Editing River Derwent (Tasmania) (section)

==Geography==
Formed by the confluence of the Narcissus and Cuvier rivers within [[Lake St Clair, Tasmania|Lake St Clair]], the Derwent flows generally southeast over a distance of {{convert|187|km}} to [[New Norfolk, Tasmania|New Norfolk]] and the estuary portion extends a further {{convert|52|km}} out to the Tasman Sea. Flows average in range from {{convert|50|to|140|m3/s}} and the mean annual flow is {{convert|90|m3/s}}.<ref name="DEP"/>

The large [[estuary]] forms the [[Port of Hobart|Port]] of the City of [[Hobart]] – the deepest sheltered [[harbour]] in the [[Southern Hemisphere]].<ref>[https://tasmania.com/points-of-interest/river-derwent Tasmania] River Derwent Length and Geography </ref> Some past guests of the port include {{HMS|Beagle||6}} in February 1836, carrying [[Charles Darwin]]; the {{USS|Enterprise|CVN-65|6}}; {{USS|John C. Stennis|CVN-74|6}} and {{USS|Missouri|BB-63|6}}. The largest vessel to ever travel the Derwent is the {{convert|113000|t|LT|adj=on}}, {{convert|61|m|adj=on}} high, ocean liner ''[[Diamond Princess (ship)|Diamond Princess]]'', which made her first visit in January 2006.<ref>{{cite web |url=http://www.tasports.com.au/port_services/hobart.html |title=Shipping Movements List for Hobart |access-date=3 October 2017 |location=Australia |work=[[TasPorts]] |url-status=live |archive-url=https://web.archive.org/web/20160327051954/http://www.tasports.com.au/port_services/hobart.html |archive-date=27 March 2016 }}</ref>

At points in its lower reaches the river is nearly {{convert|3|km}} wide, and as such is the widest river in Tasmania.{{citation needed|date=July 2015}}

The Derwent estuary contains dozens of white sandy beaches, many of which are staples of local activity within Hobart suburbs and include [[Bellerive Beach, Tasmania|Bellerive Beach]], [[Blackmans Bay, Tasmania|Blackmans Bay Beach]], [[Howrah Beach]], [[Nutgrove Beach, Tasmania|Nutgrove Beach]], [[Lords Beach, Tasmania|Lords Beach]], [[Long Beach, Tasmania|Long Beach]], [[Taroona Beach, Tasmania|Taroona Beach]], [[Hinsby Beach, Tasmania|Hinsby Beach]], [[Kingston Beach, Tasmania|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.{{citation needed|date=July 2015}} 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 River (Tasmania)|Clyde]], [[Dee River (Tasmania)|Dee]], [[Jordan River (Tasmania)|Jordan]], [[Nive River (Tasmania)|Nive]], [[Ouse River (Tasmania)|Ouse]], [[Plenty River (Tasmania)|Plenty]] and [[Styx River (Tasmania)|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 [[methylmercury|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 bloom]]s.<ref name="DEP">{{cite news |url=http://www.abc.net.au/news/2015-04-23/state-of-the-derwent-heavy-metals-down-effluent-up/6416182 |date=23 April 2015 |author=Shannon, Lucy |title=River Derwent: Heavy metal contamination decreases, effluent increases, report finds |publisher=[[ABC News (Australia)|ABC News]]|location=Australia |access-date=3 July 2015 |url-status=live |archive-url=https://web.archive.org/web/20150704234728/http://www.abc.net.au/news/2015-04-23/state-of-the-derwent-heavy-metals-down-effluent-up/6416182 |archive-date=4 July 2015 }}</ref>

====Industrial pollution====
{{See also|Risdon Zinc Works#Pollution}}
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>{{cite web|url=http://www.historycooperative.org/proceedings/asslh/barton.html|title=Communal life, common interests and healthy conditions|author=Ruth Barton|url-status=dead|archive-url=https://web.archive.org/web/20120214093823/http://www.historycooperative.org/proceedings/asslh/barton.html|archive-date=14 February 2012}}</ref> and the [[Norske Skog Boyer]] paper mill at [[Boyer, Tasmania|Boyer]] which opened in 1941.<ref>{{Citation | author1=Environmental Geochemistry Services | author2=Tasmania. Dept. of Environment and Planning | author3=Menzies Centre for Population Health Research | author4=John Miedecke and Partners | title=Investigation of heavy metals in soil and vegetation around the Pasminco Metals-EZ refinery, Hobart : stage 1 | publication-date=1991 | publisher=Dept. of Environment and Planning | url=http://trove.nla.gov.au/work/34468748 | access-date=12 June 2015 }}</ref><ref>{{Citation | author1=Environmental Geochemistry International | author2=Tasmania. Dept. of Environment and Planning | author3=John Miedecke and Partners | title=Heavy metals in soil and vegetation in the vicinity of the Pasminco Metals-EZ refinery, Hobart | publication-date=1992 | publisher=Dept. of Environment and Planning | url=http://trove.nla.gov.au/work/34469127 | access-date=12 June 2015 }}</ref><ref>{{Citation | author1=TASUNI Research. Aquahealth Division | author2=Jeffries, Maria | author3=Tasmania. Department of Primary Industry and Fisheries | author4=Australian Government Analytical Laboratories | author5=Tasmania. Department of Environment and Land Management | author6=Lutana Soil Contamination Working Group (Tas.) | title=Investigation of heavy metals in indoor dust, soils and home-grown vegetables : investigations in the vicinity of the Pasminco Metals-EZ refinery, Hobart | publication-date=1995 | publisher=Dept. of Environment and Land Management | url=http://trove.nla.gov.au/work/14888080 | access-date=12 June 2015 }}</ref><ref>{{Citation | author1=Dames & Moore | author2=Pasminco Metals – EZ | author3=Pasminco Australia Limited | title=Development proposal & environmental management plan : a proposal to implement the paragoethite co-treatment process at Pasminco Metals-EZ | publication-date=1995 | publisher=Pasminco Ltd | url=http://trove.nla.gov.au/work/21481760 | access-date=12 June 2015 }}</ref>

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