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

Rainfall totals for May were below average across most of the state.  By the end of the month, most of Victoria had only received between 40% and 80% of the long-term average rainfall for May.   The situation was slightly better in the north and west, with the Wimmera and Mallee districts receiving between 60% and 100%, and the Western district receiving up to 80%.  The situation in the east of the state was worse, with the East Gippsland district and a large part of the Northeast district receiving less than 40% of the long-term average rainfall for May. Two rainfall recording sites across the state experienced their lowest May rainfall for at least 20 years, and another two sites experienced their lowest May rainfall on record.

Streamflows

Despite higher rainfall than experienced in April, the stream flow situation across the state worsened during May. At the end of the month, stream flows were below average across the entire state.  Flows below 10% of the long term average for May were recorded at 15 of the 28 representative stations in central, north western and far east Victoria.

Storage Levels

Volumes in the state’s major storages declined to 17.9% during May, a decrease of 0.1% over the month.  The decline of storage volumes has slowed due to decreased demand and small storage inflows throughout May. The lowest storage volumes are in central and northern Victoria.  Melbourne's storages decreased by 1.4% during the month to finish at 30.1% of capacity, which is 1.3% higher than at the same time last year.  Rural water corporation storages increased by 0.2% to finish the month at 15.7% of capacity.

Urban Water Restrictions

The total number of Victorian towns on restriction as at 31 May 2008 was 366.  Of these, 63 towns were on Stage 1, 70 were on Stage 2, 41 were on Stage 3, 18 were on Stage 3a, 77 on Stage 4 with general exemptions, and 97 on Stage 4.  In northern Victoria, North East Water reduced restrictions to Stage 2 for 12 towns from 17 May, and lifted  restrictions for a further six towns from 30 May.

Irrigation Allocations 

Irrigation allocations were still extremely low across northern, central and western Victoria at the end of May.  In northern Victoria, G-MW announced the final seasonal allocations on 1 April, with water resource improvements received after this date until the end of June 2008 to be used for system operations and allocations during the 2008/09 season. The seasonal allocation for Coliban Water’s rural system remained at 35%, whilst the irrigation allocation remained at zero in the Wimmera-Mallee supply system.

In southern Victoria, allocations in the Werribee and Bacchus Marsh Irrigation District remained at 8% and Southern Rural Water continued the ban on access to groundwater in the Deutgam groundwater management area.  Storage levels in the Latrobe Valley’s Blue Rock Lake are higher than at the same time last year and there is enough water for the power stations, however the regulated irrigation allocation from Blue Rock Lake stood at just 17.3%. The irrigation season closed on the 15 May with allocations  at 200% for all irrigators within the Macalister Irrigation District (MID), and for diverters on the Thomson River, Macalister River and Rainbow Creek. 

Restrictions on Diversions 

At the end of May, diversions from a total of 168 unregulated streams and lakes across the state were subject to some form of restriction.  This is less than at the same time last year when 207 streams were on restriction.

Seasonal Climate Outlook

The latest rainfall outlook was released by the Bureau of Meteorology on 27 May 2008.  The outlook for the June – August period indicates that the chance of exceeding the three-month median rainfall is 50 to 55% across most of Victoria. 

The Bureau issued the latest ENSO Wrap-Up on 21 May.  The climate patterns in the Pacific remain generally neutral.   Computer models show Pacific temperatures continuing to gradually increase over the next two seasons, but remaining near-average (i.e. neutral conditions), with a low likelihood of either a stronger warming to El Nino levels or a re-intensification of La Nina conditions during 2008.