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 the State’s 20 urban and rural water corporations.

Rainfall

Dry, warm and windy weather conditions resulted in a decrease in flows in most Victorian rivers and streams during September. West Gippsland and Victoria’s south-west coast recorded rainfall totals close to average; however the rest of Victoria recorded rainfall less than half the long-term average. Melbourne received just 18.6 mm of rain during the month, which is well below the long-term September average of 53.0 mm. Mean daily maximum temperatures were between 1 to 2 degrees above normal across the State, whilst minimum temperatures were mostly about half a degree below normal.

Streamflows

Dry, warm and windy weather conditions resulted in flow deterioration in most Victorian rivers and streams during September. At the end of the month, rivers and streams located across most of northern, western, central and far-eastern Victoria were recording flows of less than 10% of the long-term average for September. The Macalister River at Glencairn was recording the highest flows of 73% of the long-term average for September.

Storage Levels

With the exception of the Glenelg/Wimmera Basin, storage volumes tended to increase or remain relatively steady in all of Victoria’s major basins during the month. Volumes in the major storages throughout the State increased by 0.8% in September to be at 26.8% of capacity. Melbourne Water's storages increased by 1.1% in September 2007 to finish the month at 39.8% of capacity, whilst Rural Water Authority storages increased by 0.8% to finish the month at 24.5% of capacity. Storages in the Glenelg-Wimmera Basin dropped to 8.0% of capacity, Lake Eildon rose to 22.9% of capacity and Rosslynne Reservoir decreased slightly to 5.0% of capacity.

Urban Water Restrictions

A number of key changes to towns on restrictions took effect during September 2007. Restrictions were lifted or reduced for a number of towns in south Gippsland and north-east Victoria. Lower Murray Water introduced general exemptions to Stage 4 Water Restrictions for its customers. The total number of Victorian towns on restriction as at 30 September was 375, of which 24 towns are on Stage 1, 86 are on Stage 2, 12 are on Stage 3, 18 are on Stage 3a, 14 are on Stage 4 with general exemptions and 221 are on Stage 4.

Irrigation Allocations

G-MW made its latest allocation announcement for the 2007/2008 season on 1 October. The Goulburn allocation was increased to 23% and the season extended to 30 April 2008. The Murray allocation was increased to 16% with a season close date of 15 March 2008. Allocations were announced on both the Loddon (5%) and Broken (15%) systems with a season close date of October 31. However, delivery restrictions on both systems were lifted in the latest announcement to allow diversions throughout the season. Access after 31 October will be rostered to minimise system losses. The Campaspe system has been given a 1% allocation. All orders will be rostered to minimise system losses. Allocations in the Bullarook Creek system remain zero. Coliban Water’s rural season opened at 30% of licensed volume.

SRW opened the 2007/08 irrigation season in the Macalister Irrigation District on 15 August with an allocation of 100%. Recent dry conditions saw off-quota water finish in early September. In the south-east, licence holders downstream of Blue Rock are currently able to pump from unregulated flows. A formal allocation for the season will be announced once unregulated flows drop away. SRW has announced an allocation of 5% water right and 100% domestic and stock for the Werribee and Bacchus Marsh irrigation districts. Rights to water in the Deutgam Groundwater Management Area remain suspended to protect the resource from seawater intrusion.

Restrictions on Diversions

Changes in restrictions on unregulated streams in Victoria during September generally reflected the diminishing streamflows throughout the State. At the end of September, diversions from a total of 112 streams and lakes across the State were subject to some form of restriction.

Seasonal Climate Outlook

The Bureau of Meteorology’s rainfall outlook for the December quarter shows a moderate shift in odds favouring a drier than normal season in south-eastern Australia. With the exception of the Southern Oscillation Index (SOI), all ENSO indicators showed an intensifying La Niña during September. However, this La Niña is late to develop by historical standards. Widespread rainfall over Australia’s eastern half is not as likely to occur under late developing La Niña events. Moreover, Australia’s climate may continue to be influenced by the unusual cooling of the oceans to the north of the continent. The current pattern is inhibiting the formation of northwest cloud bands, which are the major source of winter and spring rain in central and south-eastern Australia during La Niña years.