What is the Hawkesbury River?

The Hawkesbury River is a major river in New South Wales, flowing about 120 kilometres north of Sydney from the southern highlands through the outskirts of north-western Sydney to the Tasman Sea at Broken Bay. Its headwaters in the Wollondilly and Coxs rivers extend its catchment to about 21,400 square kilometres, the second-largest of any river in New South Wales.

The Hawkesbury and its tributary the Nepean form a continuous river known as the Hawkesbury-Nepean River system. The system flows in a great loop around Sydney, with the Nepean rising near Goulburn, flowing north through Penrith and Richmond, then becoming the Hawkesbury and curving east to the ocean. It is the main natural water source for Sydney, with Warragamba Dam on the Wollondilly arm holding the largest urban water supply in the southern hemisphere.

The river was named in 1789 by Governor Arthur Phillip after Lord Hawkesbury, then president of the Board of Trade in London. Aboriginal peoples including the Darug, Darkinjung, Eora, and Kuringgai are the Traditional Owners of the catchment. The lower Hawkesbury became one of the first agricultural districts of the colony of New South Wales, with farms established at Pitt Town, Richmond, and Windsor in the 1790s, providing Sydney with its first reliable food supplies.

The Hawkesbury periodically experiences major floods, with the lower river valley a known floodplain. Major floods in March 2021, March 2022, and July 2022 set new records for water levels at the historic Windsor flood gauge and prompted renewed debate over the proposal to raise Warragamba Dam to increase flood mitigation. The river is a popular setting for boating, fishing, and tourism, including the Riverboat Postman mail run, one of Australia's longest-running tourist services.