2018/19: Pykes Creek Reservoir (Victoria) – E.coli

“Pykes Creek Reservoir – Detection of elevated E.coli levels) The presence of elevated E.coli levels in Pykes Creek Reservoir was detected in February and April of 2018 during routine monitoring by Western Water. After significant on-site investigation by SRW, the cause of the elevated E.coli levels was not apparent. The issue was referred to external experts and agencies during the detection period to assist in locating and addressing the source of the issue.

During the incident:

• as per SRW’s Memorandum of Understanding with Western Water, SRW continued to receive and share water quality data with Western Water over the course of the incidents • additional water quality sampling and testing was undertaken by SRW and Western Water to monitorthe situation • the storage was closed for public recreation during elevated E.coli levels, and re-opened when testing confirmed a return to safe levels • specialist testing was undertaken to better understand potential contamination sources • industry professionals/academics were engaged to provide advice on the issue • the issue was reported to all relevant agencies i.e. DHHS, and regular updates were provided to internal and external stakeholders, and • Western Water’s water treatment plant continued to successfully treat and supply drinking water to Myrniong for the duration of the event. Evidence gathered during the event indicated a strong possibility the E.coli in Pykes Creek Reservoir was a ‘natural’ bloom. SRW is convening a learning session with industry, regulators and academic experts to discuss future management of ‘natural’ E.coli blooms.

2018/19: Pykes Creek Reservoir (Victoria) – E.coli

Pykes Creek Reservoir – Detection of elevated E.coli levels (December 2018 and February 2019)

High E.coli levels in Pykes Creek Reservoir were detected between 31 December 2018 and 11 February 2019 during routine monitoring. After significant on-site investigation by Southern Rural Water (SRW) and genome sequence testing undertaken by the Australian Water Quality Centre (AWQC), the cause of the high E.coli levels was determined to be a bloom of an environmental strain of E.coli. Though unconfirmed, it is very likely that a similar event caused the high E.coli levels at Pykes Creek during the 2017–18 Financial Year.

During the incident: • as per SRW’s Memorandum of Understanding with Western Water, SRW continued to receive and share water quality data with Western Water over the course of the incidents • additional water quality sampling and testing was undertaken by SRW and Western Water to monitor the situation • the storage was closed for public recreation during high E.coli levels, and re-opened when testing confirmed a return to levels considered safe for recreational use • AWQC was engaged to undertake genome testing to identify the strain of E.coli • the issue was reported to all relevant agencies such as the DHHS, EPA & DELWP, and regular updates were provided to internal and external stakeholders, and • Western Water’s water treatment plant located at Pykes Creek continued to successfully treat and supply drinking water to the township of Myrniong for the duration of the event. Following the incident, SRW convened a workshop with industry, regulators and experts to discuss the issue of environmental E.coli, and ways to manage future incidents. SRW also participated in research undertaken by Water Research Australia that has resulted in a guidance document on managing environmental E.coli incidents from a drinking water and treatment perspective. Current research indicates that environmental E.coli strains are non-pathogenic, and they occur without fecal contamination. Regardless, environmental E.coli has been added to SRW’s risk management plans, and SRWare developing a procedure for the identification and management of environmental E.coli incidents from both a drinking and recreational water perspective.” Western Water

Escherichia coli should not be detected in any 100 mL sample of drinking water. If detected
in drinking water, immediate action should be taken including investigation of potential
sources of faecal contamination.

“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