Shoalhaven Scheme

Tallowa Dam
The Tallowa Dam spillway, 2010.
Status	Operational
Dam and spillways
Spillway type	Central overflow
Spillway capacity	27,600 cubic metres per second (970,000 cu ft/s)
Website Tallowa Dam at www.sca.nsw.gov.au

Fitzroy Falls Dam
The Fitzroy Falls Reservoir, 2010
Status	Operational
Dam and spillways
Spillway capacity	516 cubic metres per second (18,200 cu ft/s)
Website Fitzroy Falls Reservoir at www.sca.nsw.gov.au

Wingecarribee Dam
The Wingecarribee Dam wall and reservoir, 2010
Status	Operational
Dam and spillways
Spillway capacity	520 cubic metres per second (18,000 cu ft/s)
Website Wingecarribee Reservoir 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

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

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

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

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

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

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

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

• List of reservoirs and dams in Australia

References

Additional reading

• 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.