The Swan River is a river in the south west of Western Australia. Its Aboriginal Noongar name is the Derbarl Yerrigan. The river runs through the metropolitan area of Perth, Western Australia's capital and largest city.
Noongar: Derbarl Yerrigan
Map of the area around Perth, showing the location of the Swan River
|Source confluence||Avon River with Wooroloo Brook|
|- location||below Mount Mambup|
|- elevation||53 m (174 ft)|
|0 m (0 ft)|
|Length||72 km (45 mi)|
|Basin size||121,000 km2 (47,000 sq mi)|
|- left||Susannah Brook, Jane Brook|
|- right||Ellen Brook, Helena River, Bennett Brook, Canning River|
The Swan River estuary flows through the city of Perth. Its lower reaches are relatively wide and deep, with few constrictions, while the upper reaches are usually quite narrow and shallow.
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). It has three major tributaries, the Avon River, Canning River and Helena River. The latter two have dams (Canning Dam and Mundaring Weir) which provide a sizeable part of the potable water requirements for Perth and the regions surrounding. The Avon River contributes the majority of the freshwater flow. The climate of the catchment is Mediterranean, with mild wet winters, hot dry summers, and the associated highly seasonal rainfall and flow regime.
The Avon rises near Yealering, 221 kilometres (137 mi) southeast of Perth: it meanders north-northwest to Toodyay about 90 kilometres (56 mi) northeast of Perth, then turns southwest in Walyunga National Park – at the confluence of the Wooroloo Brook, it becomes the Swan River.
The Canning River rises not far from North Bannister, 100 kilometres (62 mi) southeast of Perth and joins the Swan at Applecross, opening into Melville Water. The river then narrows into Blackwall Reach, a narrow and deep stretch leading the river through Fremantle Harbour to the sea.
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. It is thought that the Wagyl/Waugal created the Swan River.
The estuary is subject to a microtidal regime, with a maximum tidal amplitude of about 1 metre (3 ft 3 in), although water levels are also subject to barometric pressure fluctuations.
Before the Tertiary, when the sea level was much lower than at present, the Swan River curved around to the north of Rottnest Island, and disgorged itself into the Indian Ocean slightly to the north and west of Rottnest. In doing so, it carved a gorge about the size of the Grand Canyon. Now known as Perth Canyon, this feature still exists as a submarine canyon near the edge of the continental shelf.
The Swan River drains the Swan Coastal Plain, a total catchment area of over 100,000 square kilometres (39,000 sq mi) in area. The river is located in a Mediterranean climate, with hot dry summers and cool wet winters, although this balance appears to be changing due to climate change. The Swan is located on the edge of the Darling Scarp, flowing downhill across the coastal plain to its mouth at Fremantle.
The Swan begins as the Avon River, rising near Yealering in the Darling Range, approximately 175 kilometres (109 mi) from its mouth at Fremantle. The Avon flows north, passing through the towns of Brookton, Beverley, York, Northam and Toodyay. It is joined by tributaries including the Dale River, the Mortlock River and the Brockman River. The Avon becomes the Swan as Wooroloo Brook enters the river near Walyunga National Park.
More tributaries including Ellen Brook, Jane Brook, Henley Brook, Wandoo Creek, Bennett Brook, Blackadder Creek, Limestone Creek, Susannah Brook, and the Helena River enter the river between Wooroloo Brook and Guildford; however, most of these have either dried up or become seasonally flowing due to human impacts such as land clearing and development.
Between Perth and Guildford the river goes through several loops. Originally, areas including the Maylands Peninsula, Ascot and Burswood, through Claise Brook and north of the city to Herdsman Lake were swampy wetlands. Most of the wetlands have since been reclaimed for land development. Heirisson Island, upon which The Causeway passes over, was once a collection of small islets known as the Hierrison Islands.
Perth Water, between the city and South Perth, is separated from the main estuary by the Narrows, over which the Narrows Bridge was built in 1959. The river then opens up into the large expanse of the river known as Melville Water. The Canning River enters the river at Canning Bridge in Applecross from its source 50 kilometres (31 mi) south-east of Armadale. The river is at its widest here, measuring more than 4 kilometres (2.5 mi) from north to south. Point Walter has a protruding spit that extends up to 800 metres (2,600 ft) into the river, forcing river traffic to detour around it.
