The Shoalhaven River rises approximately 50km inland of Moruya and follows a northerly direction for 170km before turning east for a further 90km to reach the Pacific Ocean at Crookhaven Heads. Two hundred years ago the main entrance was at Shoalhaven Heads. This entrance is now intermittent following the construction of the Berry’s Canal link to the Crookhaven River in 1822. The valley can be categorised into three broad regions:

• upstream of Welcome Reef where the terrain is rolling plateau,
• between Welcome Reef and Nowra where the catchment consists of steep forested country with the main streams entrenched in deep gorges,
• downstream of Nowra where an expansive floodplain has developed.

The floodplain area was formed by the infilling of an old coastal lagoon. The southern part of the floodplain is drained by the Crookhaven River, which rises near Nowra, while the northern section is drained by Broughton Creek, which rises upstream of Berry. Flood behaviour in the area has been extensively modified since European settlement through the construction of flood mitigation and bank protection works. The excavation of Berry’s Canal has also had a major impact by opening up a second entrance at Crookhaven Heads.