Melbourne Water

Weekly Water Report

12 March 2010

Storage gain below expectations

Seasonal factors stifled runoff from recent storms, with under 3 billion litres added to Melbourne’s storages on the back of heavy rain.

The major catchments received an average of 65.3mm (427% above normal). This delivered a net increase of 2.7 billion litres to reservoirs in four days.

Though well above average for March, the amount of water flowing into the major reservoirs was limited by the relatively dry soils in the catchments.

By comparison, a similar amount of rain over four days in October 2009 delivered a net storage increase of 15 billion litres – 5 times more than this week’s storms.

This contrast shows how rain when the catchments are already wet (especially in winter and spring) delivers much more than isolated downpours in warmer months.

Storages are now 34.7% (628.9 billion litres) full, compared with 30.2% (536.0 billion litres) at the same time last year – a difference of more than 92.9 billion litres.

The wet weather helped keep residential water use low, with Melburnians using 133 litres each a day.

More information on restrictions and tips on how to reach the target are available from Target 155 or by contacting the government water retailers.

Stage 3a restrictions and Target 155 are currently in place.

Daily residential water use for Melbourne

   PREVIOUS WEEKS
   CURRENT WEEK
   TARGET 155

All figures include non-metropolitan supply for Western Water (supplied since March 2000), which are not included in annual Melbourne metropolitan consumption figures.

Melbourne's water storages

View interactive storage graph for 1997-2010 (opens in a new window)

   2007-08     2008-09     2009-10  
100% capacity = 1810.5 GL
NB: Prior to 26 June 2009, 100% capacity = 1773 GL

Total system storage (as of 11 March 2010)

Reservoir	Capacity at full supply (ML)	Current Volume (ML)	% Full
Thomson	1,068,000	228,535	21.4%
Cardinia	287,000	99,982	34.8%
Upper Yarra	200,000	133,358	66.7%
Sugarloaf	96,000	59,502	62.0%
Silvan	40,000	36,406	91.0%
Tarago	37,500	21,909	58.4%
Yan Yean	30,000	8,936	29.8%
Greenvale	27,000	19,082	70.7%
Maroondah	22,000	18,535	84.3%
O'Shannassy	3,000	2,631	87.7%
Total	1,810,500	628,876	34.7%

Rainfall recorded at the reservoirs

Catchment	5 Mar - 11 Mar 2010	Average for the period*	Variation	5 Mar - 11 Mar 2009
Thomson	62 mm	13.1 mm	373.3% above	6 mm
Upper Yarra	72.2 mm	11.4 mm	533.3% above	6.4 mm
O'Shannassy	66 mm	14 mm	371.4% above	16.8 mm
Maroondah	57.4 mm	10.9 mm	426.6% above	14.2 mm

* Average (30 year mean 1980-2009)

Stream flow for the major catchments

Catchment	5 Mar - 11 Mar 2010	Average for the period*	Variation	5 Mar - 11 Mar 2009
Thomson	2103 ML	980 ML	114.6% above	689 ML
Upper Yarra	858 ML	590 ML	45.4% above	161 ML
O'Shannassy	1375 ML	660 ML	108.3% above	552 ML
Maroondah	1037 ML	620 ML	67.3% above	457 ML
Total	5373 ML	2850 ML	88.5% above	1859 ML

* Average (30 year mean 1980-2009)

Note: These results are preliminary and are validated at the end of the month.

Yarra Catchment
Report for period 4 March - 10 March 2010 (inclusive):

• Current seven day rolling average flows for Yarra River @ Yarra Glen = 322.1 ML/day (up 99.1 ML/day from the previous week)
• Current seven day rolling average flows for Yarra River @ Warrandyte = 345.5 ML/day (up 138.0 ML/day from the previous week)
• Current seven day rolling average flows for Little Yarra River @ Yarra Junction = 38.6 ML/day (up 22.2 ML/day from the previous week)
• Current seven day rolling average flows for Woori Yallock Creek @ Yellingbo = 42.5 ML/day (up 26.6 ML/day from the previous week)
• Total rainfall at Upper Yarra Reservoir for March is 25.2 mm (long-term monthly average for March is 57.8 mm)
• Total rainfall at Silvan Reservoir for March is 77 mm (long-term monthly average for March is 58.6 mm)

Maribyrnong Catchment
Report for period 4 March - 10 March 2010 (inclusive):

Rosslyne Reservoir
Melbourne Water's Capacity Share of the storage as at 8 March 2010 was 33 Megalitres (ML)

• Current release from Rosslyne (as at 8 March 2010) to meet bulk entitlement demands = 0 ML/day
• Current seven day rolling average flows for Jacksons Creek @ Sunbury = 20.5 ML/day (up 20.5 ML/day from the previous week)
• Current seven day rolling average flows for Deep Creek @ Bulla = 196.7 ML/day (up 195.4 ML/day from the previous week)
• Current seven day rolling average flows for Maribyrnong River @ Keilor (Brimbank Park) = 163.7 ML/day (up 162.4 ML/day from the previous week)
• Total rainfall at Rosslyne Reservoir for March is 55.4 mm (long-term monthly average for March is 40.6 mm)

Note: Passing flows at Keilor, as per the bulk entitlement agreement, require 5.0 ML/day or natural, whichever is the lesser, to be passed at Keilor. Natural flows are based on flows at Deep Ck @ Bulla gauging station.

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