The ''Black Swan'' was the first bucket dredge used by the

Swan River Colony The Swan River Colony, also known as the Swan River Settlement, or just Swan River, was a British colony established in 1829 on the Swan River, in Western Australia. This initial settlement place on the Swan River was soon named Perth, and it ...

(now

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

) to make its rivers more suitable for shipping. The dredge was operational from 1872 to 1911, when it was scuttled. Initially known as the Government Dredge, it was renamed after being repaired and modified between 1887 and 1888. The dredging carried out by the ''Black Swan'' and other vessels had a significant impact on the river fauna and flora, including the

black swan The black swan (''Cygnus atratus'') is a large waterbird, a species of swan which breeds mainly in the southeast and southwest regions of Australia. Within Australia, the black swan is nomadic, with erratic migration patterns dependent upon c ...

s for which it was named.

Design and construction

The need for dredging the

Canning Canning is a method of food preservation in which food is processed and sealed in an airtight container (jars like Mason jars, and steel and tin cans). Canning provides a shelf life that typically ranges from one to five years, although u ...

and Swan Rivers, particularly around

Perth Water Perth Water is a section of the Swan River on the southern edge of the central business district of Perth, Western Australia. It is between the Causeway to the east, and Narrows Bridge to the west – a large wide but shallow section of river, ...

, had been identified as early as 1865. The shallow waters limited opportunities for trade, forcing cargo to be loaded and unloaded at the end of the Swan River, near

Fremantle Fremantle () () is a port city in Western Australia, located at the mouth of the Swan River in the metropolitan area of Perth, the state capital. Fremantle Harbour serves as the port of Perth. The Western Australian vernacular diminutive for ...

. In 1869 the government ordered a dredge from England, which arrived in segments at Fremantle in 1869 and was assembled in . The dredge was long, with a beam of , and a 12-horsepower steam engine, that could be operated at up to 32 horsepower when assisted by a

flywheel A flywheel is a mechanical device which uses the conservation of angular momentum to store rotational energy; a form of kinetic energy proportional to the product of its moment of inertia and the square of its rotational speed. In particular, ass ...

. There were 18 buckets attached to the bucket ladder, which was located in the centre of the vessel, and enabled dredging to a depth of approximately . By 1887, having been left unused for several years, the steel bottom of the vessel had rusted through in various locations. Repairs were made between 1887 and 1888. The bottom was replaced with

jarrah ''Eucalyptus marginata'', commonly known as jarrah, djarraly in Noongar language and historically as Swan River mahogany, is a plant in the myrtle family, Myrtaceae and is endemic to the south-west of Western Australia. It is a tree with roug ...

, and at the same time the bucket ladder was modified. It was relocated to the bow, lengthened, and four extra buckets were added, which allowed the dredging depth to be increased to .

Operational history

Work began in 1872, using convict labour, on the dredging of a path between The Narrows and the William Street jetty, to allow the passage of cargo. This was extended up to Barrack Street, which was the site of King Cole's jetty. The dredge was also used around Fremantle several times, to remove sand banks and to assist boats travelling to the jetty at Pier Street. Following work on the Perth foreshore

reclamation Reclaim, reclaimed, reclaimer, reclaiming or reclamation means "to get something back". It may refer to: * Land reclamation, creating new land from oceans, riverbeds, or lake beds * Dedesertification, reversing of the land degradation in arid ...

in the 1870s, which used silt from the channels dredged in

, the vessel was left sitting in the Perth foreshore for several years. Following the repairs made in 1887 and 1888, the dredge was officially launched and renamed the ''Black Swan'', on 19 June 1888. It took its name from the Swan River, which was named after the

s living in the area. The first works done following this involved modifications to the mouth of the Swan River.''Wanderer'' visits and views the dredger at Fremantle In 1892, the ''Black Swan'' was deployed to the Canning River, to cut a channel in the area known as Muddy Reach. Following this job, the dredge was taken back to the Perth Water, where it constructed a channel linking Barrack Street in Perth with Mends Street in , near the Perth Zoo. Following this, the ''Black Swan'' was used to dredge a channel between Barrack Street and Coode Street, and in 1900 widened the Barrack Street – Mends Street channel. For the next decade the dredge was used on reclamation projects in Perth.

Decommissioning and legacy

In 1911, the reclamation works in Perth were completed. Subsequently, the equipment used on the project, including the ''Black Swan'' was taken out beyond the North Mole and sunk. Modifications made to the river, including the dredging of shallow Perth Waters, impacted the biodiversity of the Perth area. River shallows are important for fish breeding grounds, and provided food and shelter for the native black swans, after which the Swan River was named.{{cite web, title=Premier unveils plan to return Black Swans to river, url=http://www.mediastatements.wa.gov.au/ArchivedStatements/Pages/CourtCoalitionGovernmentSearch.aspx?ItemId=112902&minister=Court&admin=Court, archive-url=https://web.archive.org/web/20091004041830/http://www.mediastatements.wa.gov.au/ArchivedStatements/Pages/CourtCoalitionGovernmentSearch.aspx?ItemId=112902&minister=Court&admin=Court, url-status=dead, archive-date=4 October 2009, work=Ministerial Media Statements, publisher=Government of Western Australia, accessdate=11 November 2012, date=2 December 2000 Increasing the depth of the river put much of the swans' aquatic plant food supply out of reach, resulting in loss of habitat. In 2000, the state government released a plan to combat the decrease in black swan numbers due to dredging and other river modification, through habitat rehabilitation and recreation.

References

Swan River (Western Australia) Dredgers Canning River (Western Australia)