Numurkah (Victoria) – Blue Green Algae (Aphanizomenonaceae family)

In accordance with the Victorian Blue-Green Algae Circular, GVW notified DoH in February 2023
of a significant increase in BGA in the raw water at the Numurkah WTP. Toxin analysis, including
qPCR toxin gene copies, was undertaken to classify the toxicity of the bloom due to the
Laboratory identification of the dominate species in the Aphanizomenonaceae family, a
potentially toxic group. All samples were negative for cyanobacterial toxins and toxin genes,
specifically Cylindrospermopsin and Deoxy-cylindrospermopsin. Results were consistent with
blooms in recent years that had been misidentified as C. ovalisporum. It is possible that like the
previous blooms, the environmentally plastic species Dolichospermum brachiatum dominated
the bloom, but lacked the diacritical features to classify to species resulting in the microbiologists  only reporting to the family group.

Numurkah (Victoria) – Trichloroacetic Acid

2010/11: Numurkah 0.140mg/L Trichloroacetic Acid

Australian Guidelines Trichloroacetic Acid 0.100mg/L

“Chloroacetic acids are produced in drinking water as by-products of the reaction between chlorine and naturally occurring humic and fulvic acids. Concentrations reported overseas range up to 0.16mg/L and are typically about half the chloroform concentration. The chloroacetic acids are used commercially as reagents or intermediates in the preparation of a wide variety of chemicals. Monochloroacetic acid can be used as a pre-emergent herbicide, dichloroacetic acid as an ingredient in some pharmaceutical products, and trichloroacetic acid as a herbicide, soil sterilant and antiseptic.” Australian Drinking Water Guidelines – National Health and Medical Research Council…

There are no epidemiological studies of TCA carcinogenicity in humans. Most of the human health data for chlorinated acetic acids concern components of complex mixtures of water disinfectant by-products. These complex mixtures of disinfectant by-products have been associated with increased potential for bladder, rectal, and colon cancer in humans [reviewed by Boorman et al. (1999); Mills et al. (1998)].” Ref: tmp/Trichloroacetic acid (TCA) CASRN 76-03-9 IRIS US EPA.htm

Numukah (Victoria) – Chloral Hydrate

Numurkah 0.043mg/L Goulburn Valley Water Chloral Hydrate 2011/12

Numurkah 0.051mg/L Goulburn Valley Water Chloral Hydrate 2010/11

2004 Australian Drinking Water Guideline: Trichloroacetaldehyde (chloral hydrate): 0.02mg/L

2011 Australian Drinking Water Guideline: Trichloroacetaldehyde (chloral hydrate): 0.1mg/L

“Chloral hydrate is a disinfection by-product, arising from chlorination of water containing naturally occurring organic material (NOM). Chloral hydrate has only been detected by Goulburn Valley Water since changing to a new contract testing laboratory in November 2007. The Department of Health is currently conducting a study into the detection of chloral hydrate across Victoria.”