The river narrows between Chidley Point and Blackwall Reach, curving around Point Roe and Preston Point before narrowing into the harbour. Stirling Bridge and the Fremantle Traffic Bridge cross the river north of the rivermouth. The Swan River empties into the Indian Ocean at Fremantle Harbour.
Plant and animal life found in or near the Swan-Canning Estuary include:
The river was named Swarte Swaene-Revier by Dutch explorer, Willem de Vlamingh in 1697, after the famous black swans of the area. Vlamingh sailed with a small party up the river to around Heirisson Island.
A French expedition under Nicholas Baudin also sailed up the river in 1801.
Governor Stirling's intention was that the name "Swan River" refer only to the watercourse upstream of the Heirisson Islands. All of the rest, including Perth Water, he considered estuarine and which he referred to as "Melville Water". 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."
Almost immediately after the Town of Perth was established, a systematic effort was underway to reshape the 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. An exceptionally wet winter in 1862 saw major flooding throughout the area – the effect of which was exacerbated by the extent of the reclaimed lands. The first bucket dredge in Western Australia was the Black Swan, used between 1872 and 1911 for dredging channels in the river, as well as reclamation.
A number of features of the river, particularly around the city, have reshaped its profile since European settlement in 1829:
The river has been used for the disposal all kinds of waste. Even well into the 1970s various local councils had rubbish tips on the mud flats along the edge of the river. 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. Remedial sites works are still ongoing in these areas to remove the toxins left to leach into the river.
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. The occasional accidental spillage of sewage and chemicals has also caused sections of the river to be closed to human access. The river has survived all this and is in relatively good condition considering on-going threats to its ecology.
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.
The Perth Water location on the river adjacent to the City of Perth is a popular place for viewing the annual Australia Day fireworks, with over 400,000 people crowding the foreshore, Kings Park and boats on the river.
Data collection of flood events in the estuary have been recorded since European arrival in 1829. In July 1830, barely a year after the establishment of the colony, the river rose 6 metres above its normal level.:102 New settlers were still arriving in steady numbers and few permanent buildings had been constructed, with most living in tents and other temporary accommodation. These included caves along the river's edge and many found their belongings washed away and livestock drowned. Other abnormal floods events occurred in the winters of 1847 and 1860, while the most recent flooding occurred in 2017. Later events have since been assessed for probability of recurrence:
* ARI (Average recurrence interval) is the average interval in years which would be expected to occur between exceedances of flood events of a given magnitude.
The largest recorded flood event was in July 1872 which had a calculated ARI of 100. This approximately equates to a 100-year flood event. At the Helena River, the 1872 flood level was two feet 3 inches higher that the 1862 event (ARI=60). An account in The Perth Gazette and Western Australian Journal on 26 July 1872 reported
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. The Fremantle bridge partially collapsed on 22 July 1926, five minutes after a train containing schoolchildren had passed over. No one was injured in the collapse, however it created major disruption to commerce for several months. Repairs were completed and the bridge reopened on 12 October 1926.
The Swan River Trust is a state government body, within the ambit of the Department of Environment and Conservation (Western Australia) – that was constituted in 1989 after legislation passed the previous year, that reports to the Minister for the Environment. It brings together eight representatives from the community, State and local government authorities with an interest in the Swan and Canning rivers to form a single body responsible for planning, protecting and managing Perth's river system.
The Trust meets twice a month to provide advice to the Minister for the Environment, the Western Australian Planning Commission and river border related local government bodies to guide development of the Swan and Canning rivers.
In the earliest days of the Swan River Settlement, the river was used as the main transport route between Perth and Fremantle. This continued until the establishment of the Government rail system between Fremantle and Guildford via Perth.
There are currently fifteen yacht clubs along the Swan River, with most on Melville Water, Freshwater Bay and Matilda Bay. 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. RPYC and the Royal Freshwater Bay Yacht Club are the only two clubs to be granted a royal charter. There are also many anchorages and marinas along the lower reaches near Fremantle.
There have been some north of the river or south of the river distinctions in the Perth metropolitan region over time, especially in the time up to the completion of the Causeway and Narrows bridges, due to the time and distances to cross the river.
The river is a significant part of Perth culture, with many water sports such as rowing, sailing, and swimming all occurring in its waters.
Re the 1926 flood: floodwaters spread over 5 kilometres at Guildford, and covered large areas of Perth Esplanade, and South Perth... and 12,729 million litres cascaded over Mundaring Weir