Implications for Other Tidal Estuaries
health, while the overflow is respons ible for the public health hazard and loss of
We found that the important factors to cons ider for determining ecological healrh in other tidally exchanged creeks are rhe race of the physical re-aeration of the water column, rhe hydrological in-pipe and stormwarer di luti on in co njunction with the nutrient-loading rate. A waterway 'I ndex' could be developed to co mpare hydrological characteristics and water column re-aera tion rates of Lota Creek to ocher tidally influenced creeks in Brisbane. Th is would allow extrapolation of Lora C reek findings to ocher waterway co ntamin ants and provide insight to pote n tial management options and help priori tise creeks fo r overflow abatement.
recreation amenity. Environmental concern fo r waterway pollution should sh ift from sewage to sto rmwarer for, as we have shown, srormwacer is the chief source of environmental pollu tion during wetweather overflows.
Future Direction and Conclusions T he greatest gap in our knowledge of the waterways in the study was of the exten t of hu man exposure to the public health hazard . This inform ation is essenti al for the final risk-assessment and should fo rm the bas is of a larger risk management fram ework. With chis informa tion, che knowledge gained here of rhe hydrological dilutio n of che untreated sewage ca n be used co predict the public and ecosystem health risks of ocher similar tidally influ enced coastal environments in Brisbane. Fro m ch is study we learnt ch e most-cost effective and practical way co mon itor the sewage overflow plume was to fo ll ow its movement in rime and space, while assessing the public health hazard based on WHO (2003) Microbiological Water Q uality Guidelines. Tab le 2 lists fi ve key param eters, not all are essential in future monitori ng programs. lf the community wants to increase recreational am enity in Lota Creek, future resea rch could foc us on developing methods that optimise rapid pathogen removal at th e overflow structure. (Long-term management cou ld consider methods to red uce the use of water and pipe nerworks co carry domestic waste co large wastewater treatment planes). However, while che sewer pipe networks exist, emergency sewage overflows will remai n pare of the sewerage system. T hey are an emotive issue for the public but che concern needs to be well fo unded and properly directed. Th is study has shown char stormwater should be of much greater concern fo r ecosystem
refereed paper
Acknowledgements We tha nk Dr Roger Shaw (Coastal CRC), Pier Filer and Fiona Cha ndler (B risbane City Council) for their co ntribution co rhe project. We are particularly indebted co Grant Millar (Nacu ral Resources and Mines) and Alan Geri cz (AG Enviro) fo r developing, maintai ning and monicoring rhe field instrum ents, and to Peter Pollard's poscdoccoral fellows, resea rch assistants and postgraduate students (the Tactical Response Team) Eloise Larsen, Melissa Wos, Michelle Jones, Darren Carso nT aylor, Scott Moffatt, Mark Page, Steph en Tucker, Heather Uwins and Jill Alroe who had co turn out at shore notice to sample che ephemeral events. Their generosity, dedication and enth usiasm made this scudy possible.
The Authors Dr Peter Pollard (p.pollard@griffith.edu.au} is a senior research fellow at Griffith University, program leader for Ecosystem Heal th Assessment in che Centre for Riverine Landscapes, and leader of the Coastal CRC's sewage overflow abatement project;
Ass Prof Margaret Greenway is Associate Professor in the School of Environmental Engi neering, Griffith Universiry, Nathan Q ueensland 411 1; Dr Rhys Leeming is Environmental Biochemist at CSIRO Marine Research, Castray Esplanade Hobart, T asmania 7000; Sam Bagraith is Manager Sewage Overflow Abatement Program, Brisbane Water, T C Beirne Building, Fo rtitude Valley, Brisbane Q ueensland 4006; and Prof Nicholas Ashbolt is Professor in che School of Civil and Environmental Engineering, The University of New South Wales, Sydney NSW 2052. References Anderson, P.D., D'Aco, V.J., Shanahan, P., Chapra, S.C., Buzby, M.E., C unningham, V.J., Duplessie, B.M., Hayes, E.P., Mastroccooo, F.J ., Parke, N .J ., Rader, J.C., Samuelian, J.H. and P.W. Schwab. (2004) Screening analysis of human pharmaceutical compounds in U.S. surface waters.
Environmental Science and Technology 38:838-849. ANZECC (2000) . Australian and New Zealand Guidel ines for Fresh and Marine Water Quality - Volume I, The Guidel ines. Austra lian and New Zealand Environmen t and Conservatio n Council, and Agriculture and Resource M anagement Cou ncil of Austral ia ad New Zealand. In 'National Water Quality Managemenr Strategy; No
4'. Ashbolt, N.J., C. Reidy and C.N. Haas ( I 997). Microbial health risk at Sydney' s coastal bathing beaches. In: Proc. 17th Australian \'(/atcr and Wastewater Association meeting, 16-2 1 March, 1997, Melbourne. Vol. 2. AWWA, Melbou rne, pp:104-111 .
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