River Derwent (Tasmania)

The River Derwent, also known as timtumili minanya in palawa kani,<ref>Template:Cite web</ref> is a significant river and tidal estuary in Tasmania, Australia. It begins its journey as a freshwater river in the Central Highlands at Lake St Clair, descending over Template:Convert across a distance of more than Template:Convert. At the settlement of New Norfolk in the Derwent Valley its waters become brackish, flowing through Hobart, the capital city of Tasmania, its seawater estuary eventually empties into Storm Bay and the Tasman Sea.

Historically, the banks of the Derwent were covered by forests and frequented by Aboriginal Tasmanians. With the arrival of European settlers, the area saw agricultural development and the construction of dams for hydro-electricity generation during the 20th century.

Today, the Derwent's catchment area is characterised by agriculture, forestry, and hydropower generation. It serves as a vital source of water for irrigation and urban supply, notably providing a significant portion of Hobart's water needs.<ref>Template:Cite web</ref> The river is also crucial for recreation, supporting activities such as boating, fishing, and leisure along its banks. Additionally, it facilitates marine transportation and various industrial activities, playing a central role in Tasmania's economy and lifestyle.<ref name=doe/>

Etymology

The upper part of the river was named after the River Derwent, Cumbria by British Commodore John Hayes who explored it in 1793. The name is Brythonic Celtic for "valley thick with oaks".<ref>Names of Rivers Template:Webarchive web.ukonline.co.uk</ref><ref>Celtic Place Names Template:Webarchive www.yorksj.ac.uk</ref>

Matthew Flinders placed the name "Derwent River" on all of the river.<ref>Observations on the coasts of Van Diemen's Land, on Bass's Strait and its islands, and on parts of the coasts of New South Wales; intended to accompany the charts of the late discoveries in those countries. By Matthew Flinders, second lieutenant of His Majesty's Ship Reliance.published by John Nichols 1801* page 5</ref>

The name "River Derwent" was officially endorsed on 20 May 1959.<ref>Nomenclature Board of Tasmania Nomenclature number 470L</ref>

History

The River Derwent valley was inhabited by the Mouheneener people for at least 8,000 years before British settlement.<ref>Parliament of Tasmania – House of Assembly Standing Orders Template:Webarchive "We acknowledge the traditional people of the land upon which we meet today, the Mouheneener people."</ref> Evidence of their occupation is found in many middens along the banks of the river.Template:Citation needed The first European to chart the river was Bruni d'Entrecasteaux, who named it the Rivière du Nord in 1793.<ref>Template:Cite web</ref> Later that same year, John Hayes explored the river and named it after the River Derwent, which runs past his birthplace of Bridekirk, Cumberland.<ref name=adb>Template:Australian Dictionary of Biography</ref>

When first explored by Europeans, the lower parts of the valley were clad in thick she-oak forests, remnants of which remain in various parts of the lower foreshore.<ref name="DEP"/>

There was a thriving whaling industry until the 1840s when the industry rapidly declined due to over-exploitation.<ref>Template:Cite web</ref>

File:Flock of Little Pied Cormorants.jpg

Little pied cormorants on the River Derwent

Geography

Formed by the confluence of the Narcissus and Cuvier rivers within Lake St Clair, the Derwent flows generally southeast over a distance of Template:Convert to New Norfolk and the estuary portion extends a further Template:Convert out to the Tasman Sea. Flows average in range from Template:Convert and the mean annual flow is Template:Convert.<ref name="DEP"/>

The large estuary forms the Port of the City of Hobart – the deepest sheltered harbour in the Southern Hemisphere.<ref>Tasmania River Derwent Length and Geography </ref> Some past guests of the port include Template:HMS in February 1836, carrying Charles Darwin; the Template:USS; Template:USS and Template:USS. The largest vessel to ever travel the Derwent is the Template:Convert, Template:Convert high, ocean liner Diamond Princess, which made her first visit in January 2006.<ref>Template:Cite web</ref>

At points in its lower reaches the river is nearly Template:Convert wide, and as such is the widest river in Tasmania.Template:Citation needed

The Derwent estuary contains dozens of white sandy beaches, many of which are staples of local activity within Hobart suburbs and include Bellerive Beach, Blackmans Bay Beach, Howrah Beach, Nutgrove Beach, Lords Beach, Long Beach, Taroona Beach, Hinsby Beach, Kingston Beach and Windermere Beach.

Hydro schemes

Until the construction of several hydro-electric dams between 1934 and 1968, the river was prone to flooding.Template:Citation needed Now there are more than twenty dams and reservoirs used for the generation of hydro-electricity on the Derwent and its tributaries, including the Clyde, Dee, Jordan, Nive, Ouse, Plenty and Styx rivers. Seven lakes have been formed by damming the Derwent and the Nive rivers for hydroelectric purposes and include the Meadowbank, Cluny, Repulse, Catagunya, Wayatinah, Liapootah and King William lakes or lagoons.

