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

The first three weeks of April saw the return of dry conditions to most of the State, with the exception being Gippsland, which continued to receive rain following good falls in March. The 22nd of April marked the start of significant rainfalls throughout the entire State, with good rainfalls in much of central and south-eastern Victoria. The weekend preceding the end of April saw significant rainfall in the Wimmera, Mallee and upper North-East districts, with falls in excess of 100mm recorded in a number of locations.

Overall, north-western Victoria enjoyed rainfall totals well above the long-term average for April. In contrast, rainfall in central Victoria, extending to southern Gippsland and the Otway Ranges, was below average. Rainfall totals across the rest of the State were close to average. Across Victoria, maximum temperatures were 1 degree to 2 degrees above average.

Streamflows

Given the prolonged dry conditions, catchments across the State are very dry, and despite reasonable rainfalls throughout April, the streamflow situation has shown only a small improvement. At the end of April, around 68% of the State had flows that were less than 10% of the monthly average for April. However just over 35% of reported streamflow stations around the State recorded zero flows, compared with 40% at the end of March.

Storage Levels

Volumes in the major storages in Victoria reduced by 1.6% in April. Melbourne Water's storages reduced by 2.0%, to finish the month at 30.0% of capacity (19.9% lower than at the same time last year). Rural Water Authority storages decreased by 1.5%, to finish the month at 9.0% of capacity (21.2% lower than at the same time last year). Storages in the Glenelg-Wimmera Basin were at 3.5% of capacity compared with 6.4% at the same time last year. At the end of the month, Lake Eildon was at 5.4% of capacity compared with 21.3% at the same time last year, and Rosslynne Reservoir remained steady at 4.3% of capacity compared with 8.5% at the same time last year.

Urban Water Restrictions

A number of new or increased urban restrictions took effect during April 2007. Key changes included the imposition of Stage 3a restrictions for all towns serviced by Melbourne Water and Western Water (excepting Lancefield). Goulburn Valley Water reduced restrictions at Longwood from Stage 4 to Stage 3; Central Highlands Water imposed Stage 1 restrictions for Clunes, Dean, Allendale, Broomfield, Kingston, Newlyn, Smeaton, Springmount, Learmonth and Waubra; and, Lower Murray Water increased restrictions from Stage 1 to Stage 2 from 30 April for all towns it supplies. The total number of towns subject to water restrictions as at 30 April 2007 was 455. Eighty-nine towns were on Stage 1, 49 on Stage 2, 56 on Stage 3, 18 on Stage 3a and 253 on Stage 4 restrictions.

Irrigation Allocations

Water allocations for the 2006/2007 irrigation season were updated by Goulburn-Murray Water on April 2 and 16 2007. The irrigation allocation was increased by 2% to 29% in the Goulburn system, whilst the allocation on the Broken was increased from 74% to 77%. There was no change in allocations for irrigators on the Campaspe, Loddon, Murray or Bullarook Systems. The season for all gravity irrigation system customers closed on 30 April 2007.

In the south-west of the State, allocations remain at 10% for the Bacchus Marsh and Werribee Irrigation Districts. Levels in the Deutgam Groundwater Management Area are low, and in order to protect the resource from seawater intrusion, allocations for the 2006/2007 season are at 25% of licensed volume. Rosslynne Reservoir is at 4.3% of capacity and the allocation for Southern Rural Water diverters remains at 5%.

Restrictions on Diversions

In the south-east of the State, on the Latrobe system, Blue Rock Lake is at 51.9% of capacity. SRW licence holders downstream are permitted to take up to their licence volume, but availability is likely to be limited by low unregulated river flows. Lake Glenmaggie, which supplies the Thomson-Macalister Irrigation District, increased to 8.1% of capacity during April. On 16 April, Southern Rural Water approved an increase of 5% in allocation for all customers in the MID and for Licensed Diverters on the Thomson and Macalister Rivers and Rainbow Creek. This increase was due to increased inflows into Glenmaggie Reservoir. Total allocation at 30 April was 55% of Licensed Volume, Water Right and Domestic and Stock for all MID customers and diverters.

Seasonal Climate Outlook

The Seasonal Outlook released by the Bureau of Meteorology on 23 April 2007, for the May to July period, continues to show near neutral odds across the State of exceeding the median rainfall. The chances of a warmer than average season have dropped to 35-40% across most of the State, increasing to 40-45% in the north and far east. Indications are that there is an elevated chance of a La Niña event occurring during 2007. Historically, La Niña events bring wetter than normal conditions across much of the eastern half of Australia from autumn onwards.