Improving Water Quality

We have focussed on the recreational water quality of Blackmans Bay Beach (south) over the past year, following some poor results and a rating of ‘poor’ from the Derwent Estuary Program. The southern end is defined by where the large stormwater outfall extends into the water.

Our officers have carried out intensive investigation into the issues at the southern end of the beach. We have worked with TasWater to identify issues, carry out repairs and develop solutions, such as the low-flow diversion from stormwater to sewer, to improve the water quality.

The investigations and actions from the past year include:

  • Weekly beach and stormwater sampling program from November 2018 (included beach and stormwater outfalls).
  • TasWater and the Derwent Estuary Program also conducted marine based sampling during this period.
  • Source tracking of contamination.
  • Identification and rectification of a number of illegal domestic cross-connections.
  • The formation of a Joint Investigative Team between Council and TasWater.
  • Collaboration with TasWater to identify damaged sewer infrastructure within the catchment area.
  • A short-term trial diversion system at the Illawarra Road outfall (note: this was unsuccessful beyond a few weeks).
  • Working with TasWater for approval to divert low-flows of stormwater to sewer.
  • Installation of Illawarra Road and current installation of Blackmans Bay mid outfall low-flow diversions of stormwater to sewer.
  • Monitoring the number and location of seagulls at the beach.
  • Sand sediment sampling.
  • Engagement of a consultant with a specialist background in water quality issues and particularly the Derwent Estuary.
  • Active participation in a Source Tracking Working Group with the Department of Health, TasWater, EPA, Derwent Estuary Program, City of Hobart and the Clarence City Council.
  • Appointment of a permanent full-time Stormwater Investigation Officer to focus on stormwater impacts on recreational water quality.

Below are some frequently asked questions about the investigations. If you would like further information, contact our Environmental Health Officers on 6211 8200.


Is the southern end of Blackmans Bay Beach closed?

Council does not have the ability to close or prevent access to a beach.

The long-term rating at Blackmans Bay Beach south has been reset and is now lifted by the Department of Health. The advisory signs recommending not to swim have been removed.

We do remind people that swimming is not recommended several days following heavy rain.



What is Council doing now?

Council has recently installed a low-flow diversion at the Illawarra stormwater outfall.  This will divert the low-flows of stormwater to the TasWater sewer network.

This means the system should catch any contaminants that are coming through the stormwater system.

The low-flow is not designed to divert any rainfall. The advice to not swim after heavy rainfall remains in place, due to the increase in water flowing over the land and through the system before entering the marine environment.

Council will continue to sample the stormwater outfalls and investigate issues further up the catchment.

The Environment Protection Authority is also currently conducting nutrient and sterol analysis in the Kingston Beach and Blackmans Bay catchment areas over the duration of the summer swimming season.

Were the seagulls a factor in the poor water quality?

Initially the arrival of the seagulls coincided with poor water quality. However, recent periods of good water quality results have been observed with very large numbers of seagulls present on the beach, indicating that the seagulls are not likely to have been the primary cause of the poor water quality results.

What is the process for reviewing the beach grading?

Requesting a review of the beach grading, outside of the normal five year average grading process, requires a collaborative approach with the Director of Public Health and the Department of Health.  Council needs to demonstrate that substantial steps have been taken to remediate the problem, as well as demonstrating that the water consistently complies with the Recreational Water Quality Guidelines.

We are happy to announce as from Tuesday, 25 August, the Department of Health has reviewed Council’s actions and has lifted the advisory against swimming and resent the rating.

Council’s investigations have led to various cross connections and sewer leakage issues being rectified in the catchment area. The installation of the low flow diversions are also a significant investment in protecting beach water quality and amenity.