 Sep 2013

Determination Data

Seasonal determinations for northern Victoria regulated river systems.

  High Reliability Water Share Change to High Reliability Water Share Low Reliability Water Share Comments
Murray 57% +7% 0% Not declared
Broken 33% +33% 0% -
Goulburn 95% +23% 0% Not declared
Campaspe 100% -% 0% Not declared
Loddon 95% +23% 0% -
Bullarook Creek 0% -% 0% -

Further Information

The Resource Manager for northern Victorian regulated water systems today announced an update to the seasonal determinations for the 2013/14 season.

The Murray system seasonal determination is 57% of high-reliability water shares (HRWS), an increase of 7%. The seasonal determination in the Goulburn and Loddon systems has increased by 23% to be 95% HRWS. The Broken system seasonal determination is 33% HRWS.

The Campaspe and Bullarook system seasonal determinations are unchanged. The Campaspe system seasonal determination is 100% HRWS. The Bullarook system remains at zero.

"Inflows to northern Victorian storages have increased with persistent rainfall over the last fortnight," said Dr Mark Bailey, Resource Manager. "Inflows in the Campaspe and Bullarook systems have improved, but haven't been enough to change seasonal determinations. The benefits have been strongest in the Goulburn and Broken systems, as reflected in today's announcement."

Rainfall in the north-east catchments has also caused the volume in Lake Hume to rise to a point that the Murray-Darling Basin Authority has started pre-releasing water. "The pre-releases from Lake Hume are treated as a spill under Victorian water accounting rules," said Dr Bailey. "The volume of spill from Lake Hume during August will be confirmed in early September. The complex monthly accounting of State shares in the Murray storages prevents the volume of spill being determined earlier. Once confirmed, the appropriate volumes will be deducted from the spillable water accounts in the Murray system for the 15 September assessment.

"No spills have yet occurred from Lake Eildon in the Goulburn system or Lake Eppalock in the Campaspe system. The risk of spill is high for both storages, which are each holding about 80% of capacity and still filling," said Dr Bailey. "Pre-releases or physical spills from Lake Hume, Lake Eildon or Lake Eppalock prior to a declaration of a low risk of spill will reduce spillable water account volumes in their respective systems and allow all storage inflows to contribute to seasonal determinations increases."

Outlook for the 2013/14 Season
The full inflow record was used to assess seasonal determinations for a range of inflow scenarios. The scenarios for different inflow conditions have been produced using the following terminology:

Wet Inflow volumes that have 10 chances in 100 (or 1 chance in 10) of being exceeded
Average Inflow volumes that have 50 chances in 100 (or 5 chances in 10) of being exceeded
Dry Inflow volumes that have 90 chances in 100 (or 9 chances in 10) of being exceeded


The following table summarises possible seasonal determinations in the Murray system through the 2013/14 season.

Murray System Outlook for Seasonal Determination of High-Reliability Water Shares

Inflow Conditions

15 October 2013

16 December 2013

17 February 2014














Seasonal determinations in the Goulburn system are expected to reach 100% HRWS by 15 September 2013 under all three inflow scenarios

Broken system customers are expected to have 100% HRWS from mid October 2013 and 100% low-reliability water shares (LRWS) from mid December under all three inflow scenarios.

"Seasonal determinations against LRWS in the Murray, Goulburn and Loddon systems will depend on usage and the volume of inflows during winter and spring," said Dr Bailey. "The chances of LRWS seasonal determinations improve if inflows cause debits from spillable water accounts and water is used during periods of unregulated flows without release from storage."

Under average conditions, seasonal determinations against LRWS in the Campaspe system should commence in mid spring.

Trading Opportunities

The probability of spill in the Victorian Murray system is currently greater than 50%, as indicated by the pre-releases from Lake Hume. Therefore, trade into Victoria from New South Wales is limited to the volume of trade out of Victoria to New South Wales. The availability of trade from NSW into the Victorian Murray system will be recalculated on 10 September 2013, and the 10th or next business day of each month thereafter. This limit is part of trade controls announced in November 2012 to prevent trade impacting on new season allocations.

Customers participating in the water trading market are reminded that the Murray-Darling Basin Authority has relaxed the rule controlling allocation trade from upstream of the Barmah Choke to downstream users. The Murray-Darling Basin Authority will regularly review the ability to trade across the Barmah Choke and may lift the relaxation at any time during the season.

Upcoming Resource Manager Announcements

  • The next seasonal determination announcement will be released on Monday 2 September 2013.
  • An updated probability of spill in the Murray, Goulburn and Campaspe systems will be announced on Tuesday 10 September 2013.