The headwaters of the Hawkesbury, the Avon River, the Cataract River, and the Cordeaux River, rise only a few miles from the sea, about 80 kilometers south of Sydney. These streams start on the inland-facing slopes of the plateau which forms the escarpment behind Wollongong. Flowing north-west, away from the sea, these streams combine to form the Nepean River. Flowing north past the towns of Camden and Penrith, the Nepean forms the western boundary of the Sydney region.
Near Penrith, the Warragamba River emerges from its canyon through the Blue Mountains and joins the Nepean. The Warragamba, formed by the joining of the Wollondilly River, the Nattai River, the Kowmung River and Cox's River drains a broad region of New South Wales on the eastern side of the Great Dividing Range.
North of Penrith, the Nepean is joined by the Grose River and its name changes to Hawkesbury. It passes the towns of North Richmond and Windsor, and winds eastwards through majestic scenery to reach the ocean at Broken Bay. The Colo River and the Macdonald River are major tributaries of the Hawkesbury. The upper reaches of various tributaries of the Hawkesbury are the main water supply areas for Sydney, forming the Nepean, Cordeaux, Avon and Cataract Dams.
There are various crossings of the river along its length starting with the Hawkesbury River Railway Bridge at Brooklyn, Peats Ferry Bridge and The Sydney-Newcastle Freeway Bridge between Kangaroo Point and Mooney Mooney, the vehicular ferry at Wisemans Ferry the Putty Road Bridge at Windsor, the bridge just north of Richmond which carries Bells Line of Road, the rail bridge at Penrith and Victoria Bridge at Penrith for road traffic.
The Aboriginal name for the river was recorded as Deerubbun. The two main aboringal tribes inhabiting the area were the Dhurag or Darug people to the north and west and the Kuringgai people to the east.
In 1788 two expeditions explored the Hawkesbury to the northwest of Sydney and the Nepean River to the southwest. It took about three years to realise they had discovered the same river and given it two different names. It is therefore often referred to as the Hawkesbury-Nepean River with the name change occurring north of Penrith.
The Hawkesbury River was used as one of the major transportation routes for transporting food from western Sydney, to the city during the 1800s. Boats and Barges would then wait in the protection of Broken Bay and Pittwater, until favourable weather before making the 14km ocean journey to Sydney.
The Hawkesbury River was named by Governor Phillip in June 1789, after Charles Jenkinson, 1st Earl of Liverpool, who at that time was titled Baron Hawkesbury. An obelisk was unveiled in 1939 at Brooklyn to commemorate the naming.
In 1794, 22 families were granted land at Bardenarang, now known as Pitt Town Bottoms, near Windsor.. In that same year, confrontations between Aboriginal people and settlers broke out.
According to the Hawkesbury Nepean Catchment Management Authority, the Hawkesbury River estuary supports the second largest commercial coastal fishery of estuary prawns, oysters (prior to the outbreak of QX disease ) and fish in NSW with a wholesale value of $6.3 million annually.