Derwent Estuary and its catchment

Derwent Estuary - map 

Derwent Estuary—map (PDF - 702 KB)

About the catchment

The Derwent Estuary catchment covers 8 500 km2, which is the entirety of the Derwent River drainage basin.
The source is Lake St Clair in the north-west near Derwent Bridge and the main sub-systems in the catchment are the Derwent, Ouse, Clyde and Jordan rivers.

The Derwent Estuary itself extends from New Norfolk to the Iron Pot lighthouse off South Arm and covers approx 200 km2 adjacent to the Hobart metropolitan area.

Values to be protected

The Derwent Estuary is an important and productive ecosystem and supports a wide range of habitats and species. Nearly 40% of Tasmania's population lives around the estuary's margins and the Derwent is widely used for recreation, boating, recreational fishing, marine transportation and industry. Further upstream, the Derwent River supplies the majority of the region's drinking water supply and is a major source of hydroelectric power.

Ramsar sites

  • Pitt Water-Orielton Lagoon
  • Interlaken (Lake Crescent)
  • River Derwent, Goulds Lagoon are identified in the Directory of Wetlands of National Importance

Water quality issues

A number of environmental issues affect the Derwent Estuary, in particular:

  • heavy metal contamination of sediments and biota
  • elevated nutrients, organic-rich sediments and locally depressed oxygen levels
  • occasional faecal contamination of recreational waters
  • altered environmental flows and physical barriers to fish migration
  • introduced marine pests and weeds
  • loss and degradation of estuarine habitat and species.

Key water quality improvement projects

  • Derwent Estuary Water Quality Improvement Plan for Heavy Metals

Key stakeholders/agencies

  • Derwent Estuary Program—a partnership between the Tasmanian State Government, the six councils that border on the estuary (Brighton, Clarence, Derwent Valley, Glenorchy, Hobart and Kingborough) and four industry partners (Hobart Water, Norske Skog Boyer, Nyrstar Hobart and TasPorts).