2016 December – Wulguru (Queensland) – E.coli

Blue Ridge Avenue, Wulguru (Queensland): E.coli
Incident Description: On 28th December 2016 18 org/100ml E.coli was detected at treated water sample point Blue Ridge Avenue which is the sample point for Yongala Reservoir. Further samples came back clear. This resulted in a rolling percentage of 99.9%.
Corrective and Preventative Actions: Hand-dosing at Yongala Reservoir was increased from twice weekly to every second day to maintain a chlorine residual. A temporary chlorinator at Yongala reservoir was later installed to remove the need for hand-dosing. The system continues to be monitored closely.

“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 2011