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 rainfall was above average in most parts of Victoria. This was largely due to a low-pressure system which crossed the state between 19 and 23 December. With the exception of the northern Mallee, most of northern Victoria received rainfall 50% - 100% above normal, with some areas between Bendigo and Kerang recording nearly double the long-term average for December. Central Victoria, including Melbourne, and parts of Western district also received 50% or more rainfall than normal. Melbourne received 71.4 mm of rain during the month, which is above the long-term December average of 58.1 mm. The average maximum temperature was 26.3°C. This is 2.7°C higher than the December average.

Streamflows

The rainfall at the end of the month resulted in good streamflows in many catchments and even some minor flooding in North Central Victoria. These inflows, although welcome, were not sufficient to recover the State’s major storages and have a large influence on the numbers of towns on restriction and irrigation allocations. By the end of the month, streamflows for half of the state were less than 10% of the long-term December average.

Storage Levels

Rural water corporation storages decreased by 0.5% to finish the month at 23.7% of capacity (6.1% higher than at the same time last year). Volumes in major northern storages increased slightly in all but the Murray Basin, whilst volumes in the Grampians Wimmera Mallee headworks storages declined. In the south, volumes in the major storages remained steady or declined in all but Blue Rock Lake, which continued to slowly increase. Melbourne's storages decreased by 0.8% in December to finish the month at 39.2% of capacity (0.2% higher than at the same time last year).

Urban Water Restrictions

378 Victorian towns were on restriction as at 31 December. 73 towns were on Stage 1, 57 were on Stage 2, 15 were on Stage 3, 18 were on Stage 3a, 103 on Stage 4 with general exemptions and 112 on Stage 4. There were a number of changes to urban water restrictions during the month. Barwon Water introduced Stage 2 restrictions for Apollo Bay, Skenes Creek and Marengo, whilst North East Water increased restrictions in Goorambat to Stage 2. In contrast, restrictions were reduced in Coongulla, Glenmaggie, Daylesford, Hepburn, Hepburn Springs, Lancefield and towns within Goulburn Valley Water’s Murray River system. North East Water also introduced exemptions to Stage 4 restrictions in Bundalong.

Irrigation Allocations

Although some systems recorded minor increases in irrigation allocations during the month, by the end of December allocations were still extremely low across northern, central and western Victoria. Allocations increased in the Goulburn, Murray and Broken systems, supported by system efficiency gains and modest inflows. The need for rostering of irrigation orders was removed on the Broken system, whilst customers in the Loddon and Campaspe systems continued to have rostered access only. There was not enough water in the Bullarook system for an irrigation allocation and irrigators remained on a qualified right to water for essential stock and domestic needs only. Coliban Water increased its rural seasonal allocation to 35% in December due to better than expected inflows in October and November and operational savings, whilst Southern Rural Water increased allocations in the Werribee and Bacchus Marsh irrigation districts from 5% to 8% as a result of a number of contingency actions and modest inflows to the system. Southern Rural Water’s ban on access to groundwater in the Deutgam Groundwater Management Area remained in place in December, whilst irrigation supplies remained at zero in the Wimmera Mallee supply system.

In contrast, irrigation allocations in south eastern Victoria are higher and the 2007/08 seasonal outlook more promising. Continuing inflows to Lake Glenmaggie enabled Southern Rural Water to announce a 105% allocation by the end of December. This allocation is in addition to the 46,000 ML, equivalent to 32% of water right volume, delivered during the off-quota period up to 20 November. River licence holders on the Latrobe River downstream of Blue Rock reservoir continued to pump from unregulated flows during the month. A formal allocation of irrigators’ share of water in Blue Rock reservoir will be announced for the Latrobe system once unregulated flows drop away.

Restrictions on Diversions 

At the end of December, diversions from a total of 133 unregulated streams and lakes across the State were subject to some form of restriction. This is significantly less than at the same time last year when 185 streams were on restriction.

Seasonal Climate Outlook

The Bureau of Meteorology released the latest rainfall outlook on 17 December. The outlook for the January to March quarter indicates that the chances of exceeding the three-month median rainfall are between 40 and 45% across western and central Victoria, increasing to 60% in the State’s east. A La Niña event is firmly established in the Pacific, strengthening over the past month and contributing to the enhanced eastern Australian rainfall since November. Although some computer models suggest that the event is nearing its peak, most continue to indicate the persistence of cool Pacific Ocean temperatures, consistent with a La Niña, until at least autumn 2008.