Pittwater is a semi-mature tide dominated drowned valley estuary, located about north of the Sydney central business district, New South Wales, Australia; being one of the bodies of water that separate greater Metropolitan Sydney from the Central Coast. Pittwater has its origin from the confluence of McCarrs Creek, to the west of Church Point and a number of smaller estuaries, the largest of which is Cahill Creek, that joins the Pittwater north of Mona Vale. The Pittwater is an open body of water, often considered a bay or harbour, that flows north towards its mouth into Broken Bay, between West Head and Barrenjoey Head, less than from the Tasman Sea. The total area of the Pittwater is and around ninety percent of the area is generally administered by the Hawkesbury–Nepean Catchment Management Authority, in conjunction with Northern Beaches Council. The land adjacent to the Pittwater was occupied for many thousands of years by the Kuringgai peoples, an Aboriginal Australian grouping of uncertain origin. They used the river as an important source of food and a place for trade. Pittwater was named Pitt Water in 1788 in honour of William Pitt the Younger, the then Prime Minister of the United Kingdom. Geography Pittwater extends from Mona Vale and Warriewood in the south, along the eastern ridge of the Barrenjoey Peninsula leading to Palm Beach and along the western ridge of the Lambert Peninsula leading to West Head. The eastern parts of the catchment are largely urbanised whilst the western parts are primarily Ku-ring-gai Chase National Park. Within the Pittwater lies Careel Bay, Refuge Cove, Saltpan Cove, Horseshoe Cove, Crystal Bay, McCarrs Creek, Browns Bay, Elvina Bay, Lovett Bay, Towlers Bay, Portuguese Bay, Coasters Retreat and The Basin. Scotland Island is located within the estuary. Pittwater contains a diversity of estuarine habitat types including mangrove wetlands, saltmarsh, sand flats and seagrass meadows, including threatened areas of coastal saltmarsh. History Aboriginal history The Dharug peoples were the traditional inhabitants of the land and waterways north and south of Sydney Harbour, from Botany Bay in the south, inland along the Parramatta River and through the Lane Cove River and across Broken Bay and beyond to Brisbane Water. Amongst the Dharug there were many smaller units called clans, of which the Garigal were most prominent in the area surrounding Pittwater and the Northern Beaches. During 1789 the impact of smallpox on aboriginal peoples led to