The Monthly Water Report provides a statewide monthly summary of the status of water resources and water supplies. Each month's report is published online towards the end of the following month. It is based on data provided by Victoria's 19 urban and rural water corporations.

Rainfall

Victoria experienced a cool and wet December with total monthly rainfall equal to or above the long-term normal across the whole state. Total rainfall across much of western Victoria was very much above average.

Two rainfall recording sites in the south-west experienced their highest December rainfall on record. A further 14 sites recorded their highest December rainfall for 20 years.

Streamflows

At the end of the month, streamflows across southwest and eastern Victoria showed improvement due to above-average December rainfall.

Of the 28 representative gauging stations, 14 recorded flows greater than 10% of the long-term average for December and 14 recorded flows less than 10%.

The highest flow of 88% of the long-term December average was recorded on the Macalister River at Glencairn.

Storage Volumes

Widespread above-average rainfall across the state has slowed the rate of decline in storage levels, and led to some recovery in the southern storages.

At the end of December, the total volume in the state’s major storages was 20.4% of capacity. This is a decrease of 0.4% over the month. Melbourne's storages increased by 0.8% during the month to finish at 34.9% of capacity. This is 4.3% lower than at the same time last year. 

Regional water storages decreased by 0.5% to finish the month at 18.5% of capacity.

Restrictions on Urban Water Supplies

Goulburn Valley Water reduced restrictions for Broadford and Clonbinane to Stage 1 from 14 December 2008. Coliban Water reduced restrictions for its Goulburn and Murray towns to Stage 2 from 15 December 2008.

The total number of Victorian towns on restriction as at 31 December 2008 was 334, of which 68 towns were on Stage 1, 44 were on Stage 2, 31 were on Stage 3, 19 on Stage 3a, 77 on Stage 4 with general exemptions, and 95 on Stage 4. 

Approximately 140 towns were not on water restrictions and were subject to Permanent Water Saving Rules.

Irrigation Allocations

During December, G-MW increased allocations by 7% to 28% on the Murray system, and by 5% to 23% on the Goulburn system. Allocations remained at 0% on all other northern systems.

The allocation on both the Coliban Rural System and the Wimmera-Mallee irrigation supply system remained at zero per cent during December.

In southern Victoria, the seasonal allocation for the Werribee and Bacchus Marsh irrigation districts remained at 4% of high reliability water share.

The allocation for the Macalister Irrigation District increased to 95% during December. Rainfall during late November and early December led to Lake Glenmaggie spilling before 15 December 2008 (the end of the official spilling season), and the water used before this date became Spill Entitlement. The allocation for irrigators supplied from Blue Rock Lake was 23%.   

Restrictions on Unregulated Streams

At the end of December, diversions from a total of 134 unregulated streams and lakes across the state were subject to some form of restriction. This is similar to this time last year when 133 streams were on restriction.

Seasonal Climate Outlook

The rainfall outlook for the period January to March 2009 was released by the Bureau of Meteorology on 17 December 2008. The outlook shows no strong bias towards either wetter or drier conditions. The chances of exceeding the median rainfall are between 45% and 50% across most of the state, and between 50% and 55% in the far east. This means that the chances of being wetter than normal are about the same as the chances of being drier.

The ENSO Wrap-Up (issued on 23 December 2008) reveals that the equatorial Pacific Ocean has continued to cool. This raises the possibility of indicators reaching La Niña levels if the cooling persists, and the development of a La Niña cannot be ruled out. However, most climate models forecast neutral conditions for the first quarter of 2009.