Shoalhaven Scheme

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Tallowa Dam
TallowaDam Discharge2.JPG
The Tallowa Dam spillway, 2010.
Status Operational
Opening date 1976
Dam and spillways
Type of dam Gravity dam
Impounds Shoalhaven River
Height 43 metres (141 ft)
Length 518 metres (1,699 ft)
Dam volume 325 cubic metres (11,500 cu ft)
Spillways 1
Spillway type Central overflow
Spillway capacity 27,600 cubic metres per second (970,000 cu ft/s)
Reservoir
Creates Lake Yarrunga
Total capacity 85,500 megalitres (3,020×10^6 cu ft)
Catchment area 5,750 square kilometres (2,220 sq mi)
Surface area 831 hectares (2,050 acres)
Website
Tallowa Dam at www.sca.nsw.gov.au
Fitzroy Falls Dam
FitzroyFallsReservoir.JPG
The Fitzroy Falls Reservoir, 2010
Status Operational
Opening date 1974
Dam and spillways
Type of dam Embankment dam
Impounds Yarrunga Creek
Height 14 metres (46 ft)
Length 1,530 metres (5,020 ft)
Dam volume 760 cubic metres (27,000 cu ft)
Spillway capacity 516 cubic metres per second (18,200 cu ft/s)
Reservoir
Creates Fitzroy Falls Reservoir
Total capacity 23,500 megalitres (830×10^6 cu ft)
Catchment area 31 square kilometres (12 sq mi)
Surface area 522 hectares (1,290 acres)
Website
Fitzroy Falls Reservoir at www.sca.nsw.gov.au
Wingecarribee Dam
WingecarribeeReservoir.JPG
The Wingecarribee Dam wall and reservoir, 2010
Status Operational
Opening date 1974
Dam and spillways
Type of dam Embankment dam
Impounds Wingecarribee River
Height 19 metres (62 ft)
Length 1,140 metres (3,740 ft)
Dam volume 573 cubic metres (20,200 cu ft)
Spillway capacity 520 cubic metres per second (18,000 cu ft/s)
Reservoir
Creates Wingecarribee Reservoir
Total capacity 25,875 megalitres (913.8×10^6 cu ft)
Catchment area 40 square kilometres (15 sq mi)
Surface area 625 hectares (1,540 acres)
Website
Wingecarribee Reservoir at www.sca.nsw.gov.au
Bendeela Pondage
Status Operational
Opening date 1972
Dam and spillways
Type of dam Embankment dam
Impounds Kangaroo River
Height 15 metres (49 ft)
Length 2,118 metres (6,949 ft)
Spillways 1
Spillway type Weir-type
Reservoir
Total capacity 1,200 megalitres (42×10^6 cu ft)
Catchment area 20 hectares (49 acres)
Surface area 20 hectares (49 acres)
Website
Bendeela Pondage at www.sca.nsw.gov.au

The Shoalhaven Scheme is a dual-purpose water supply and hydro-electric power generation scheme located on the South Coast region of New South Wales, Australia.

The Scheme was built as a joint project between the Electricity Commission of NSW and the NSW Metropolitan Water Sewerage and Drainage Board. Management has subsequently passed to Eraring Energy and the Sydney Catchment Authority.

Water supply[edit]

Water in the scheme is stored in three principal dams and their associated reservoirs: Tallowa Dam, Fitzroy Falls Dam and Wingecarribee Dam. Wingecarribee River is a tributary of Warragamba River, so water pumped into Wingecarribee Reservoir can be released into Warragamba Dam and hence the Sydney water supply. Water can also be released into Nepean Dam via a system of rock cuttings and tunnels known as Glenquarry Cut. Water from the Nepean Dam can be transferred to Sydney, or to Wollongong via Avon Dam.

