|Name origin: In honour of Henry Hacking, a pilot at Port Jackson|
|State||New South Wales|
|Regions||Sydney basin (IBRA), Southern Sydney|
|Local government areas||Wollongong, Sutherland|
|- location||below Kellys Falls|
|- elevation||91 m (299 ft)|
|- location||west of|
|- elevation||7 m (23 ft)|
|Length||26 km (16 mi)|
|National park||Royal National Park|
|Nature reserve||Garawarra State Conservation Park|
Drawing its source from the east north-eastern runoff of the Illawarra escarpment, drained via Kellys Creek, the Hacking River rises below Kelly Falls, about 3 kilometres (1.9 mi) south of , east of the Princes Highway and west of . The river flows generally north north-east before reaching its mouth and emptying into Port Hacking at a line between between Grays Point and Point Danger, about 4 kilometres (2.5 mi) east of the suburb of , west of . The river descends 84 metres (276 ft) over its 26 kilometres (16 mi) course.
Most of the river flows through the Garawarra State Conservation Park and the Royal National Park. The river is named in honour of Henry Hacking, a pilot at Port Jackson in colonial New South Wales.
Its upper reaches lie adjacent to the red and green spots of the bright Garawarra State Conservation Area, where it is a small stream in a gully within rainforest. The river passes through a variety of plant communities, such as dry eucalyptus forest, tall wet eucalyptus forest and rainforests. Significant rainforest plants growing by the river banks include White Beech, Citronella, Supplejack, Bangalow Palm, Jackwood and Golden Sassafras. The Blackbutt, Grey Ironbark and Sydney Blue Gum are common eucalyptus trees. As it moves downstream, it flattens and widens before it reaches the estuary at Port Hacking.
A variety of molluscs, crustaceans, insects, fish and birds live in and around the river. Long Finned Eels migrate from oceanic spawning grounds as elvers. As adults they mature in the creeks and streams of the Royal National Park, sometimes to be seen in the river pools. Jollytail are common small fish. Platypus may occasionally be seen in the river, and Azure Kingfishers nest in the river banks. The land snail Meridolum marshalli is restricted to Royal National Park; its main habitat is wet areas near the river.
History and human development
For more than 8,000 years prior to 1840, the Tharawal (or Dharwal) people occupied the catchment area evidenced by hundreds of Aboriginal artefacts, middens, rock carvings and cave paintings. In the mid 19th century shell grit was in high demand as a source of lime for building in the Sydney district. Consequently, mud and oyster rocks were collected in large numbers from Port Hacking catchment destroying a number of aboriginal midden sites in the region.
A causeway, built in 1899, crosses the Hacking River at Audley within the Royal National Park. Here, mangrove flats were cleared to make way for boat-sheds and accommodation in the late 19th century. A boatshed and picnic grounds remain at Audley, having been used continuously since. Visitors can canoe and kayak further upstream along the Hacking River or its tributary Kangaroo Creek.
The soft soils are vulnerable to erosion, which is exacerbated by bushwalking. Erosion is facilitated by relatively high rainfall in the Garrawarra State Conservation Area. Furthermore, runoff from the towns of Helensburgh, Otford and Stanwell Tops (which lie above the catchment) has also impacted on water quality in the river, resulting in increased turbidity and algal growth.
Within the Royal National Park at, visitors have enjoyed picnic and boating facilities for more than a hundred years.
- "Hacking River". Geographical Names Register (GNR) of NSW. Geographical Names Board of New South Wales. Retrieved 29 December 2013.
- "Port Hacking (Bay)". Geographical Names Register (GNR) of NSW. Geographical Names Board of New South Wales. Retrieved 8 January 2013.
- "Map of Hacking River, NSW". Bonzle Digital Atlas of Australia. Retrieved 29 December 2013.
- "Hacking River". NSW Water Quality and River Flow Objectives. Government of New South Wales. 1 May 2006. Retrieved 20 August 2011.
- NSW National Parks & Wildlife Service (February 2000). "Royal National Park, Heathcote National Park and Garawarra State Recreation Area: Plan of Management" (PDF). Sydney: Government of New South Wales. Retrieved 20 August 2011.
- Floyd, A. G. (1990). Australian Rainforests in New South Wales. Volume 2. p. 116. ISBN 0-949324-32-9.
- "Otford Eco".
- "Port Hacking Integrated Environmental Management Plan" (PDF). Sutherland Shire Council. 2008. p. 31. Retrieved 8 January 2012.
- Curby, Pauline (2002). Pictorial History Sutherland Shire. Kingsclear Books Pty Ltd. p. 36. ISBN 0-908272-79-0.