2016 – Coolmunda Dam (Queensland) – E.coli
Operators at the Coolmunda Dam WTP took their regular microbacteriological sample at 0900 on 01/02/2016 at two sample locations, the picnic ground and the SunWater office on site. The sample was sent to Toowoomba Regional Water Laboratory Services, Mt Kynoch, Toowoomba for testing and analysis and arrived on 02/02/2016. SunWater received the test report from the laboratory by email at 0936 on Tuesday 09/02/2016, which showed the sample tested positive for E. coli at the picnic ground with a reading of 3 CFU/100ml and had also had unusually high detections of both total coliforms (820 CFU/100ml) and elevated total plate count (TPC) (>2,000 CFU/100ml). Records showed that the free chlorine residual at the picnic ground sample location was 0.59 mg/L on 01/02/2016 and the pH was around 7.6.
Sunwater Annual Drinking Water Quality Plan 2015/16
“Coliforms are Gram-negative, non-spore-forming, rod-shaped bacteria that are capable of aerobic and facultative anaerobic growth in the presence of bile salts or other surface active agents with similar growth-inhibiting properties. They are found in large numbers in the faeces of humans and other warm-blooded animals, but many species also occur in the environment.
Thermotolerant coliforms are a sub-group of coliforms that are able to grow at 44.5 ± 0.2°C. E. coli is the most common thermotolerant coliform present in faeces and is regarded as the most specific indicator of recent faecal contamination because generally it is not capable of growth in the environment. In contrast, some other thermotolerant coliforms (including strains of Klebsiella, Citrobacter and Enterobacter) are able to grow in the environment and their presence is not necessarily related to faecal contamination. While tests for thermotolerant coliforms can be simpler than for E. coli, E. coli is considered a superior indicator for detecting faecal contamination…” ADWG