The Swan River drains the Avon and coastal plain catchments, which have a total area of about 121,000 square kilometres (47,000 sq mi).

The climate of the catchment is Mediterranean, with mild wet winters, hot dry summers, and the associated highly seasonal rainfall and flow regime.

The Canning River rises from North Bannister, 100 kilometres (62 mi) southeast of Perth and joins the Swan at Applecross, opening into Melville Water.

The Swan begins as the Avon River, rising near Yealering in the Darling Range, approximately 175 kilometres (109 mi) from its mouth at Fremantle.

Originally, areas including the Maylands Peninsula, Ascot and Burswood, through Claise Brook and north of the city to Herdsman Lake were swampy wetlands.

Plant and animal life found in or near the Swan-Canning Estuary include: The river was named Swarte Swaene-Revier[10] by Dutch explorer, Willem de Vlamingh in 1697, after the famous black swans of the area.

[12]: 138–145 Governor Stirling's intention was that the name "Swan River" refer only to the watercourse upstream of the Heirisson Islands.

The Government notice dated 27 July 1829 stated "... the first stone will be laid of a new town to be called 'Perth', near the entrance to the estuary of the Swan River."

This was done for many reasons: Perth streets were often sandy bogs which caused Governor James Stirling in 1837 to report to the Secretary of State for Colonies: At the present time it can scarcely be said that any roads exist, although certain lines of communication have been improved by clearing them of timber and by bridging streams and by establishing ferries in the broader parts of the Swan River ...Parts of the river required dredging with the material dumped onto the mud flats to raise the adjoining land.

Heavy industry also contributed its share of waste into the river from wool scouring plants in Fremantle to fertiliser and foundries sited in the Bayswater – Bassendean area.

During the summer months there are problems with algal blooms killing fish and caused by nutrient run-off from farming activities as well as the use of fertilisers in the catchment areas.

In 2010 the Western Australian government imposed restrictions on phosphorus levels in fertilisers due to concerns about the health of the Swan and Canning river system.

An account in The Perth Gazette and Western Australian Journal on 26 July 1872 reported[16] In and about Perth, the water owing to the force of the incoming seas at the mouth of the river presented a scene of a great lake, all the jetties were submerged, the high roads to Fremantle covered, and passage traffic rendered impossible quantities of sandalwood lying along the banks of river were washed away, and the inhabitants of the suburban villas on the slopes of Mount Eliza obliged to scramble up the hill sides to get into Perth.The flood of July 1926 (ARI=30) resulted in the washing away of the Upper Swan Bridge and a section of the Fremantle Railway Bridge.

[20][21] The functions of the Trust have been absorbed by the subsequent Western Australian Environmental protection authorities, the most recent change being in 2017, to the Department of Biodiversity, Conservation and Attractions.

Royal Perth Yacht Club, on Pelican Point in Matilda Bay, staged the unsuccessful 1987 America's Cup defence, the first time in 132 years it had been held outside of the United States.

The Noongar people believe that the Darling Scarp represents the body of a Wagyl (also spelt Waugal) – a snakelike being from Dreamtime that meandered over the land creating rivers, waterways and lakes.