20 August 2010
Specialised testing of the foreshore water around Fannie Bay beaches in mid-June 2010 has indicated that the E. coli responsible for elevated bacterial counts appears to have been related to faecal matter, animal or human, and was not connected with the Larrakeyah and Ludmilla outfalls.The samples, collected on 16and 18 June 2010, were analysed by a noted authority on E. coli, Associate Professor David Gordon from the Australian National University.
"The source of these E. coli was most likely faecal pollution from the catchment, which can reach the beach areas via tidal creeks and stormwater drains. The bacteria could originate from various sources, for example faecal waste from dogs, birds and feral animals, which can be washed into the waterways, particularly after rainfall events," Professor Gordon said
The Department of Health and Families (DHF) is working closely with the Department of Natural Resources, Environment, The Arts and Sport (NRETAS) and other agencies in undertaking sanitary surveys and environmental sampling to identify the sources of local contamination.
Extensive testing by NRETAS around the Larrakeyah and Ludmilla sewerage outfalls
has confirmed a very rapid die-off of E. coli bacteria in deep sea water. So it is unlikely that the outfalls were the source of the E. coli contamination in the foreshore region of affected beaches.
All Darwin beaches have been open for swimming since 20 July 2010 and DHF Environmental Health Officers are regularly monitoring beach water. In addition, weekly water samples are being taken around 200 metres offshore from Mindil and Nightcliff beaches by Surf Life Saving NT, on behalf of DHF.
These samples continue to show high water quality, with the levels of E. coli and enterococci being consistently low, with only the water close to the beaches having been affected by the land-based pollutants.
It is also believed that the presence of the blue-green algae, Lyngbya majuscula, in early June, contributed to the high E. coli counts. NRETAS officers are undertaking a separate project to identify the triggers and stimuli for the proliferation of this algae, to analyse its toxicity, and to gauge the relationship between the algae and high E. coli counts.
Anyone who has concerns with harbour or beach water quality can contact DHF Environmental Health hotline during business hours on toll free 1800 095 646.
Test results from water samples taken in the Fannie Bay foreshore area in mid-June 2010
Genotype test results - Australian National University
12 clones representing 4 fingerprints belonged to phylogroup A (15%)
24 clones representing 5 fingerprints belonged to phylogroup B1 (30%)
18 clones representing 4 fingerprints belonged to phylogroup B2 (22%)
26 clones representing 3 fingerprints belonged to phylogroup D (33%)
Media inquiries: Robin Osborne, DHF Media Director, 0488 692 781
