Bulk water storage and supply report - 31 August 2006

During the week approximately 15 millimetres of rainfall was recorded on the Blue Mountains Catchment, 10 millimetres on the Shoalhaven Catchment and less than 10 millimetres on the Warragamba, Upper Nepean and Woronora catchments.

As at 3 p.m. 31 August 2006, the inflow rate to Warragamba Dam including Shoalhaven transfers was 580 megalitres per day and to Tallowa Dam was 320 megalitres per day.

 

Date

24 hours to 8 a.m.

As at 3 p.m.

Sydney Max. Temp.

Sydney Rainfall

Bulk Water Supply

Available Storage

% Storage

Fri.

25.8.06

19°C

0.4 mm

1 326 ML

1 063 000 ML

41.1%

Sat.

26.8.06

20°C

Nil

1 299 ML

1 062 500 ML

41.1%

Sun.

27.8.06

19°C

0.4 mm

1 366 ML

1 061 500 ML

41.1%

Mon.

28.8.06

19°C

0.6 mm

1 585 ML

1 060 500 ML

41.0%

Tue.

29.8.06

19°C

Nil

1 344 ML

1 060 000 ML

41.0%

Wed.

30.8.06

21°C

0.8 mm

1 279 ML

1 059 500 ML

41.0%

Thu.

31.8.06

20°C

4 mm

1 272 ML

1 059 000 ML

41.0%

 

Total supply for the week

9 470 ML

Average daily supply during week

1 353 ML

Volume pumped from Shoalhaven for the week

7 700 ML

Net weekly storage change (megalitres)

- 4 950 ML

Net weekly storage change (percentage)

- 0.2%

 


Available Water Storage as at 31 August 2006

Storage

Full Operating Storage (ML)

Storage Level (m)

Available Storage (ML)

Available Storage (%)

Net Weekly Change (ML)

Cataract

94,300

- 10.74

28,510

30.2

70

Cordeaux

93,640

- 8.81

41,320

44.1

20

Avon

146,700

- 11.65

45,040

30.7

-700

Nepean

69,810

- 4.66

55,820

80.0

2,530

Woronora

71,790

- 20.68

20,450

28.5

-150

Warragamba

2,027,000

- 20.58

812,480

40.1

-2,140

Prospect

8,870

- 1.04

3,700

41.7

0

Wingecarribee

24,100

- 1.43

18,030

74.8

-30

Fitzroy Falls

10,000

- 0.34

8,310

83.1

-640

Tallowa*

35,300*

- 1.68

22,840*

64.7*

-3,940

Blue Mountains

2,790

 

2,330

83.5

30

Total

2,584,300

 

1,058,830

41.0

-4,950


*NOTE: The "full operating storage" for Tallowa Dam refers only to the amount of water in the dam that is available to be transferred to Sydney and the Illawarra.  When full, the dam can hold 90,000 ML but only 35,300 ML is available to be transferred.

Other water from Tallowa Dam is provided to Shoalhaven City Council for supply to local communities.  Water is also released from the dam as environmental flows for the Shoalhaven River.

 

  ‘Expanded storage’ levels

On Saturday 15 April 2006, the SCA reached a major milestone in our deep-water storage projects when a water supply access point was created at the base of Warragamba Dam.

Combined, the deep storage projects at Warragamba and Nepean dams add around six months of water supply to the system for use in the present drought. They also add about 40 billion litres a year to the available supply. The SCA will complete the final stages of the projects between now and August this year.

The establishment of the new access point in the Warragamba Dam wall represents the major engineering milestone in these projects.  As a result, we can now report available storage against the volume of the expanded system.  All reports will now relate to the expanded system.

The Government’s Metropolitan Water Plan February 2006 Progress Report uses this expanded storage level to determine the trigger points for further drought management actions:

  • Around 40 per cent of the expanded supply system is the trigger for moving forward with the construction of borefields to access groundwater;
  • Around 30 per cent of the expanded supply system is the trigger for moving forward with the construction of a desalination plant.