|Location||Greater Metropolitan Sydney, New South Wales|
|Type||Semi-mature tide dominated, drowned valley estuary|
|Part of||Sydney Harbour|
|Primary inflows||Middle Harbour Creek|
|Primary outflows||Port Jackson|
|Catchment area||100 km2 (39 sq mi)|
|Max. length||10 km (6.2 mi)|
Middle Harbour (or Warring-Ga), a semi–mature tide dominated drowned valley estuary, is the northern arm of Port Jackson, an inlet of the Tasman Sea located north of Sydney central business district on the coast of New South Wales, Australia.
Middle Harbour has its source in the upper reaches of Garigal National Park where it forms Middle Harbour Creek and flows southeast to become Middle Harbour at Bungaroo and travels for approximately 10 kilometres (6.2 mi) before reaching its mouth at Port Jackson between Grotto Point near Clontarf and Middle Head.
The catchment area of Middle Harbour is approximately 100 square kilometres (39 sq mi).
This section needs additional citations for verification. (August 2008)
The shore of Middle Harbour is nearly everywhere rugged, barren and forested and for this reason Middle Harbour was almost entirely neglected during the first two centuries of European settlement in Sydney. There are only a few small patches of flat land on its shores. There are many small creeks draining the surrounding hills, but no significant rivers flow into Middle Harbour.
Within Middle Harbour are, from upstream to downstream, Shell Cove, Pearl Bay, Long Bay, Sugarloaf Bay, Bantry Bay, Fisher Bay, Sandy Bay, Sailors Bay, Powder Hulk Bay, Willoughby Bay and Quakers Hat Bay.
Since the 1920s, most of the land on the ridge-tops around Middle Harbour has been developed for suburban housing. Much of the rugged shore of the Middle Harbour remains covered with bushland, most of it now protected by parks and reserves. Middle Harbour is a popular area for recreational boating and fishing.
- Roy, P. S; Williams, R. J; Jones, A. R; Yassini, I; et al. (2001). "Structure and Function of South-east Australian Estuaries". Estuarine, Coastal and Shelf Science. 53 (3): 351–384. doi:10.1006/ecss.2001.0796.
- "Middle Harbour". Geographical Names Register (GNR) of NSW. Geographical Names Board of New South Wales. Retrieved 5 January 2013.
- "Sydney Harbour and Parramatta River catchment" (map). Office of Environment and Heritage. Government of New South Wales.
- NSW State of the Beaches 2011–2012: Sydney Estuarine Beaches region p. 242
- Sydney Metropolitan Catchment Management Authority