Bulk water storage and supply report - 20 April 2006

During the week approximately 5 millimetres of rainfall was recorded on the Blue Mountains Catchment. The Warragamba, Shoalhaven, Woronora and Upper Nepean catchments recorded negligible rainfall during the week.

As at 3 p.m. Thursday 20 April 2006, the inflow rates to Warragamba Dam including Shoalhaven transfers was 80 megalitres per day and to Tallowa Dam was 45 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.

14.4.06

25°C

4.0 mm

1 523 ML

  958 500 ML

40.2%

Sat.

15.4.06

27°C

Nil

1 373 ML

  956 500 ML

40.1%

Sun.

16.4.06

23°C

Nil

1 473 ML

  954 500 ML

40.0%

Mon.

17.4.06

22°C

Nil

1 656 ML

  953 000 ML

40.0%

Tue.

18.4.06

24°C

Nil

1 379 ML

  951 000 ML

39.9%

Wed.

19.4.06

26°C

Nil

1 443 ML

  949 000 ML

39.8%

Thu.

20.4.06

33°C

Nil

1 583 ML

  947 000 ML

39.7%*

* See following section for an explanation of the revision of this figure to 44.3%

 

Total supply for the week

10 430 ML

Average daily supply during week

1 490 ML

Volume pumped from Shoalhaven for the week

0 ML

Net weekly storage change (megalitres)

-13 480 ML

Net weekly storage change (percentage)

-0.6%

 

Available Water Storage as at 20 April 2006

Storage

Full Operating Storage (ML)

Storage Level (m)

Available Storage (ML)

Available Storage (%)

Net Weekly Change (ML)

Cataract

94,300

- 9.40

34,100

36.2

-850

Cordeaux

93,640

- 6.90

50,240

53.7

-1,200

Avon

146,700

- 9.75

58,760

40.1

-980

Nepean

40,810

- 11.93

8,710

21.3

1,270

Woronora

71,790

- 18.74

23,520

32.8

-250

Warragamba

1,857,000

- 18.54

731,830

39.4

-9,620

Prospect

8,870

- 1.07

3,560

40.1

-120

Wingecarribee

24,100

- 2.47

13,950

57.9

-1,280

Fitzroy Falls

10,000

- 0.36

8,220

82.2

-210

Tallowa*

35,300*

- 3.21

12,140*

34.4*

-180

Blue Mountains

2,790

 

1,970

70.6

-60

Total

2,385,300

 

947,000

39.7

-13,480


*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 in the future will 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.