Tallowa Dam, completed in 1976, is a concrete gravity dam with central overflow

spillway A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure tha ...

, located on the

Shoalhaven River The Shoalhaven River is a perennial stream, perennial river that rises from the Southern Tablelands and flows into an open mature wind wave, wave dominated estuary#Lagoon-type or bar-built, barrier estuary near Nowra on the South Coast, New Sou ...

, downstream from the river's

confluence In geography, a confluence (also ''conflux'') occurs where two or more watercourses join to form a single channel (geography), channel. A confluence can occur in several configurations: at the point where a tributary joins a larger river (main ...

with the Kangaroo River. The dam wall of is high and in length. At 100% capacity, the dam wall holds back approximately and creates the impounded reservoir of Lake Yarrunga that has a surface area of , drawn from a catchment area of . The spillway has a discharge capacity of . 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 . is available to be transferred to the Sydney water supply. Other water from Tallowa Dam is provided to

Shoalhaven City Council The City of Shoalhaven is a Local government in Australia, local government area in the South Coast, New South Wales, South Coast region of New South Wales, Australia. The area is about south of Sydney. The Princes Highway passes through the a ...

for supply to local communities. Water is also released from the dam as environmental flows for the Shoalhaven River. The construction of a large barrier across the river has meant that the means of travel for fish has been completely confounded. There was no longer any means for the fish to get to their spawning areas further upstream. An innovative fish lift was constructed in 2009 to allow the fish to be collected and transferred over the dam wall.

See also

References

Further reading