River health

The Upper Derwent is affected by agricultural run-off, particularly from land clearing and forestry. The Lower Derwent suffers from high levels of toxic heavy metal contamination in sediments. The Tasmanian Government-backed Derwent Estuary Program has commented that the levels of mercury, lead, zinc and cadmium in the river exceed national guidelines. In 2015 the program recommended against consuming shellfish and cautioned against consuming fish in general. Nutrient levels in the Derwent between 2010 and 2015 increased in the upper estuary (between Bridgewater and New Norfolk) where there had been algal blooms.<ref name="DEP">Template:Cite news</ref>

Industrial pollution

Template:See also A large proportion of toxic heavy metal contamination stems from legacy pollution caused by major industries that discharge into the river including Nyrstar Hobart, a historic smelter establish at Lutana in 1916,<ref>Template:Cite web</ref> and the Norske Skog Boyer paper mill at Boyer which opened in 1941.<ref>Template:Citation</ref><ref>Template:Citation</ref><ref>Template:Citation</ref><ref>Template:Citation</ref>

The Derwent adjoins or flows through the Pittwater–Orielton Lagoon, Interlaken Lakeside Reserve and Goulds Lagoon, all wetlands of significance protected under the Ramsar Convention.<ref name=doe/>

Flora and fauna

File:Brachionichthys hirsutus RLS.jpg

The critically endangered spotted handfish

In recent years, southern right whales finally started making appearance in the river during months in winter and spring when their migration takes place. Some females even started using calm waters of the river as a safe ground for giving birth to their calves and would stay over following weeks after disappearance of almost 200 years due to being wiped out by intense whaling activities. In the winter months of 2014, humpback whales and a minke whale (being the first confirmed record of this species in the river) have been recorded feeding in the River Derwent for the first time since the whaling days of the 1800s.<ref>Template:Cite web</ref>

The rare spotted handfish (Brachionichthys hirsutus), whose only habitat is in the Derwent estuary and surrounds,<ref name=fishbase/> was the first marine fish to be listed as critically endangered in the IUCN Red List, in 1996.<ref>Template:Cite journal</ref><ref>Edgar, G., Stuart-Smith, R. & Last, P.R. (2020). Brachionichthys hirsutus. The IUCN Red List of Threatened Species. Template:Doi</ref> The fish is threatened by the Northern Pacific seastar's invasion into southern Australian waters. The Northern Pacific seastar (Asterias amurensis), now firmly established in the Derwent,<ref name=gisd/><ref name=nimpis>Template:Cite web</ref> preys on not only the fish eggs,<ref name=fishbase>Template:Cite web</ref> but also on the sea squirts (ascidians)<ref name=gisd>Template:Cite web</ref> that help to form the substrate that the fish spawn on.<ref name=abc2021>Template:Cite web</ref>

Bridges

Several bridges connect the western shore (the more heavily populated side of the river) to the eastern shore of Hobart – in the greater Hobart area, these include the five lane Tasman Bridge, near the CBD, just north of the port; the four lane Bowen Bridge; and the two lane Bridgewater Bridge and Causeway. Until 1964 the Derwent was crossed by the unique Hobart Bridge, a floating concrete structure just upstream from where the Tasman Bridge now stands.<ref>Template:Cite web</ref>

Travelling further north from the Bridgewater crossing, the next crossing point is the Blair Street Bridge at New Norfolk, slightly north of the point where the Derwent reverts from seawater to fresh water, Bushy Park, Upper Meadowbank Lake, Lake Repulse Road, Wayatinah, and the most northerly crossing is at Derwent Bridge, before the river reaches its source of Lake St Clair. At the Derwent Bridge crossing, the flow of the river is generally narrow enough to be stepped across.

Cultural references

The river is the subject of the multimedia performance "Falling Mountain" (2005 Mountain Festival), a reference to the mountain in the Cradle Mountain-Lake St Clair National Park from which the river rises.

The Derwent is mentioned in the song, Mt Wellington Reverie by Australian band, Augie March.<ref>Template:Cite web augie-march.com Retrieved 6 January 2013</ref> Hobart is located in the foothills of Mount Wellington.

See also

• Bridgewater Jerry
• Ferries in Hobart
• Hydro Tasmania
• List of rivers of Tasmania
• Plenty, Tasmania
• Whaling in Australia
• List of deepest natural harbours

External links

• Derwent Estuary Program
• Upper Derwent Issues
• Template:Cite map
• Template:Cite web