Hobart area residents are fortunate in having easy access to a variety of safe, sandy beaches within 20 minutes of the CBD. This is increasingly rare for a capital city and adds greatly to our quality of life. Swimming and other water sports such as small boat sailing, rowing, windsurfing and water-skiing are also enjoyed at sites up and down the estuary.

The program tests water quality at 19 swimming sites around the Derwent estuary. Weekly results are published below, and on the DEP Facebook page. Based on five years of data, most Derwent swimming sites are classified as having Good or Fair water quality.

Blackmans Bay Beach

Blackmans Bay Beach

Snorkelling is a fun thing to do and you may be lucky enough to see a weedy seadragon from this beach.

Beach Watch 21 June 2024

Most importantly, DO NOT swim in the estuary for two days after heavy rain, or at any time near stormwater pipes and urban rivulets.

Definitions

New

Daily 9am pollution forecast (trial)
  • UNLIKELY Pollution is unlikely; enjoy your swim!
  • POSSIBLE Pollution is possible; take care.
  • LIKELY Pollution is likely; avoid swimming today.
  • N/A Result not available.
  • Additional information icon Additional information available.

Read about the pollution forecasting trial during the 2023–24 Beach Watch season.

The forecasts are predictions of water quality only and may not be 100% accurate. Derwent Estuary Program cannot guarantee the accuracy of any results or outputs from this model. Any reliance you place on this information is strictly at your own risk.

Long-term rating (based on 5 years of monitoring)
  • GOOD Water quality is usually good for swimming.
  • FAIR Water quality is usually fair for swimming, but occasionally requires retesting.
  • POOR Swimming is not advised.
  • N/A Long-term grade not available (site has not been monitored for 5 years).
Weekly sample result
  • PASS OK for swimming.
  • RETEST Retest required.
  • FAIL Swimming not recommended.
  • N/A Result not available.
  • Numerical readings represent enterococci MPN (Most Probable Number) per 100 mL.

Bay Watch 21 June 2024

Most importantly, DO NOT swim for several days after heavy rain or at any time near stormwater pipes and rivulets.

Definitions

Long-term rating (based on 5 years of monitoring)
  • GOOD Water quality is usually good for swimming.
  • FAIR Water quality is usually fair for swimming.
  • POOR Swimming is not advised.
  • N/A Long-term grade not available (site has not been monitored for 5 years).
Weekly sample result
  • PASS OK for swimming.
  • RETEST Retest required.
  • FAIL Swimming not recommended.
  • N/A Result not available.
  • Numerical readings represent enterococci MPN (Most Probable Number) per 100 mL.

Important points

Has there been heavy rain in the past two days?

Avoid swimming in the Derwent estuary for two days after heavy rain (> 10 mm rain over a 24 hour period) as beaches are likely to be polluted by stormwater. Check back regularly for the latest results.

For swimming event organisers and participants

  • Avoid using sites with ‘Poor’ water quality classifications.
  • Develop water quality contingency plans in the event of heavy rain or poor test results.
  • Inform swimming event participants about water quality so that they can decide whether to swim.
  • For more specific information or health advice contact the Department of Health by calling the Public Health Hotline on 1800 671 738, or your local council Environmental Health Officer.

What you can do?

  • Pick up after your dog.
  • Don’t feed the ducks and geese.
  • Be aware of where and when you swim. Avoid swimming in the Derwent estuary for two days after heavy rain (>10 mm of rain over a 24 hour period) and don’t swim or allow children to play in or near stormwater outfalls (25 m on either side of outfall) or urban rivulets.

Further information

For sampling results for all sites, and further information about this program see the DEP’s latest Recreational Water Quality report.

Background to the program

Local councils, the Environmental Protection Authority and the Derwent Estuary Program collect water samples from 39 sites throughout the Derwent estuary each Tuesday from the start of December to the end of March.

All samples are analysed at the Public Health Laboratory (New Town) using the Enterolert method, which provides confirmed results within 24 hours of analysis. Results are typically reported between 24 and 48 hours after submission to the laboratory.

Sites are categorised as either Swimming Sites (Beach Watch) or Environmental Sites (Bay Watch):

  • The Swimming Sites are in locations where a significant number of people swim or conduct other primary contact recreation.
  • The Environmental Sites are not designated swimming sites, but are frequently used for secondary contact recreation, have been identified as potential sources of faecal contamination, or are sites associated with major swimming events, such as the Trans Derwent Swim.

Pathogens and health risks

Water contaminated by sewage and animal faeces may contain pathogenic micro-organisms (bacteria, viruses, protozoa) which pose a health hazard when the water is used for primary contact recreation, such as swimming. Infection may occur by swallowing, inhaling or by direct contact of contaminated water with ears, nasal passages, mucous membranes and cuts in the skin, which allow the pathogens to enter the body. The most common health conditions associated with primary contact recreation in contaminated water are gastrointestinal disorders, respiratory illnesses, eye, nose and throat infections and skin disorders.

Monitoring and guidelines

The Recreational Water Quality Guidelines for Tasmania were developed using the National Guidelines for Managing Risks in Recreational Water 2008. The Tasmanian guidelines adopt a three-tiered approach to classifying the long-term quality of a site based on available data. The tiers are:

  • Good: rolling 5-year 95th Hazen percentile value of < 200 enterococci MPN (Most Probable Number) per 100 mL.
  • Moderate (Fair): rolling 5-year 95th Hazen percentile value of 200–500 enterococci MPN per 100 mL.
  • Poor: rolling 5-year 95th Hazen percentile value of > 500 enterococci MPN per 100 mL. In this case, water at these sites is considered to be a threat to public health in the event of primary contact recreation, and the particular local council is required to advise the general public and to erect warning signs to this effect.

In addition to long-term site classification, trigger levels have been set to manage public exposure to episodic or emerging water quality issues. If a sample exceeds 140 MPN per 100 mL, the relevant authority is required to re-sample, and if two consecutive samples return a result above 280 MPN per 100 mL, the swimming site must be closed and the public notified. The beach may only be re-opened for primary contact recreation following agreement between the Director of Public Health and Council’s Authorised Officer.

For further information see the Tasmanian Recreational Water Quality Guidelines and our national Guidelines for Managing Risks in Recreational Water.