Bulk water storage and supply report - 20 July 2006

During the week approximately 30 millimetres of rainfall was recorded on the Shoalhaven Catchment, 25 millimetres on the Woronora and Blue Mountains catchments, 20 millimetres on the Upper Nepean Catchment and 15 millimetres on the Warragamba Catchment.

As at 3 p.m. Thursday, 20 July 2006, the inflow rate to Warragamba Dam including Shoalhaven transfers was 850 megalitres per day and to Tallowa Dam was 1250 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.

14.7.06

16°C

3.0 mm

1 293 ML

1 071 500 ML

41.5%

Sat.

15.7.06

16°C

2.0 mm

1 247 ML

1 071 000 ML

41.4%

Sun.

16.7.06

16°C

6.0 mm

1 230 ML

1 070 500 ML

41.4%

Mon.

17.7.06

19°C

Nil

1 442 ML

1 070 000 ML

41.4%

Tue.

18.7.06

17°C

13.0 mm

1 258 ML

1 070 000 ML

41.4%

Wed.

19.7.06

15°C

25.0 mm

1 288 ML

1 071 500 ML

41.5%

Thu.

20.7.06

13°C

10.0 mm

1 325 ML

1 073 000 ML

41.5%

 

Total supply for the week

9 084 ML

Average daily supply during week

1 298 ML

Volume pumped from Shoalhaven for the week

2 800 ML

Net weekly storage change (megalitres)

- 240 ML

Net weekly storage change (percentage)

0.0%

 

Available Water Storage as at 20 July 2006

Storage

Full Operating Storage (ML)

Storage Level (m)

Available Storage (ML)

Available Storage (%)

Net Weekly Change (ML)

Cataract

94,300

- 10.97

27,620

29.3

-100

Cordeaux

93,640

- 8.85

41,150

43.9

-210

Avon

146,700

- 11.09

48,960

33.4

-500

Nepean

69,810

- 7.79

47,500

68.0

350

Woronora

71,790

- 20.13

21,290

29.7

-120

Warragamba

2,027,000

- 20.43

818,900

40.4

-3,850

Prospect

8,870

- 1.17

3,070

34.6

10

Wingecarribee

24,100

- 1.38

18,230

75.6

260

Fitzroy Falls

10,000

- 0.22

8,920

89.2

4,070

Tallowa*

35,300*

- 0.03

35,090*

99.4*

-210

Blue Mountains

2,790

 

2,060

73.8

60

Total

2,584,300

 

1,072,790

41.5

-240


*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.