green tree frogs gaining access to the inside of the service reservoir. A range of
preventative actions were already implemented to reduce this risk of recurrence in all
reservoirs review of rechlorination, vermin-proofing of reservoirs and regular
preventative maintenance checks.
“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
2014/15 – Glemore Water Treatment Plant – Cyanobacteria bloom and cylindrospermopsin detected (Source water)
“Cylindrospermopsin is believed to have been the causative agent in the Palm Island “mystery disease” poisoning incident in Queensland in 1979, in which 148 people were hospitalised (Byth 1980). It was subsequently shown that water from Solomon Dam on Palm Island contained blooms of toxic C. raciborskii (Hawkins et al 1985). C. raciborskii has been found in many water supply reservoirs in northern, central and southern Queensland. Although C. raciborskii
and A. ovalisporum are both considered to be predominantly tropical/sub-tropical in terms of habitat, with most Australian blooms occurring in Queensland, C. raciborskii also occurs in the Murray-Darling River system (Baker and Humpage 1994). In recent years there has been increasing evidence of detection in the River Murray and C. raciborskii was detected in the major blooms that affected several hundred kilometres of the River Murray on the border between New South Wales and Victoria in 2009 and 2010 (NSW Office of Water 2009, MDBA 2010). C. raciborskii is not a scum-forming organism, but forms dense bands below the water surface in stratified lakes, while A. ovalisporum may form thick brown surface scums (Shaw et al 1999). Although no reports of human poisoning attributable to cylindrospermopsin have appeared since the Palm Island incident, recent cattle deaths in Queensland are attributed to
this toxin (Saker et al 1999)”. (Fact Sheet Cylindrospermopsin ADWG 2011).
2014/15 – Glenmore Water Treatment Plant – Trihalomethanes – Rockhampton
THM concentrations exceeding the health guideline value of 250 µg/L were measured in two (2) reticulation sample points and a supply reservoir on 19 March 2015. All follow-up samples from these sites had THM levels less than 250 µg/L however, slight exceedances were detected on 3 other reticulation sample sites on 31 March and 8 April. These elevated levels of THMs were due to chlorine predosing at the GWTP which was undertaken to treat high levels of manganese and associated organic carbon following the Tropical Cyclone Marcia event.
Trihalomethanes Australian Guideline Level 250μg/L (0.25mg/L)
Why and how are THMs formed?
“When chlorine is added to water with organic material, such as algae, river weeds, and decaying leaves, THMs are formed. Residual chlorine molecules react with this harmless organic material to form a group of chlorinated chemical compounds, THMs. They are tasteless and odourless, but harmful and potentially toxic. The quantity of by-products formed is determined by several factors, such as the amount and type of organic material present in water, temperature, pH, chlorine dosage, contact time available for chlorine, and bromide concentration in the water. The organic matter in water mainly consists of a) humic substance, which is the organic portion of soil that remains after prolonged microbial decomposition formed by the decay of leaves, wood, and other vegetable matter; and b) fulvic acid, which is a water soluble substance of low molecular weight that is derived from humus”. US EPA
2014/15 – Glenmore Water Treatment Plant – Manganese – Rockhampton
A Manganese concentration of 0.8 mg/L was measured in the drinking water from the Glenmore Water Treatment Plant (GWTP) on 11 March 2015. A follow-up sample collected from the GWTP on the same day also exceeded the health guideline value of 0.5 mg/L. Fifteen (15) of the more than 250 samples collected from Rockhampton water supply scheme from 12 to 31 March were also non-compliant for manganese. The exceedances for manganese was due to the very low dissolved oxygen levels (<2 mg/L), high organic carbon load, and greater amounts of dissolved, organically complexed manganese ions in the source water flushed out from Alligator Creek following the Tropical Cyclone Marcia event.
Manganese: ADWG Guidelines 0.5mg/L. ADWG Aesthetic Guideline 0.1mg/L
Manganese is found in the natural environment. Manganese in drinking water above 0.1mg/L can give water an unpleasant taste and stain plumbing fixtures