Monthly Water Report
Monthly Water Report
The Monthly Water Report provides a summary of the status of Victoria's water resources and water supplies at the end of the reporting month. It is based on validated water resource information provided by Victoria's 19 Urban and Rural Water Corporations and the Bureau of Meteorology. Each month's report is published online the following month. For detailed, specific and up-to-date information, please contact the relevant Water Corporation or the Bureau of Meteorology. Links to these organisations are located within the Monthly Water Report.
For a weekly snapshot you can now download the Department's Weekly Water Report on the Water Register website.
In June, rainfall was near average across most of Victoria and above average in the east. East and Central Gippsland generally experienced above average rainfall, with some areas receiving very much above average rainfall. The upper reaches of the Murray generally had above average rainfall, while western and central Victoria mostly had average rainfall. Heavy rainfall early in the month brought record daily totals for Chiltern (57.0 mm), Coleraine (37.0 mm), and the Gabo Island Lighthouse (93.2 mm), while the wettest station overall was 447.4 mm at Falls Creek. Statewide, the rainfall total was 31% above the June average.
Average rainfall in western Victoria during June did not lead to improved streamflows, with most western streams recording less than 40% of average flows at the end of June. The Werribee River at Ballan, Moorabool River at Batesford and Woady Yallock River at Cressy experienced very low flows of between 3% and 4% of the long term average. Moderate to high streamflows were recorded in the North East and Gippsland. Eight sites in the North East recorded June flows greater than 100% of the long term average. Tallangatta Creek at McCallums, Snowy Creek at Granite Flat and Rose River at Matong North all recorded flows above 180% of the long term average.
At the end of the month, flows at seven of the 28 representative stations were less than 10% of the long term average for June, with no flows (i.e. the rivers were dry) at three of these stations. Of the 25 representative stations which were flowing, all recorded higher flows than the historic June minimum.
The total volume of water held in Victoria's major storages increased by 4.7% during June, ending the month at 41.5% of capacity. There were slight decreases in storage (less than 1% change) in three of the 16 monitored basins, with increases in all others. The increases ranged from 0.8% in the Ballarat system to 16.1% in the Thomson/ Macalister system.
Victoria's regional storages increased by 5.4% to 38.4% of capacity during June 2016. Melbourne's storage levels increased by 0.6% to 59.4% of capacity over the same period. Melbourne's storages are 8.9% lower and the regional storages are 15.4% lower than at the same time last year.
Restrictions on urban water supplies
On 10 June, Barwon Water lifted the Stage 3 restrictions on its Lorne, Colac and Apollo Bay systems (14 towns). Later in the month, on 21 June, South Gippsland Water and Grampians Wimmera Mallee Water lifted Stage 2 restrictions on the Fish Creek (1 town), Korumburra (1 town), Little Bass (3 towns) and Eastern Grampians (4 towns) systems. At the end of June, no towns were on restrictions, compared to 23 towns at the end of May.
All Victorian towns are subject to Permanent Water Saving Rules.
There are a total of 37 Groundwater Management Areas (GMAs) and 16 Water Supply Protection Areas (WSPAs) in Victoria. These are both referred to as Groundwater Management Units (GMUs). There have been a number of GMU boundary changes over the last 6-12 months. These changes will be reflected in September 2016 when more boundaries have been confirmed.
At the end of the June quarter, the short-term (<5 years) groundwater level trends were not categorised as rising for any of the 16 WSPAs. The trend was declining in 12 WSPAs, and stable over the short term in the remaining four. Over the long term, nine WSPAs are categorised as stable and seven as being in decline.
The short-term trend is rising in two of 37 GMAs, declining in 20, and stable in 5. The remaining 10 GMAs do not have sufficient state observation bores for a short term trend to be determined. The trend for Frankston GMA moved from stable to rising, and Wa De Lock moved from rising to declining. The trend for four GMAs moved from stable to declining, and for one GMA the trend moved from rising to declining. The trend in six GMAs changed from stable to declining.
During June, the allocation status in all systems remained the same. The 2016/17 season opens on 1 July 2016.
Restrictions on diversions from unregulated streams
At the end of June 2016, there were 98 unregulated streams and lakes subject to diversion restrictions, compared to 123 at the end of May. This time last year, there were 94 waterways subject to restrictions.
Seasonal climate outlook
The Bureau of Meteorology (BoM) released its July to September 2016 rainfall outlook on 30 June 2016. The outlook has continued to improve, with most of the state having an increased chance of above median rainfall. It suggests northern Victoria is the most likely to have above median rainfall, with a 70-80% chance. The southern Wimmera, Central and Central Gippsland regions are predicted to have a roughly 55 to 65% chance of exceeding median rainfall, while the southern coastal areas have a roughly equal chance (45-55%). While above average rainfall forecast for parts of Victoria will be welcome, particularly in areas suffering from mid to long-term rainfall deficiencies, recovery is likely to require a significant period of above average rainfall.
BoM released its latest ENSO Wrap-Up on 21 June 2016. It announced that the tropical Pacific Ocean remains in a neutral El Niño–Southern Oscillation (ENSO) state- neither El Niño nor La Niña- with all ocean and atmospheric indicators now near normal.
Recent observations and climate model forecasts continue to suggest La Niña may develop in the coming months, hence the Bureau's ENSO Outlook remains at La Niña WATCH. A La Niña WATCH means there is a 50% likelihood of La Niña developing during the second half of 2016. If La Niña does develop, climate models suggest it is unlikely to reach levels seen in the most recent event of 2010–12, which was one of the strongest La Niña events on record. International models have weakened their outlook for La Niña compared to last month. While all models still indicate more cooling in the tropical Pacific Ocean is likely, only four of eight models now suggest La Niña could form in the second half of 2016. The other four models remain neutral.