The Shoalhaven rises on the eastern side of the Great Dividing Range about 350 kilometres southwest of Sydney. The upper reaches flow northwards through an upland pastoral district near the town of Braidwood. The river works its way down into a remote canyon east of Goulburn and emerges into the coastal lowlands at Nowra in the Shoalhaven district, where it is spanned by the historic Nowra Bridge. It enters the sea at Shoalhaven Heads about 150 kilometres south of Sydney.
Tallowa Dam is the only major dam on the Shoalhaven, and is a part of the Shoalhaven Scheme. It impounds the rivers lower reaches to form Lake Yarrunga and part of Sydney's water supply. Some water is pumped out of the lake and over the Southern Highlands into Lake Burragorang. However proposals for a much larger water storage at Welcome Reef on the upper Shoalhaven have been shelved.
The Shoalhaven River and its main tributary the Kangaroo River were once renowned as an Australian bass fishery. Unfortunately, Tallowa Dam has been a potent 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. Recent stockings of hatchery bred Bass in Lake Yarrunga are a less than ideal attempt to remediate the situation. A fishway for Tallowa Dam has been discussed for more than 20 years but is yet to eventuate. Tallowa Dam has also suffered the illegal introduction of highly damaging exotic carp, which are now present in high densities.
A fish ladder is being currently built on the northern side of the dam to allow the movement of bass over the dam (2008).
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.