What we recognise today as the Derwent estuary was formed between 6,500 and 13,000 years ago when the sea level rose flooding a river valley.

Today, wetlands and shallow mud flats dominate the upper Derwent estuary, north of the Bowen Bridge. The middle estuary has a convoluted shoreline with numerous small bays and inlets. Below the Tasman Bridge there is a single large bay – Ralphs Bay – to the east and on the west a relatively straight shoreline lined with cliffs and beaches.

There are 19 conservation reserves aroundthe Derwent estuary, including:

  • Derwent River Conservation Area – the largest reserve on the estuary including most of the wetlands and mudflats north of Dogshear Point.
  • East Risdon State Reserve – one of the most intact pieces of remnant foreshore bush, this reserve includes the endangered tree species Eucalyptus risdonii and E. morrisbyi. These species are both found only on Hobart’s eastern shore.
  • Goulds Lagoon Wildlife Sanctuary – a remnant wetland listed on the Directory of Important Wetlands and open to the public for bird watching.
  • Tinderbox Marine Reserve – this underwater reserve protects a great variety of seaweeds, fish and invertebrate animals, and includes Tasmania’s only underwater snorkel trail.
  • The Ralphs Bay and South Arm reserves protect important salt marsh and wading bird habitat.
  • Mount Wellington and Hobart Town from Kangaroo Point by John Glover (detail). Image: Google Art Project.
    History of the Derwent

    Prior to the exploration and naming by the British and French, Aboriginal Tasmanians lived around the Derwent estuary for at least 6000 years.

  • Lower estuary panorama. Image: Derwent Estuary Program.
    State of the Derwent

    We publish a comprehensive State of the Derwent Report every five years as well as more frequent Report Cards, summarising the previous year’s data.

  • Chart of Van Diemen’s Land from the best authorities and from actual surveys and measurements – by Thomas Scott Assistant Surveyor General; engraved by Charles Thompson (Cross) Edinburgh. Image: Tasmanian Archive and Heritage Office.
    Publications and maps

    The Derwent Estuary Program publishes a range of material including newsletters, reports, fact sheets, and planning documents.

  • Spotted handfish. Image: Rick Stuart-Smith.
    Species of the Derwent

    A variety of unique communities of plants and animals live in the Derwent estuary, specially adapted for life between land and sea.

  • Gnarly tecticornia trunk. Image: Derwent Estuary Program.
    Habitats of the Derwent

    Many species depend on the wetlands, seagrasses, tidal flats and rocky reefs of the Derwent estuary.

  • Bioluminescence in the River Derwent at Montagu Bay, April 2021. Image: Jenny Kathy, Bioluminescence Tasmania.
    Natural phenomena

    Is that pollution in the Derwent estuary? Sometimes natural occurrences can be confused with pollution events. Here are some examples of the natural occurrences we see in the estuary. How many have you seen?

  • Crab, Hinsby Beach. Image: Parks and Wildlife Service.
    Educational resources

    The DEP has developed a range of activities focused on key estuary habitats, with support from the Australian Government’s Caring for Our Country.