Tallowa Dam[edit]

Tallowa Dam, completed in 1976, is a concrete gravity dam with central overflow spillway, located of the Shoalhaven River, downstream from the river's confluence with the Kangaroo River. The dam wall of 325 cubic metres (11,500 cu ft) is 43 metres (141 ft) high and 528 metres (1,732 ft) in length. At 100% capacity, the dam wall holds back approximately 85,500 megalitres (3,020×10^6 cu ft) and creates the impounded reservoir of Lake Yarrunga that has a surface area of 831 hectares (2,050 acres), drawn from a catchment area of 5,750 square kilometres (2,220 sq mi). The spillway has a discharge capacity of 27,600 cubic metres per second (970,000 cu ft/s).[1]

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 approximately 90,000 megalitres (3,200×10^6 cu ft) but only 7,500 megalitres (260×10^6 cu ft) is available to be transferred to the Sydney water supply. 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.[2]

Fitzroy Falls Dam[edit]

Fitzroy Falls Dam, completed in 1974, consists of four separate earth and rockfill embankments, is located on the Yarrunga Creek upstream of Fitzroy Falls and about 16 kilometres (9.9 mi) southeast of Moss Vale. The main embankment of 760 cubic metres (27,000 cu ft) is 14 metres (46 ft) high and 1,530 metres (5,020 ft) in length. At 100% capacity, the dam wall holds back approximately 23,500 megalitres (830×10^6 cu ft) and creates the impounded reservoir of Fitzroy Falls Reservoir that has a surface area of 522 hectares (1,290 acres), drawn from a catchment area of 31 square kilometres (12 sq mi). The spillway has a discharge capacity of 516 cubic metres per second (18,200 cu ft/s).[1][3]

The 3,030 metres (9,940 ft) Wildes Meadow Canal connects the reservoir to the Burrawang Pumping Station. The 2,830 metres (9,280 ft) Burrawang Tunnel and 1,000 metres (3,300 ft) Canal join the pumping station to the Wingecarribee Reservoir.[4]

Wingecarribee Dam[edit]

Wingecarribee Dam, completed in 1974, is an earth and rockfill embankment dam structure located on the Wingecarribee River about 15 kilometres (9.3 mi) southeast of Bowral. The embankment of 573 cubic metres (20,200 cu ft) is 19 metres (62 ft) high and 1,140 metres (3,740 ft) in length. At 100% capacity, the dam wall holds back approximately 25,875 megalitres (913.8×10^6 cu ft) and creates the impounded reservoir of Wingecarribee Reservoir that has a surface area of 625 hectares (1,540 acres), drawn from a catchment area of 40 square kilometres (15 sq mi). The spillway has a discharge capacity of 520 cubic metres per second (18,000 cu ft/s).[1] Wingecarribee Reservoir lost around 9,000 megalitres (320×10^6 cu ft) of storage capacity as a result of the inflow of peat from the Wingecarribee Swamp collapse in August 1998. The original storage capacity was 34,500 megalitres (1,220×10^6 cu ft).[5]

Bendeela Pondage[edit]

Bendeela Pondage, completed in 1972, is an earth and rockfill embankment dam structure located on the Kangaroo River arm of Lake Yarrunga, is located between Fitzroy Falls Dam and Tallowa Dam. The pondage functions as a buffer storage for out-of-balance flow between the two dams during hydro-electric power generation or water pumping at Kangaroo Valley and Bendeela pumping and power stations. The dam has no significant catchment but has been provided with a weir type spillway to protect the dam in the event of operational problems at the two pumping and power stations. The embankment is 15 metres (49 ft) high and 2,118 metres (6,949 ft) in length. At 100% capacity, the dam wall holds back approximately 1,200 megalitres (42×10^6 cu ft).[6]

A 740 metres (2,430 ft) pipeline connects Bendeela Pumping and Power Station with Bendeela Pondage. Some 3,680 millimetres (145 in) in diameter, the pipeline is capable of handling water capacity of 205 megalitres (7.2×10^6 cu ft) per hour.[4]

