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

December 2006 was dry across the State. Most of Victoria received below average rainfall for December, with parts of the southwest and east of the state receiving very much below average rainfall.

Streamflows

Given the prolonged dry conditions, catchments across the State are very dry, and despite some heavy rainfalls towards the end of December, almost all streams showed a further deterioration in flows relative to the monthly average. At the end of December, eighty percent of the State had streamflows that were less than 10% of the long-term average flow for the month. Flows recorded at nearly two-thirds of the gauged stations are the minimum ever recorded during December.

Storage Levels

Volumes in the major storages in Victoria reduced further by 3.9% in December. Melbourne Water's storages reduced by 1.5% in December 2006, to finish the month at 40% of capacity (18.2% lower than at the same time last year).

Rural Water Authority storages decreased by 3.4%, to finish the month at 17.6% of capacity (31.5% lower than at the same time last year). Storages in the Glenelg-Wimmera Basin are at 4.7% of capacity compared with 9% at the same time last year. At the end of the month Lake Eildon was at 11.9% of capacity compared with 46.8% at the same time last year, and Rosslynne Reservoir was at 5.2% of capacity compared with 13.7% at the same time last year. Fires currently burning in the East of Victoria pose an ongoing threat to water supplies and water quality for towns reliant on drinking water from the surrounding catchments.

Urban Water Restrictions

A number of new or increased urban restrictions took effect during December 2006. Key changes include; Stage 1 restrictions were imposed for all towns serviced by Lower Murray Water. Stage 2 restrictions were imposed in the East Gippsland region for all towns on the Mitchell River system, Omeo system and Swifts Creek. Stage 4 restrictions were imposed for Hamilton, Tarrington, Cavendish, Dunkeld, and all towns in the greater Geelong area.

The total number of towns subject to water restrictions from 31 December 2006 was 438 (compared with 181 at the same time in 2005). 101 towns are currently on Stage 1, 119 on Stage 2, 29 on Stage 3, and 189 on Stage 4 restrictions.

Irrigation Allocations

Water allocations for the 2006/2007 season were updated by Goulburn-Murray Water on 15 December 2006. The scheduled end of the irrigation season remains at 15 April 2007, however the allocation has increased by 1% for Goulburn (24%) and Broken (66%) system irrigators, due to savings created by efficient operations and lower than planned releases from Goulburn Weir. Emergency drought pumping at the Waranga Basin is still required to support the current allocation.

There is still no allocation for irrigation entitlements in the Campaspe and Loddon systems. In the Murray system, the allocation remains at 95% of Water Right and Licensed Volume. In the Bullarook System, customers supplied from Newlyn Reservoir have an allocation of 36% and the customers supplied from Hepburns Lagoon still have an allocation of 0%.

South of the Divide, because of the low storage situation, irrigation allocations for the 2006/2007 season are very low. 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.

In the Latrobe system, Blue Rock Lake is at 74.2% 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 (which normally contribute some 70% of entitlements). Lake Glenmaggie, which supplies the Thomson-Macalister Irrigation District, dropped to 12.8% of capacity during December. Irrigators in the Northern, Eastern and Tinamba/Riverslea areas remain on a 45% allocation. The seasonal allocation for irrigators in the Nambrok-Denison area increased to 50%, due to an increase in water available from Thomson Dam. Rosslynne Reservoir is at 5.2% of capacity and the allocation for Southern Rural Water diverters is 5%.

Seasonal Climate Outlook

The Seasonal Outlook released by the Bureau of Meteorology on 20 December 2006 for January to March shows a moderate shift in the odds towards above-normal rainfall for southwest Victoria in the March quarter. Over the rest, and majority, of the State, the chances are between 45% and 60% for a wetter than normal quarter. Computer model guidance continues to suggest that the El Niño event may peak around January or February, which historically (but not consistently) has brought increased rainfall to Victoria.

However, there were signs that the El Niño event may have already started to weaken in late December, with Trade Winds in the western and central Pacific strengthening to near-normal values throughout December, sub-surface temperatures in the east-Pacific decreasing in warmth, and the Southern Oscillation Index only weakly negative for more than a month.