Live Oral Presentation in person as part of National Virtual Conference AFSS Conference 2020

First steps in predicting microbial pollution in riverine recreational swimming areas in high and low flow conditions in the Australian Capital Territory (ACT), 2009-2020 (#2)

Kathryn Vincent 1 , Danswell Starrs 1 , Aparna Lal 1
  1. Australian National University, Ainslie, ACT, Australia

Research focus: Predictive water modelling; enterococci concentrations

Student level: Masters (research project)

Australian National University

Recreational swimming sites provide significant social value to users throughout Australia. Water-related gastro-intestinal illnesses are primarily due to recreational use of waterways in Australia. In the ACT, monitoring is undertaken throughout the swimming season (September – April) to test for enterococci coliforms as a bacterial indicator of faecal contamination. In line national recreational water quality guidelines, a result of >200cfu/100ml results in a closure of a swimming area to primary contact recreation.

Using publicly available data, this study examined enterococci levels at public recreational swimming sites across the Murrumbidgee River in the ACT. Statistical analysis focussed on determining if high enterococci concentrations could be predicted with streamflow and water quality.

Our study found a positive correlation between enterococci concentrations and turbidity associated with high flow conditions. The predictive accuracy of the model performed well when testing high enterococci levels during high flow conditions (57%). Prediction of high enterococci levels at low flows were less reliable (14%). As the ACT is expected to experience decreases in rainfall overall but increases in extreme rainfall events due to climate change, understanding the drivers of high enterococci at low flow conditions remains important from a public health perspective. High enterococci concentrations under low flow conditions are not well understood or explained in the literature, suggesting further research is required to explain high enterococci concentrations during low flow conditions.