Small Allocations Increases for Murray and Goulburn Systems on 15 October

Determination Data

Seasonal determinations for northern Victoria regulated river systems.

Further Information

Goulburn-Murray Water (G-MW) today announced increased seasonal allocations in the Murray and Goulburn systems. The Murray system seasonal allocation is now 17% of high-reliability water shares (HRWS) and the Goulburn system allocation is 12% HRWS. The seasonal allocations for all other northern Victorian water systems remain at zero.

"The monthly inflows to 15 October have been exceptionally poor across northern Victoria," said G-MW Managing Director David Stewart. "Historically, rainfall during October has provided beneficial inflows to all of the water systems. This year, there has been very little rain and the inflows are just not there."

Mr Stewart continued, "Cautious system operations and minor inflows have provided the improvements in the Murray and Goulburn systems announced today. The Broken, Campaspe, Loddon and Bullarook systems already have severely restricted operations, but inflows are needed to produce allocations."

Supply in the Northern Victorian Systems

Delivery efficiency remains the objective for the Murray and Goulburn systems, despite the increased allocations. "The availability of water resources for allocation in these systems at this time is lower than in any previous season," said Mr Stewart.

The provision of qualified essential needs to customers is the priority for operations in the Broken, Campaspe, Loddon and Bullarook systems.

Customers in the Broken system can now have carryover water delivered until the end of November, with advice on further extensions to be provided in the next allocation update on 3 November.

Opportunities to deliver carryover in the Campaspe and Loddon systems are limited. Customers in these systems should discuss their delivery requirements with their Diversion Inspector.

Outlook for the Coming Months

The lack of inflows during late September and October has adversely affected the seasonal allocation outlook for the 2008/09 season. The outlooks for the Murray and Goulburn systems, which are based on current inflow conditions and monthly inflow statistics from seasons with low inflows during spring, are presented below.

The following terminology is used in the tables:

            ‘Wet'               - Inflow volumes that have 1 chance in 10 of being exceeded

            ‘Average'         - Inflow volumes that have 5 chances in 10 of being exceeded

            ‘Dry'                - Inflow volumes that have 9 chances in 10 of being exceeded

Murray System (%HRWS at Date Shown)

Goulburn System (%HRWS at Date Shown)

The expected 1 December 2008 seasonal allocations under a repeat of 2007/08 inflow conditions are 20% HRWS in the Murray system and 23% HRWS in the Goulburn system. October 2007 rainfall totals were below average across northern Victoria, and totals during November 2007 were mostly above average.

"Statistics based on historical inflows have limited value for allocation outlooks over relatively short outlook periods, such as to 1 December 2008," said Mr Stewart. "The very low rainfall totals up to 15 October 2008 means that the catchments are very dry. Heavy and persistent rainfall is needed to produce the inflows required to achieve allocations indicated by the ‘average' and ‘wet' inflow conditions presented in the outlook tables. The short term rainfall forecasts released by the Bureau of Meteorology for the next eight days indicate an absence of significant rainfall, and hence allocations indicated by the ‘dry' outlook are more likely."

Mr Stewart said, "As we move beyond the traditional period of highest inflows, future outlooks provided by G-MW will be based on appropriate historical inflow sequences and not the statistical approach used up until now."

Using current inflow trends and historical data, the possible range of allocations on 15 February 2009 are:

• 17% to 46% HRWS in the Murray system
• 12% to 38% HRWS in the Goulburn system

Without any significant rainfall events to produce unseasonal inflows, there is unlikely to be any allocations in the Broken, Campaspe, Loddon, or Bullarook systems this season.