Review of Faecal Indicator Bacteria for Assessing Water Quality In The Yarra River

Transcription

1 Review of Faecal Indicator Bacteria for Assessing Water Quality In The Yarra River Amanda Posselt, Maree Bethel, David Kerr EPA Victoria, Ernest Jones Drive, Macleod, Victoria, 3085

2 Yarra River, Victoria, Australia

3 Yarra River, Victoria, Australia

4 Water Quality Indicators Genetic Faecal Pollution Bacteria Viruses Sterols Others E. coli Adenovirus Coprostanol Caffeine Enterococci Rotavirus Cholesterol Cryptosporidium C. Perfringens Giardia Bacterodales Nutrient Ratios

5 Recommendation to change from E. coli to enterococci in freshwater National Health and Medical Research Council Guidelines for Assessing Recreational Water Quality (NHMRC 2008) Recommended change from E. coli to enterococci in freshwater What does this mean for recreational water quality programs currently using E. coli? Do E. coli and enterococci tell the same story in freshwater? Is it appropriate to make the move from E. coli to enterococci in freshwater?

6 E. coli and enterococci Historically E. coli has been monitored in freshwater and enterococci in marine to asses recreational water quality. However, with the anticipation of a suggested move to enterococci in Upper Yarra freshwater both E. coli and enterococci were measured at 8 sites along the Yarra since April 2005 Weekly data from 5 freshwater sites, 3 estuarine sites (Melbourne Water) Conductivity Dissolved Oxygen E. coli Enterococci ph Temperature Turbidity Rainfall (daily) N Bay

7 Log 10 enterococci Yarra River Water Quality Correlations Estuarine Freshwater E. coli Ent Temp Turb Rain>5 E. coli 1 Ent Temp Turb Rain> E. coli Ent Temp Turb Rain>5 E. coli 1 Ent Temp Turb Rain> Log 10 E. coli

8 Enterococci 95 th percentiles Water Quality Classifications Do E. coli and enterococci tell the same story in terms of health risk? EPA Water Quality Ratings (E. coli) High Moderate Low < > ~80% of the time current water quality risk ratings would provide a similar risk rating to the proposed water quality risk rating Enterococci can give a more conservative approach than E. coli meaning that enterococci may give a higher risk rating than E. coli

9 E. coli to remain the indicator of choice for recreational water quality in rivers Generally E. coli and enterococci do tell the same story in the Yarra however, using enterococci will sometimes give a more conservative recreational water quality risk rating This is the case for both freshwater and estuarine In the absence of epidemiological data for enterococci in freshwater, and in the interest of keeping historical data consistent with future data, EPA Victoria will continue to use E. coli to measure recreational water quality

10 The bigger picture: Issues with enterococci Faecal drain program Melbourne Water Retail Water Companies Catchment Management Authority Sustainability Victoria Yarra River Action Plan Parks Victoria DHS EPA YRIRP Pathogens in commercial sources Local Government DSE

11 Melbourne Water: Faecal source tracking Human Sewage Ageing infrastructure Illegal cross connections Septics Non-human faecal Animals Non-human/ Non-faecal Commercial (Food) Council depots

12 Pathogens in food related storm water pollution 12% of samples: E. coli org/100ml 25% samples: E. coli & enterococci org/100ml 63% samples: enterococci org/100ml Campylobacter, Listeria and/or Salmonella detected in about half of all samples No Giardia or Cryptosporidium No human viruses (Enteroviruses, Adenoviruses, Reoviruses; Hepatitis A, Rotavirus, Norovirus I and II)

13 Summary There are significant concentrations of enterococci associated with non-human/non faecal sources which probably present a lower health risk than those from faecal sources This confounds the use of enterococci as an indicator of recreational water quality and further supports the decision to continue to use E. coli as the recreational water quality in rivers

14 Recommendations Faecal indicator bacteria (such as E. coli and enterococci) used in isolation as recreational water quality indicators is outdated. Whilst EPA is continuing to use E. coli, it is investigating (with external stakeholders) emerging methods that can be used in conjunction with E. coli water quality data to assess recreational water quality. Integrated water quality assessments which include sanitary surveys Genetic source tracking (Bacteroidales), Ecowise Environmental

15 Acknowledgements Melbourne Water City of Yarra