Power generation[edit]

In addition to its water supply capabilities which supplements water supplies to the Sydney area, the Shoalhaven Scheme also comprises two hydro-power facilities, with total generating capacity of 240 megawatts (320,000 hp). The flexibility of the scheme is that it can operate as either a pump or a generator. During off peak periods, it utilises excess electricity from the grid to pump water back up to the reservoir(s) as pumped storage. The two power stations are:[7][8]

  • Kangaroo Valley Power Station in the Kangaroo Valley has two 80 megawatts (110,000 hp) pump turbines, for a total electricity generating capacity of 160 megawatts (210,000 hp). From Bendeela Pondage, Kangaroo Valley Pumping and Power Station lifts water a further 480 metres (1,570 ft) to Fitzroy Falls Reservoir via a tunnel, shaft, pipeline, and canal. Water available for hydro-electric power generation is discharged back down the conduits, driving turbines as it returns to Bendeela Pondage and then Lake Yarrunga.
  • Bendeela Power Station has two 40 megawatts (54,000 hp) pump turbines, for a total of 80 megawatts (110,000 hp) of electricity generating capacity. Bendeela Pumping and Power Station is located on the Kangaroo River arm of Lake Yarrunga, lifts water 127 metres (417 ft) to Bendeela Pondage.

The power stations were completed in 1977 as a joint project between the Electricity Commission of New South Wales and the NSW Metropolitan Water Sewerage and Drainage Board. Management has subsequently been passed from those bodies to Eraring Energy and the Sydney Catchment Authority.[7]

Environmental consequences[edit]

The Shoalhaven River and its main tributary the Kangaroo River. Tallowa Dam has been a barrier to migratory native fish with estuarine/marine juvenile stages, blocking species including Australian bass from more than 80% of their former range in the Shoalhaven system. Stockings of hatchery bred Bass in Lake Yarrunga has been an attempt to remediate the situation.[citation needed] A fishway for Tallowa Dam has been discussed for more than 20 years but is yet to eventuate.[citation needed] Lake Yarrunga also contains exotic species such as carp, which are now present in high densities. A fish lift began operation in August 2009.[9]

See also[edit]

References[edit]

  1. ^ a b c "Register of Large Dams in Australia" (Excel (requires download)). Dams information. The Australian National Committee on Large Dams Incorporated. 2010. Retrieved 3 May 2013. 
  2. ^ "Tallowa Dam". Water storage and supply report. Sydney Catchment Authority. Retrieved 9 March 2013. 
  3. ^ "Fitzroy Falls Reservoir". Water storage and supply report. Sydney Catchment Authority. Retrieved 9 March 2013. 
  4. ^ a b "Dams of Greater Sydney and surrounds: Shoalhaven" (PDF). Sydney Catchment Authority. April 2012. ISBN 1-876951-12-5. Retrieved 4 May 2013. 
  5. ^ "Wingecarribee Reservoir". Water storage and supply report. Sydney Catchment Authority. Retrieved 9 March 2013. 
  6. ^ "Bendeela Pondage". Sydney Catchment Authority. Retrieved 23 March 2013. 
  7. ^ a b "Shoalhaven". Generation Portfolio: Hydro Power Stations. Eraring Energy. 2 May 2013. Retrieved 4 May 2013. 
  8. ^ "Hydro electric power generation". Water supply: Major SCA dams: Shoalhaven system. Sydney Catchment Authority. 31 May 2011. Retrieved 4 May 2013. 
  9. ^ Woodford, James (24 August 2009). "What's scaly and goes up and down? A fish in an elevator". The Sydney Morning Herald. Retrieved 9 March 2013. 

Additional reading[edit]

  • Gehrke, P. C.; Gilligan, D. M.; Barwick, M. (2002). "Changes in fish communities of the Shoalhaven River 20 years after construction of Tallowa Dam, Australia". River Research and Applications 18: 265–286.